Items where Subject is "B4: External fire spread"
 | Up a level |
- Library of Congress Subject Areas (55)
- K Law (55)
- The Building Regulations 2010 (55)
- B4: External fire spread (55)
- The Building Regulations 2010 (55)
- K Law (55)
a1 loading
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
absorptive material
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
air permeability
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
approved document
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
Guidance on the design and construction of fire mains is given in BS 9990.
audit documentation
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
b2 internal fire spread linings
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
b3 internal fire spread structure
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
Guidance on the design and construction of fire mains is given in BS 9990.
b4 external fire spread
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
b5 access and facilities for the fire service
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
background ventilator
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
boundary
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
building and land associated with the building
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
building control body
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
building regulations
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
can be ignored when assessing separation distance. This does not apply where the canopy is enclosed by side walls. Distance to relevant boundary measured from building line See para 11.12
NOTE: Projections from the building line, such as a canopy or a loading platform, can be ignored when assessing separation distance. This does not apply where the canopy is enclosed by side walls.
Distance to relevant boundary measured from building line
See para 11.12
cavity
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
cavity barrier
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
cavity stop
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
cavity width
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
chimney
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
circulation space
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
combustion appliances and fuel storage systems 2010 edition incorporating 2010 and 2013 amendments
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
commissioning
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
common balcony
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
communal or common (area facilities or entrances)
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
compartment (fire)
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
compartment wall
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
compartment wall or floor
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
compartmentation
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
construction phase
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
construction site
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
contrast visually
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
cquivalent area
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
d2 or better
NOTES:
Separation distances do not apply to the boundary between roofs of a pair of semi-detached dwellinghouses and to enclosed/covered walkways. However, see Diagram 5.2 if the roof passes over the top of a compartment wall.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test may be regarded as having a BROOF(t4) designation.
1. The designation of external roof surfaces is explained in Appendix B.
2. Not acceptable on any of the following buildings.
a. Dwellinghouses in terraces of three or more dwellinghouses.
b. Any other buildings with a cubic capacity of more than 1500m3.
3. Acceptable on buildings not listed in (1) if both of the following apply.
a. Part of the roof has a maximum area of 3m2 and is a minimum of 1500mm from any similar part.
b. The roof between the parts is covered with a material rated class A2-s3, d2 or better.
d2 rating by test may be regarded as having a BROOF(t4) designation. 1. The designation of external roof surfaces is explained in Appendix B. 2. Not acceptable on any of the following buildings. a. Dwellinghouses in terraces of three or more dwellinghouses. b. Any other buildings with a cubic capacity of more than 1500m3. 3. Acceptable on buildings not listed in (1) if both of the following apply. a. Part of the roof has a maximum area of 3m2 and is a minimum of 1500mm from any similar part. b. The roof between the parts is covered with a material rated class A2-s3
NOTES:
Separation distances do not apply to the boundary between roofs of a pair of semi-detached dwellinghouses and to enclosed/covered walkways. However, see Diagram 5.2 if the roof passes over the top of a compartment wall.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test may be regarded as having a BROOF(t4) designation.
1. The designation of external roof surfaces is explained in Appendix B.
2. Not acceptable on any of the following buildings.
a. Dwellinghouses in terraces of three or more dwellinghouses.
b. Any other buildings with a cubic capacity of more than 1500m3.
3. Acceptable on buildings not listed in (1) if both of the following apply.
a. Part of the roof has a maximum area of 3m2 and is a minimum of 1500mm from any similar part.
b. The roof between the parts is covered with a material rated class A2-s3, d2 or better.
definitions (ada)
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
design air permeability
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
design and build
Guidance on the design and construction of fire mains is given in BS 9990.
direct distance
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
direct transmission
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
draught diverter
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
dwelling
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
dwelling (l2a)
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
dwelling type
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
dwellinghouse
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
early warning system
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
element of structure
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
equivalent area
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
exempt buildings and work
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
exit passageway
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
explanation of terms used
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
external wall
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
final certificate
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
fire compartment
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
fire resistance
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
Guidance on the design and construction of fire mains is given in BS 9990.
fire resisting (Fire resistance)
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
Guidance on the design and construction of fire mains is given in BS 9990.
fire risk assessment
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
Guidance on the design and construction of fire mains is given in BS 9990.
fire safety - volume 1: dwellings. 2019 edition - for use in england
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
Guidance on the design and construction of fire mains is given in BS 9990.
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
fire safety - volume 2: buildings other than dwellings. 2019 edition - for use in england
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.
a. The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.
b. The intensity of a fire is related to the building use, but can be moderated by a sprinkler system.
c. Fires in ‘residential’ and ‘assembly and recreation’ buildings (purpose groups 1, 2 and 5) represent a greater risk to life.
d. A building on the far side of the relevant boundary meets both of the following conditions.
i. Has a similar elevation to the one in question.
ii. Is the same distance as the one in question from the common boundary.
e. The radiated heat passing through any part of the fire resisting external wall may be discounted.
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
fire-separating element
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
fire-stop (Fire-stopping)
Guidance on the design and construction of fire mains is given in BS 9990.
firefighting lift
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
firefighting lobby
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
firefighting shaft
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
firefighting stair
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
fit-out work
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
flanking element
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
floating floor
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
floating layer
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
floor
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
fluepipe
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
following edge (of door)
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
free area
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
frequency band
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
going
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
guarding
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
health and safety file
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
heat input rate
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
height
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
internal wall
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
isolation
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
local authority building control
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
material alteration
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
material changes of use
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
materials
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
means of escape
In low rise buildings without deep basements, access for firefighting personnel is typically achieved by providing measures for fire service vehicle access in Section 13 and means of escape.
non-combustible material
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
non-worsening (of compliance)
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: Projections from the building line
NOTE: Projections from the building line, such as a canopy or a loading platform, can be ignored when assessing separation distance. This does not apply where the canopy is enclosed by side walls.
Distance to relevant boundary measured from building line
See para 11.12
NOTES: Separation distances do not apply to the boundary between roofs of a pair of semi-detached dwellinghouses and to enclosed/covered walkways. However
NOTES:
Separation distances do not apply to the boundary between roofs of a pair of semi-detached dwellinghouses and to enclosed/covered walkways. However, see Diagram 5.2 if the roof passes over the top of a compartment wall.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test may be regarded as having a BROOF(t4) designation.
1. The designation of external roof surfaces is explained in Appendix B.
2. Not acceptable on any of the following buildings.
a. Dwellinghouses in terraces of three or more dwellinghouses.
b. Any other buildings with a cubic capacity of more than 1500m3.
3. Acceptable on buildings not listed in (1) if both of the following apply.
a. Part of the roof has a maximum area of 3m2 and is a minimum of 1500mm from any similar part.
b. The roof between the parts is covered with a material rated class A2-s3, d2 or better.
notified body
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
notional boundary
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
octave band
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
one-third octave band
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
outcomes-based system
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
part b - fire safety
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
Guidance on the design and construction of fire mains is given in BS 9990.
passive stack ventilation (psv)
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
plans certificates
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
primary thermal store
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
principal contractor
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
principal designer
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
principal works
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
private (area facilities or entrances)
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
project performance
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
protected entrance hall/landing
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
proven
Guidance on the design and construction of fire mains is given in BS 9990.
purpose group
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
rated heat input
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
reasonably practicable
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
regulation
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
regulation 7 - materials and workmanship
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
relevant boundary
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
resilient layer
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
risk assessment
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
risk assessments
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
roof
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
rooflight
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
room
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
room for residential purposes
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
room-sealed appliance
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
safety case
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
sanitation hot water safety and water efficiency 2015 edition with 2016 amendments
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
section
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
Cavity barriers should be provided in accordance with Section 5 in dwellinghouses and Section 8 in flats.
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
see Diagram 5.2 if the roof passes over the top of a compartment wall. Polycarbonate and uPVC rooflights that achieve a class C-s3
NOTES:
Separation distances do not apply to the boundary between roofs of a pair of semi-detached dwellinghouses and to enclosed/covered walkways. However, see Diagram 5.2 if the roof passes over the top of a compartment wall.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test may be regarded as having a BROOF(t4) designation.
1. The designation of external roof surfaces is explained in Appendix B.
2. Not acceptable on any of the following buildings.
a. Dwellinghouses in terraces of three or more dwellinghouses.
b. Any other buildings with a cubic capacity of more than 1500m3.
3. Acceptable on buildings not listed in (1) if both of the following apply.
a. Part of the roof has a maximum area of 3m2 and is a minimum of 1500mm from any similar part.
b. The roof between the parts is covered with a material rated class A2-s3, d2 or better.
separated part
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
Provisions for the fire properties of roofs are given in other parts of this document.
a. Requirement B1 – for roofs that are part of a means of escape.
b. Requirement B2 – for the internal surfaces of rooflights as part of internal linings.
c. Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.
d. Section 11 – the circumstances in which a roof is subject to the provisions for space separation.
separating floor
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
separating wall
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
should
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
significant risks
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
site
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
NOTES:
The notional boundary should be set in the area between the two buildings using the following rules:
1. The notional boundary is assumed to exist in the space between the buildings and is positioned so that one of the buildings would comply with the provisions for space separation having regard to the amount of its unprotected area. In practice, if one of the buildings is existing, the position of the boundary will be set by the space separation factors for that building.
2. The siting of the new building, or the second building if both are new, can then be checked to see that it also complies, using the notional boundary as the relevant boundary for the second building.
Notional boundary
Site boundary
Compliance with the provisions for space separation in respect of building A
Compliance with the provisions for space separation in respect of building B
See para 11.5
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
The boundary that a wall faces is the relevant boundary (Diagram 11.2). It may be one of the following.
a. The site boundary.
b. The centre line of a space where further development is unlikely, such as a road, railway, canal or river.
c. An assumed notional boundary between two buildings on the same site (Diagram 11.3) where either of the following conditions is met.
i. One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1 or 5).
ii. The buildings will be operated/managed by different organisations.
spacing
Space separation may be disregarded if a canopy is all of the following.
a. Free-standing.
b. Above a limited risk or controlled hazard.
c. A minimum of 1000mm from the relevant boundary.
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
specified attachment
The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of vertical fire spread as well as the risk of ignition from flames coming from adjacent buildings.
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
storey
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
storey exit
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
such as a canopy or a loading platform
NOTE: Projections from the building line, such as a canopy or a loading platform, can be ignored when assessing separation distance. This does not apply where the canopy is enclosed by side walls.
Distance to relevant boundary measured from building line
See para 11.12
suitable
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
supported wall
Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government.
tapered tread
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
the management regulations
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
thermal element
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.
thermoplastic material
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
Table 12.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 12.1) classification. The method of classifying thermoplastic materials is given in Appendix B.
total useful floor area
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
toxic substances 1992 edition incorporating 2002 2010 and 2013 amendments
The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.
travel distance
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 11.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 11.4). Table 12.1 sets out separation distances by the type of roof covering and the size and use of the building.
In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/ EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.
unprotected area
External fire spread
B4.(1)The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.
(2)The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.
Regulation 7 – Materials and workmanship
(1)Building work shall be carried out—
(a)with adequate and proper materials which—
(i)are appropriate for the circumstances in which they are used,
(ii)are adequately mixed or prepared, and
(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and
(b)in a workmanlike manner.
(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.
(3)Paragraph (2) does not apply to—
(a)cavity trays when used between two leaves of masonry;
(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6))if that part is connected to an external wall;
(c)door frames and doors;
(d)electrical installations;
(e)insulation and water proofing materials used below ground level;
(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
(g)membranes;
(h)seals, gaskets, fixings, sealants and backer rods;
(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
(j)window frames and glass.
(4)In this regulation—
(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—
(i)contains one or more dwellings;
(ii)contains an institution; or
(iii)contains a room for residential purposes(excluding any room in a hostel, hotel or boarding house); and
(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.
The external envelope of a building should not contribute to undue fire spread from one part of a
building to another part. This intention can be met by constructing external walls so that both of
the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building and spread of
fire over the outside surface is restricted.
b. The materials used to construct external walls, and attachments to them, and how they are
assembled do not contribute to the rate of fire spread up the outside of the building.
The extent to which this is necessary depends on the height and use of the building.
The external envelope of a building should not provide a medium for undue fire spread to
adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by
constructing external walls so that all of the following are satisfied.
a. The risk of ignition by an external source to the outside surface of the building is restricted.
b. The amount of thermal radiation that falls on a neighbouring building from window openings
and other unprotected areas in the building on fire is not enough to start a fire in the other
building.
c. Flame spread over the roof and/or fire penetration from external sources through the roof is
restricted.
The extent to which this is necessary depends on the use of the building and its position in relation
to adjacent buildings and therefore the site boundary.
Table 10.1 Reaction to fire performance of external surface of walls
‘Relevant buildings’ as defined in regulation 7(4) (see paragraph 10.10)
NOTES:
In addition to the requirements within this table, buildings with a top occupied storey above 18m should also meet the provisions of paragraph 10.6.
In all cases, the advice in paragraph 10.4 should be followed.
1. The restrictions for these buildings apply to all the materials used in the external wall and specified attachments (see paragraphs 10.9 to 10.12 for further guidance).
2. Profiled or flat steel sheet at least 0.5 mm thick with an organic coating of no more than 0.2mm thickness is also acceptable.
3. Timber cladding at least 9mm thick is also acceptable.
4. 10m is measured from the top surface of the roof.
Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes (excluding any room in a hostel, hotel or a boarding house). It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
NOTE: The above includes student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. See regulation 7(4) for the definition of relevant buildings.
NOTE: The requirement in regulation 7(2) is limited to materials achieving class A2-s1, d0 or class A1.
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.
Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).
Particular attention is drawn to the following points.
a. Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.
b. Internal linings should comply with the guidance provided in Section 4.
c. Any part of a roof should achieve the minimum performance as detailed in Section 12.
d. As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).
e. Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).
f. Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 10.15g.
g. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.
This section does not deal with fire resistance for external walls. An external wall may need fire resistance to meet the requirements of Section 3 (Means of escape – flats), Section 6 (Loadbearing elements of structures – flats) or Section 11 (Resisting fire spread from one building to another).
The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.
a. Follow the provisions given in paragraphs 10.5 to 10.8, which provide guidance on all of the following.
i. External surfaces.
ii. Materials and products.
iii. Cavities and cavity barriers.
b. Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.
In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall, to reduce the risk of fire spread over the wall.
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
NOTES:
Intermediate values may be obtained by interpolation.
1.The total percentage of unprotected area is found by dividing the total unprotected area by the area of a rectangle that encloses all the unprotected areas, and multiplying the result by 100.
Exclude external walls of protected stairways when assessing unprotected areas (see Diagram 3.10).
In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 11.5.
Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 11.6).
a. The canopy is attached to the side of a building.
b. The edges of the canopy are a minimum of 2m from the relevant boundary.
Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.
This boundary coincides with and is therefore relevant to side A
The boundary is parallel to side B2
But the relevant boundary may be the centre line of a road, railway, canal or river
NOTES:
This boundary is at less than 80 degrees to side C and is therefore relevant to side C
This diagram sets out the rules that apply in respect of a boundary for it to be considered as a relevant boundary.
For a boundary to be relevant it should comply with one of the following:
a. Coincide with the side of the building (A).
b. Be parallel to the side of the building (B1 or B2).
c. Be at an angle of maximum 80 degrees to the side of the building (C).
This boundary is parallel to and therefore relevant to side B1
See para 11.5
Area of fire resisting wall with materials more than 1mm thick and with a reaction to fire performance worse than class B-s3, d2 = a x b
Area of wall counted as unprotected area = 0.5a x b
Area of fire resisting wall with materials having a reaction to fire performance better than class B-s3, d2
See para 11.7
The unprotected area of the external wall of a stairway forming a protected shaft may be disregarded for separation distance purposes
Roofs pitched at an angle of less than 70 degrees may be disregarded for separation distance purposes
Represents an unprotected area of not more than 1m2 which may consist of two or more smaller areas within an area of 1000mm X 1000mm
Represents an area of not more than 0.1m2
See para 11.11
Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B4, are called unprotected areas.
Where a fire resisting external wall has a surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 11.4).
Minimum distance (a) between side of building and relevant boundary (m) Maximum total area of unprotected areas (m2)
See para 11.18
Unprotected areas should meet the conditions in Diagram 11.5, and the rest of the wall should be fire resisting from both sides.
External surface materials facing the boundary should be class B-s3, d2 or better.
Unprotected areas should not exceed the result given by one of the methods in paragraph 11.16, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in section 4.
2. No limit in the case of any space described in 2a, b and c.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of diagram 12.1.
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
If the performance of thatch or wood shingles cannot be established, they should be regarded as having an EROOF(t4) classification in Table 12.1.
NOTE: Consideration can be given to thatched roofs being closer to the relevant boundary than shown in Table 12.1 if, for example, all of the following precautions (based on the LABC publication Thatched Buildings (the Dorset Model): New Properties and Extensions) are incorporated in the design.
a. The rafters are overdrawn with construction having not less than 30 minutes’ fire resistance.
b. The guidance given in Approved Document J is followed.
c. The smoke alarm installation (see Section 1) extends to the roof spaces.
usable
Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.
NOTE: Guidance on regulation 7(1) can be found in Approved Document 7.
utility stair
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
Other than for the purposes of Diagram 5.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a BROOF(t4) classification.
wall
External walls and specified attachments are defined in regulation 2 and these definitions include any parts of the external wall as well as balconies, solar panels and sun shading.
The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 10.1. The provisions in Table 10.1 apply to each wall individually in relation to its proximity to the relevant boundary.
Wall sufficiently distant from relevant boundary to be a 100% unprotected area
Wall on or very close to the relevant boundary: very limited amounts of unprotected area
Wall not on, or not very close to, but not sufficiently far from relevant boundary that it can be a wholly unprotected area
Amount of unprotected area dependent on distance from relevant boundary
See para 11.4
wholesome water
Where regulation 7(2) applies, that regulation prevails over the provisions within this section.
window
NOTES:
1.There are restrictions on the use of plastic rooflights in the guidance to requirement B2 in Section 4.
2.Surrounding roof covering to be a material of class A2-s3, d3 or better for at least 3m distance.
3.Where Diagram 5.2a or 5.2b applies, rooflights should be at least 1500mm from the compartment wall.
See paras 12.5 and 12.6
NOTES:
None of the above designations are suitable for protected stairways.
Polycarbonate and uPVC rooflights that achieve a class C-s3, d2 rating by test (see paragraph 12.7) may be regarded as having a BROOF(t4) classification.
Where Diagram 5.2a or 5.2b applies, rooflights should be a minimum of 1500mm from the compartment wall.
If double-skinned or laminate products have upper and lower surfaces of different materials, the greater distance applies.
1. See also the guidance to requirement B2 in Section 4.
2. The designation of external roof surfaces is explained in Appendix B.
3. Single-skinned rooflight only, in the case of non-thermoplastic material.
4. The rooflight should also meet the provisions of Diagram 12.1.
The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.
Table 12.2 and Diagram 12.1 set the limitations for using plastic rooflights whose lower surface has a minimum class D-s3, d2 rating.
When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a BROOF(t4) classification.
