By amending Regulation 7 of the Building Regulations 2010 under The Building (Amendment) Regulations 2018, and the Approved Document B, combustible materials are now banned on the elevations of relevant high rise buildings so that materials which become part of an external wall of a high-rise building (ie a building over 18,m) now have to be of European Classification A2-d1, d0 (i.e. of limited combustibility) or Class A1 (non-combustible)
However under the Building (Amendment) Regulations 2018, Regulation 7(3), certain materials are exempt such as intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B Schedule 1
Regulation 7 (4) (a) states:
(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.”
How do you measure if the building is 18m high?
Regulation 7 (4) (b) states:
(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.”
Although ‘combustible;’ materials may be permitted on relevant buildings under 18 m designers must still comply with from Part B of Schedule 1 to the Building Regulations 2010. Guidance on regulation 7(1) can be found in Approved Document 7.
Part B of Schedule 1 to the Building Regulations 2010 states.
“B4 (1) The external walls of the building shall adequate 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”.
The Intention of this Regulation stated under Approved Document B Volume 1, 2019 edition:
“Resisting fire spread over external walls
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.”