Building Regulations, Part B:2006 (Volumes 1 & 2) make provisions which limit the use, near a boundary, of roof coverings which will not give adequate protection against the spread of fire over them. (The term ‘Roof coverings’ refers to the external layers of the roof but not the roof construction as a whole). The provisions regarding roof coverings are principally concerned with the performance of roofs when exposed to fire from the outside.
The performance of roof coverings is designated by reference to the test methods specified in BS476-Part 3:2004, or in accordance with BS EN 13501-5:2005.
Under BS476, the external coverings of roofs are classified by two letters in the range A-D, with an AA rating being the best. The first letter indicates the time for a standard flame to penetrate to a certain depth in the roof covering, while the second letter is a measure of the spread of flame over a roof surface.
These two-letter ratings are used by the Building Regulations to define minimum separation distances for roofs from adjacent property boundaries, and roof coverings designated as AA, AB or AC are un-restricted in respect this regulation.
The table below (reproduced from Approved Document B) sets out building/boundary separation distances for various categories of fire performance.
IKO’s bituminous membrane systems are tested and certified by Exova Warringtonfire. As a result, the following membranes gained an AA Fire Rating in accordance with the Building Regulations. They are also approved by the LPCB:
- IKO Ultra Prevent
- IKO Mach One
- IKO Safestick
- IKO Superflex
- IKO Goldseal
- IKO ProTorch
For further information, please refer to Approved Document B (2006 Edition): Fire Safety (Volumes 1 &2).