In my last post, I pointed out the statutory requirement, contained in Article B4(1) of Schedule 1 of The Building Regulations 2010, that:
The external walls of the building shall adequately resist the spread of fire over the walls…
I then began to examine the guidance given by the government in Approved Document, Volume 2, at the corresponding part B4, as to how this statutory requirement can be met. Two alternative routes to compliance are given in Section 12.5:
In my last post also, I examined the provisions of paragraphs 12.6 to 12.9 and in particular of 12.6 and 12.7 which concern the fire properties of the materials used in construction. I explained that, for buildings over 18m high:
a) The requirement of 12.6 can be satisfied if the materials are UK Class 0. This classification can be achieved through satisfactory performance in two UK fire tests, BS 476 part 7 ‘Surface Spread of Flame’; and part 6 ‘Fire Propagation’. In both of these it is the surface of the board or panel that is subjected to assault by fire.
b) The requirements of 12.7 appear to apply to insulation products only. The materials must either survive trial by a furnace at 750° C, or have a calorific value of less than 3 MJ/kg. I argue that no material with a substantial component of a polymer like the PIR of the Celotex boards, or the PE of the Reynobond panels, could possibly pass these tests.
In this post I describe the BS 8414 fire test, which is offered as an alternative route to compliance at paragraph 12.5. In following posts I plan to:
Continue reading Grenfell Tower: was the cladding legal or not? (part 2)
