In my last post, I took issue with the Government’s claim that the building regulations require all elements of the cladding system of high buildings to be of limited combustibility. Table A7 of Approved Document B2 indicates clearly that it is insulation material that is covered by the requirement of paragraph 12.7. Also, if ‘all elements’ were meant, then would it not have been said, in simple terms?
Further confirmation that the Government position is insupportable comes from the two leading commentaries on the building regulations. Both seem to take it for granted that AD B2 12.7 applies to insulation products and material only, as I outline later in this post.
First, however, I examine the origins of the Government’s position. Some time this year, the Centre for Window Cladding and Technology (CWCT) published Technical Note 98 on the ‘Fire Performance of Facades – Guide to the requirements of UK Building Regulations’. They comment that while 12.7 ‘specifically’ refers to ‘insulation materials and filler materials’, the paragraph:
is now being interpreted more generally
For this more general interpretation, the CWCT make reference to the BCA’s (Building Control Alliance’s) Technical Guidance Note (TGN) 18 on the ‘Use of Combustible Cladding Materials on Residential Buildings’, whose first edition was published in June 2014. It has three remarkable features:
- It recommends that under the individual components’ route to compliance, ‘all elements of the cladding system’ should be of limited combustibility (as defined in Table A7 of AD B2).
- It claims that this is also what the Approved Document recommends.
- For the alternative whole system route to compliance, it purports to introduce Desktop Studies in lieu of actual fire tests. It also gives the impression that the Approved Document allows for ‘assessments’ rather than actual tests.
I take each of these in turn.
Continue reading Grenfell Tower: the road to ambiguity (part 1)
