The Government testing program
The Grenfell Tower calamity highlighted the possible danger of employing combustible cladding on high rise buildings. Of the two main cladding components, the aluminium polyethylene (PE) composite rainscreen outer cladding panels, and the polyisocyanurate (PIR) insulation boards, it was the ACM panels that have generally been thought – probably rightly in my view, as I have argued previously – to have been the primary cause of the disastrous rapid spread of the fire over the external surface of the building.
The Government acted with commendable speed and efficiency by requiring Local Authorities and Housing Associations to identify by end of day 19 June any ACM panels in use on their high rise buildings, and to send in samples for testing.
In its letter to the Chief Executives, the Department for Communities and Local Government (DCLG) claimed that to be compliant with ‘Building Regulations guidance’, the core of the panels should be composed of a material of ‘limited combustibility’, as defined in Approved Document B2 at Table A7, or be Euro Class A2 or better:
I outlined the Approved Document guidance for cladding systems in an earlier post. In brief, in AD B2 at 12.5, two routes to compliance are offered:
i) through adherence to the requirements of sub-sections 12.6-9 or;
ii) through large-scale system testing to BS 8414.
The DCLG, in its letter, was in effect assuming that the second route had not been taken, so that it was the requirements of 12.6 to 12.9 that were to be satisfied. In summary, 12.6 specifies that:
external surfaces over 18m should be national Class 0 or Euro Class B or better;
while 12.7 requires that for buildings over 18m:
insulation products, filler material etc should be of ‘limited combustibility’ as defined in the Table A7 mentioned in the DCLG’s letter. A material or product must either be 99% or more inorganic, or pass a 750° C furnace test (BS 476 part 11 or part 4), or have an incombustible core, or be Euro Class A2 or better.
I concluded in an earlier post that of the two main components of the Grenfell Tower system, only the Celotex RS5000 insulation boards were in breach of the Approved Document guidance, since it was only these that were covered by 12.7. The Reynobond PE cladding panels, not being an insulation product, and having a Class B rating, were in compliance with the relevant section, which is 12.6.
It is easy to see the difficulty for the government of admitting that the polyethylene cored cladding panels were compliant with the Approved Document guidance. It had been their responsibility to ensure that the regulations were fit for purpose and did not permit dangerous products to be used. These panels were certainly dangerous, in the use to which they were put. If a way could be found to assert that the regulations did not in fact permit the panels to be used, then this could potentially allow them to escape culpability in this regard.
Moreover, it was no doubt felt to be imperative to get any similar panels off the nations high rise buildings as soon as possible. It would probably be easier to force immediate action if the panels could be deemed to be non-compliant with the official guidance, than if it were admitted that they had been designed and installed in accord with it.
It is not particularly surprising, therefore, that the DCLG is currently pretending (if I may be so bold) that combustible ACM panels are in breach of the Approved Document guidance. In this post, I critically analyse the ways in which the Department has attempted to justify their position.
Continue reading Grenfell Tower: why the ACM panels were in compliance with the building regulations.