Non ACM cladding does ?not pose same threat?

Inside Housing reported on the government’s release of ‘long-awaited’ tests on a range of cladding materials, and its conclusion that ‘none pose the same threat as’ ACM, with the testing commissioned by the government and undertaken last summer by the Building Research Establishment (BRE), the report summarising results of tests on HPL, timber, zinc, copper and aluminium honeycomb cladding panels.

It found that none of these products ‘show the same or a similar type of fire performance to that’ of the polyethylene cored ACM panels used on Grenfell Tower, but BRE ‘recommended’ further testing of ‘more dangerous’ cladding products. The news outlet noted that the results come ‘just days’ after a privately commissioned HPL BS 8414 test that failed ‘in just seven minutes and 45 seconds’, with industry experts criticising the government for ‘failing to prioritise’ HPL cladding removal.

Inside Housing surmised that the release of the test results ‘would appear to be an attempt to rebut that criticism’, with 22 cladding combinations tested including untreated timber and standard grade HPL. Though guidance ‘would not permit’ the products to be used on external walls of tall buildings, they are in use on ‘hundreds’ of systems nationwide, with the summary finding that those two particular products showed ‘sustained vertical fire spread’ in tests.

However, the report added that HPL ‘released three times less heat’ than ACM, and recommended further testing to ‘help understand the impact’ of different fixing method types and insulation types. Zinc composite cladding with a fire retardant core ‘exhibited the highest contribution to fire growth’ and the ‘shortest time to burn through’, but still performed better than ACM in terms of fire growth and spread – with this combination originally specified for use on Grenfell.

The government did not test polyethylene cored zinc ‘as it was not possible to procure such panels for this project’, and the report concluded that if it had been tested, it may have performed similarly to ACM. Copper cladding meanwhile displayed ‘the most significant cavity fire and the largest measured heat flux’, but was also not polyethylene cored. Conversely, aluminium honeycomb, reconstituted stone and brick slip all displayed a ‘relatively low contribution to fire development’.

In its summary, the government repeated its advice that standard grade HPL should be removed from buildings as it was ‘unsafe’ and did ‘not comply with building regulations.