A second cladding system has been found to meet building regulations guidance, although no UK buildings are known to have it.
Following the fire at Grenfell Tower on 14 June, the government initiated a fire safety testing programme led by the Building Research Establishment (BRE). Hundreds of aluminium composite material (ACM) cladding samples have been tested for compliance with fire safety guidance set out in the Building Regulations 2010. Five large-scale cladding combinations have also been tested.
On Friday the fourth large-scale cladding system because the first to meet building regulations guidance. Thirteen UK buildings are known to have the combination, which is a combination of ACM cladding with a fire resistant polyethylene filler – category two in screening tests – and a stone wool insulation.
Yesterday (Monday) a fifth test showed that a second cladding combination has passed the BRE-led tests. It examined a combination of ACM cladding with a limited combustibility filler, which was category one in screening tests, with PIR foam insulation.
Although the government is not aware of any UK buildings with this cladding combination, the Department for Communities and Local Government said it could provide a solution for buildings which currently have a failed cladding combination.
Around 269 ACM cladding samples have failed since the testing programme began, and the first three large-scale cladding combinations also failed. An independent review of current building regulations and fire safety in tall buildings is to be carried out as a result, led by EFF chair Dame Judith Hackitt.
The large-scale tests involve building a 9m high structure and then burning the cladding system to test how fire spreads across its surface. The tests are carried out as advised in British Standard 8414-1, and the results are then classified according to criteria detailed in BR135. This is the second route to compliance with Building Regulations 2010 fire safety guidance; seven tests will be carried out in total.
The government’s Independent Expert Advisory Panel, led by BRE chief executive Peter Bonfield, cautioned the cladding combination would only comply when installed and maintained properly.