So far as I am aware, PE cored ACMs have never been successfully tested in a cladding system in a manner consistent with building regulations so it is hard to understand how this product ever ended up on Grenfell Tower. Similarly, given the fire performance characteristics of these ACM cladding panels, it is no surprise in my view that they performed so poorly in combination with a range of insulation types in the recent series of large-scale tests by DCLG.
Trusting in simplistic classifications for materials based on small scale testing (such as Euroclass categories or a ‘non-combustible’ label) is not the solution. The reality is that a whole range of factors will affect fire safety, including the design of cavity barriers, fixings used and cavity width. We must improve our knowledge base of how all these different elements interact. As any fire expert knows, even ‘non-combustibles’ are still capable of burning and, in isolation, are no guarantee of what constitutes a fire safe building.