The Government has recently issued updated and consolidated advice for owners with these types of buildings, based on the outcomes from the testing programmes undertaken by the Building Research Establishment to identify whether ACM cladding meets the limited combustibility requirements of current Building Regulations guidance.

A link to the full report is included here, but expert advice is that:

ACM with an unmodified polyethylene filler (category 3 in screening tests) with any type of insulation presents a significant hazard on buildings over 18m;

It is possible that ACM with a fire retardant filler (category 2 in screening tests) could be used safely with non-combustible insulation (such a stone wool), but it is highly dependent on the insulation used, and how it is fitted;

ACM with a limited combustibility filler (category 1 in screening tests) can be used safely, although this is dependent on how it is fitted;

Building owners should take professional advice on further action with regard to their cladding system and follow advice issued on interim fire safety measures.