UK government proposes 11m threshold instead of 18m for non-combustible wall constructions

The UK government launched a consultation on 20 January 2020, in which it proposes an 11 metre – rather than 18 metre – threshold in relation to non-combustible external wall materials. Specifically, if a residential (including partially residential) building has any floor height above 11 metres, then the entire external wall will need to be constructed from non-combustible materials (classified as A1 or A2 when tested to the EN standard for Reaction to Fire), reported TRADA.

The scope of which building types could be affected is proposed to increase and include hotels, hostels and boarding houses, which were previously exempted.


This will effectively limit the construction of residential buildings to 4 storeys where the wall or cladding includes materials like timber, which cannot at present meet this very high standard of fire performance.

Full details of the consultation, entitled ‘Review of the ban on the use of combustible materials in and on the external walls of buildings including attachments’ can be found here. The consultation runs for 12 weeks and submissions need to be in by 13 April 2020.


According to TRADA, while this proposal is not entirely unexpected – something broadly similar has been in place in Scotland for a while – it is certainly very significant for the construction industry.

TRADA notes that the document itself is quite explicit in paragraphs 28 and 31 in stating that there is no clear scientific or research-based evidence to support the government’s proposal. The approach is to ‘reduce the height threshold to 11 metres now, and commission research to allow further review of the height threshold’ as the option that best provides public protection.

TRADA’s overarching comment on this at this point is that there needs to be very careful handling of this debate. “If we deviate from a philosophical approach that is built on the foundations of arguments backed up with evidence and logic – which is what is being proposed – we are going to find it very difficult to progress in an orderly manner with this consultation, subsequent changes and the many consequences that follow. We would, therefore, like to see all necessary and relevant research in this regard begin urgently,” said TRADA.