The RIBA has responded to the UK government’s review of its 2018 restriction on combustible materials in and on the external walls of buildings, from the Ministry of Housing, Communities and Local Government (MHCLG).
Following the restriction on the use of combustible materials introduced in December 2018, the RIBA recommends that the restriction should:
- be extended to include hotels, hostels and boarding houses, and all buildings where a catastrophic event could cause multiple fatalities
- apply to key materials in external walls only, or the list of materials exempt from the ban must be clarified and should include all materials that do not contribute to the spread of fire across external walls*
- not include the primary structure of the building. Further research into the use of structural timber within external walls (such as cross laminated timber) should be undertaken to determine the performance of buildings constructed using structural timber when subject to real fire loads, so that the construction industry might benefit from the lower embodied carbon benefits that can be provided by the use of structural timber
- extended on a precautionary basis to include relevant buildings with a story over 11m above ground level, pending further research which should be undertaken to provide a deeper research base to determine the appropriate height threshold. Research should, include gathering intelligence from fire and rescue services
* The RIBA recommend that within external wall construction, the ban should only restrict plasterboard, sheathing boards, insulation, outermost cladding materials and significant materials in balconies, brise soleil, and similar building elements to European classification A2-s1, d0 or A1. The ban should not include the building's primary structure. The primary structure should have adequate fire protection, as set out in Building Regulations requirement B3 and when included in the external wall should still meet requirement B4. The RIBA recommend that if the MHCLG will not alter the ban to only include these materials, then the MHCLG should provide clarity on the list of materials that are exempt from the ban and should include additional materials that do not significantly increase the potential fire load of external walls.
Download the full response below.