A government consultation into a 2018 ban on the use of combustible materials in and on the external walls of buildings has sparked a fierce debate between the timber lobby, architects and the concrete industry.
In an amendment to Building Regulations that came into force in December 2018, the government banned the use of combustible materials anywhere in the external walls of high-ride buildings over 18m that contained one or more dwellings. The ban applies to new buildings and to refurbishment work where an external wall is involved.
In its review of the ban, launched in January this year as part of its review of building safety, the government called for views on the ban, including the types of buildings covered and their height, as well as possible exemptions, in a consultation.
It has been suggested that the government could end up extending the ban down to 11m – a proposal that met strong opposition from the Timber Trade Federation (TTF), which warned that such a ban on the use of structural walls of buildings would have a series of negative impacts on modern methods of construction (MMC), sustainability, and housing targets.
The TTF said: “The best way to improve this legislation would be to focus any extension of a ban on combustible materials down to 11m on the external cladding, not the structural wall itself.
“Making such a change to the ban would also bring us into line with regulations in Scotland, which banned combustible cladding above 11 metres, but does not include the structural wall in the scope of the ban."
It added: “The best way that the government could achieve a safer building system is by introducing mandatory, comprehensive fire-risk assessments during the design process for buildings such as high rises, communities and schools.
“We support stronger enforcement in the form of a new Building Safety Regulator, and the introduction of mandatory sprinklers, two escape stairs, and other fire safety components into high rise buildings, unless shown to be unnecessary by a comprehensive fire risk assessment.”
But the Mineral Products Association’s (MPA) UK Concrete division urged the government not to “U-turn” on proposals to ban all combustible materials in the external walls of buildings over 11m.
Chris Leese, UK concrete director, said: “The proposed new guidelines relate to external walls and will make a dramatic contribution to reducing the spread of fire and addressing the potential dangers of buildings with combustible materials such as timber. Once a combustible structure becomes involved in a fire, this adds significant fuel and increases the chances of compartmentation failing and the fire spreading and ultimately potential for collapse.
“Conversely, concrete and concrete products help to keep people and properties safe by minimising fire risk as a result of their inherent material properties.”
And he dismissed arguments from the TTF that banning timber in structural walls would impact the government’s sustainability targets. He said: “Concrete and concrete products are being used to construct buildings that have a low environmental impact due to better whole life performance through superior energy efficiency and reduced maintenance requirements over their long lifetimes.”
The Royal Institute of British Architects (RIBA) recommended that the combustibles ban should be extended to include hotels, hostels and boarding houses. It also called for the ban to apply to key materials in external walls only, and if not then for the list of materials exempt from the ban to be clarified.
But it did not recommend that the ban should include the primary structure of the building, and called for further research into the use of structural timber within external walls – for example cross laminated timber – to determine performance when subject to real fire loads.
It also recommended that the ban be extended “on a precautionary basis” to include relevant buildings with a storey over 11m above ground level.
Jane Duncan, chair of the RIBA Expert Advisory Group for Fire Safety, said: “Almost three years on from the Grenfell Tower tragedy, hotels, hostels, boarding houses and other buildings with multiple and even vulnerable occupants are still being built using combustible materials on their external walls. Fires do not discriminate between building types or users, yet our regulations do. The restriction on combustible materials must be extended as a matter of urgency to keep people safe."
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