Last week the government launched its long-awaited consultation on proposed changes to its building regulations guidance document, Approved Document B. One option is to ban the use of desktop studies altogether, but is this the right answer? LGC’s sister title New Civil Engineer takes a closer look.
Government officials have been under pressure to change the guidance since the Grenfell Tower fire last year, as some experts believe the tower’s cladding had contributed to the rapid spread of the fire and questions have been raised as to whether and how the cladding was deemed to comply with building regulations. If the cladding was seen to comply with building regulations, it has led experts to ask whether the routes to complying with building regulations are robust enough.
Aluminium composite tiles which were used in Grenfell Tower’s cladding combination failed initial fire resistence tests carried out days after the fire had taken place. In July, the cladding combination understood to have been used on Grenfell Tower, ACM cladding with polyethylene filler and foam insulation, with fire breaks and cavity barriers in place, failed a large-scale fire test carried out by the Building Research Establishment. The test was part of a wider programme of cladding tests commissioned by the government.
At the moment there are four ways to comply with part B4 of the building regulations, which relates to fire safety of building facades. While three involve some form of physical test, the fourth route allows a desktop study to be carried out instead.
Dame Judith Hackitt, who is leading a review into building regulations which was set up following the Grenfell Tower fire, said government should “significantly restrict” the use of desktop studies.
In her interim report in December, she said: “The government should significantly restrict the use of desktop studies to approve changes to cladding and other systems to ensure that they are only used where appropriate and with sufficient, relevant test evidence.
“Those undertaking desktop studies must be able to demonstrate suitable competence. The industry should ensure that their use of desktop studies is responsible and in line with this aim.”
Two official options were put forward for the consultation. The first is to do nothing, i.e. make no changes to the document. The second is to make amendments to the document which would restrict the use of desktop studies.
But the government also said desktop studies could be banned completely. Launching the consultation, housing secretary Sajid Javid said: “We have listened carefully to Dame Judith Hackitt and we are taking action to strengthen building regulations guidance, which could mean that the use of ‘desktop studies’ are either significantly restricted or banned altogether.”
Is a ban the right answer? Fire Sector Federation built environment workstream chair Tom Roche cautions that desktop studies are an emotive topic, even among industry experts.
“It’s a little bit more complex than just a straight yes or no, there are a lot more dimensions to this that people need to consider,” he says, adding that the outcome – whether a cladding combination or material is deemed safe – must ultimately be the focus of any testing process.
“We’ve got to be clear that these products are safe for the purpose they’re intended to be used in,” he says.
“You have to be guided by that principle: will we deliver something that’s fit for the intended purpose, and doesn’t impact fire safety?”
Roche explains the Fire Sector Federation is still considering its position on allowing desktop studies; while many of its members would agree with banning the use of desktop studies, many would advise against it.
But Specialist Engineering Contractors Association chief executive Rudi Klein feels that a ban on desktop studies could work better than restricting their use.
“Rather than making exemptions, which I think can be used and abused, I’m all for saying, ‘actually, I think we should just do away with them [desktop studies]’”, he says.
However, Klein cautions clear definitions would have to be set for the ban. Using a desktop study to test materials with health and safety implications would not be acceptable; testing an individual material, such as a screw, could be tested with a desktop study as there would be less at stake.
Klein suggests materials could be labelled with what they should be used for, which would help users identify whether a desktop study could be used or not.
“All circumstances are different, aren’t they? All projects are different, all health and safety issues are different,” he says.
“It’s difficult sometimes to have a policy that’s all encompassing and applies to everything. But the trouble is, you start making exceptions and then people will find ways and means of getting round them.”
The consultation on changes to Approved Document B closes on 25 May.