Understanding and implementing regulations, and third party certification, is essential to fire safety
If we have learned anything from Grenfell Tower it’s that architects need to have a thorough understanding of the Approved Document B (ADB) and, depending on the fire design route taken, of BS 9999 and BS 9991 from feasibility stage. We need to ask basic questions, such as: Are fire escapes positioned correctly? Will you be adopting a fire engineering route? We want simple guidance to help us at the early stages because at the moment there’s so much out there that it’s difficult to interpret it all in a holistic way.
Within a few days of the fire one of our directors asked me to prepare a practice guidance note on ventilated rainscreen cladding in light of the inferno. His request had me analysing the guidance in ADB more thoroughly and it is confusing. It talks about Class 0 ‘Surface Spread of Flame,’ so does not necessarily concern the properties of the composite material as a whole. As things stand, the material itself can be combustible and still meet Class 0 requirements. Diagram 40 of ADB, in describing the 18m rule, refers to Class 0 and sits at the root of the confusion.
As ADB contains definitions of non-combustibility and limited combustibility and Class 0, we have to work with them. Non-combustible or limited combustibility materials are defined in Tables A6 and A7 of Appendix A in ADB, to national class (BS 476) and European class (BS EN 13501) respectively. However, a footnote in those tables states that the national and European classifications don’t automatically equate. As we get a lot of materials from Europe, and to avoid confusion, the firm now works solely with the European classification and looks for test results to BS EN 13501.
BS 8414 is a test standard for cladding systems and contains no pass or fail criteria. Such criteria are described in BR 135 but that means you have to look at two documents. BRE has carried out BS 8414 tests for a group of manufacturers which have allowed it to list the results on its website. However, such tests remain commercially sensitive for many and architects often need to get the reports direct from manufacturers and check them themselves. Some manufacturers may resist but we should insist on seeing a report or go to another company who will divulge it. It’s critical to know the precise system tested, so that if it’s specified the contractor can’t deviate from it.
The biggest issue is dealing with contractor proposals for alternative materials and construction. Chapman Taylor employs technical staff like me to interrogate proposals and assess their suitability. I recommend that architects stick to specifying non-combustible or limited combustibility materials; when writing specifications I advise always using the word ‘equivalent’ rather than ‘similar’. I believe that introducing sprinkler systems, including in refurbishments, would be a good thing. However adding such active systems, or passive ones such as a secondary escape, could affect financial viability.
More needs to be done with third party certification of materials and workmanship regarding fire. This applies particularly to firestopping and I’ve changed our specification to follow Association for Specialist Fire Protection guidance and to require certification of workmanship as well as materials. Reports have highlighted that Grenfell Tower’s ‘certified’ 30-minute fire rated doors weren’t fit for purpose, but at some point certification has to be trusted – you can’t test every door. Before Grenfell, British Board of Agrément certificates for aluminium composite material (ACM) weren’t helpful regarding fire performance, and I’d advise architects to thoroughly scrutinise BBA certificates with respect to both this and material properties before selecting products. On-site workmanship remains a bugbear that’s difficult to control and will only be dealt with by something like the return of the Clerk of Works role.
We’ve accepted desktops studies in the past but admit they can be questionable depending on who they’re produced by. This needs to be rigorously addressed in much more depth – perhaps via a formal British Standard. Studies should be carried out by a fully independent testing organisation and published; this would accord with the Hackitt review’s recommendation to put testing in the public domain but it brings us back to the realms of commercial sensitivity – if the client’s paid for it, it has a say on whose sees it.
The hard fact is that cost implications creep into the process. Non-combustible materials like mineral wool are up to 30% thicker than PIR and PUR, which affects the GIA, so a client that is driven by profit will tend towards the latter. That said, sprinkler systems might knock out a floor so choosing non-combustible cladding might be the better option in high value developments. In preparing the report Dame Judith has had pressure from all sides – insulation companies, the RIBA, fire authorities, testing bodies, the Sprinkler Alliance. By not being prescriptive, the report’s findings could give the market the leeway to decide the best way forward.
The biggest issue is dealing with contractor proposals for alternative materials and construction
I’ve always said that you shouldn’t scrimp on structure, waterproofing or fire safety – but above all fire. Architects need to rely on robust designs and not merely trust a certificate from building control as evidence of compliance – building control officers may be inexperienced and are not infallible. It seems each side expected the other to discharge responsibilities and something fell down the cracks. We need to be more vigilant in ensuring that our design intent is compliant and followed through. But it’s not just building control – we need a conversation with clients and contractors too. One thing in the Hackett report that caught my eye was that it was mainly architects and enforcement agencies accessing current approved documents – not contractors or project managers.
Judith Hackitt used to be head of the HSE and is suggesting criminal liability being applied to regulations as for CDM. While the Health & Safety at Work Act is part of criminal law I’m not sure the Building Act is, so how criminal liability will be brought to bear on it I don’t know. The potential knock-on effects of changing fire policy are enormous and I sense the government won’t react until after Brexit in March 2019 so as not to destabilise the construction industry. In the meantime, the RIBA could lead on this voluntarily although until it’s legally enforced clients won’t respond to it. That said, we’ve noticed some clients are becoming more risk averse, asking us to look at projects again and footing the extra cost to upgrade their specification, so the penny seems to be dropping.
Under the current framework, if a client wishes to demand reduced or compromised compliance against our professional recommendation we’re going to have to insist that they instruct us and take full responsibility for the implications of that demand. Ultimately, the profession has to be more robust with clients and contractors, more rigorous and self-policing – that is the very least the Grenfell tragedy demands of us.
Mike Kirby is associate director in the technical group at Chapman Taylor’s London studio, advising project teams on specification, technical, construction and building legislation issues