Mark Chalmers

While legislators down south wrestle with how to implement Judith Hackitt’s Golden Thread, the aftermath of the Grenfell Tower fire is being felt in Scotland, too.

In her Building a Safer Future report, which was published in the wake of the fire at Grenfell Tower in London, Hackitt recommended the introduction of a “golden thread” to ensure that building safety is taken into account at every stage in a building’s lifecycle.  At first, it wasn’t clear how that would work in practice, but it turns out that the impact is far reaching.  Even though the requirements of the Scottish Technical Standards are seen as being slightly tougher than those down south, and the Building Control system here is more strictly applied than the third party verifier model used to date in England, they have lots of things in common.

Fundamentally, we buy the same materials and products manufactured by the same corporations and sold by the same merchants. Despite the fact we practice in Scotland and are not directly affected by Hackitt’s report, we’ve discovered that it's no longer enough to state that a material complies with the relevant standard. Now we also need to produce fire test certificates for everything we specify:

• Intumescent paint
• Fire-rated windows
• Fire doors, of course
• Sandwich cladding panels
• MF partitioning systems

I’ve always tried to avoid sandwich panels, due to their lack of fire resistance, the plastic foam insulation inside each one which is environmentally nasty thanks to the blowing agents used in its manufacture, and the near impossibility of recycling panels at the end of their life – but we’re sometimes forced to use them, to meet a client’s branding requirements. American motor manufacturing corporations even have a habit of specifying US cladding products which simply aren’t available here – and even if they were, they wouldn’t meet our standards because they haven’t been fire tested in the UK.

However the last category, MF partitioning, has proven to be the trickiest. Over the past two or three years, manufacturers have quietly re-tested and re-badged all of the walltypes in their White Book, Green Book or Pink Book.  Suddenly, internal wall constructions which we’ve used for years to achieve 60 minutes at 6 or 7 metres high, no longer comply.  As a result, all the internal wall constructions which we specified during the Covid era, marked up on the walltypes drawing, then detailed, have had to be revised. 

Where we can’t get Warrington fire test certificates for particular build-ups, such as the fire-resistant “umbrella” where a compartment wall head hits an existing sandwich panel roof, we needed to get fire engineering assessments which took much longer than we expected.  Then we discovered that one of the major plasterboard firms no longer markets horizontal Shaftwall, which is proved to be an acute hassle since it’s essential to form the fireproof lid over the fire escape stair enclosures, if you’re to avoid using wet trades and heavyside materials. So now we have a mix-and-match building, using systems from rival manufacturers, which won’t greatly please the contractor’s buyer.

I guess that’s one difficulty of working on refurbishments of modern commercial sheds, which I’ve had to do once or twice recently – rather than taking either an older industrial building with a concrete frame and brick walls, or designing a newbuild on a clean sheet of paper. The older industrial is bombproof: the frame and walls are inherently fire resistant and will achieve 4 or more hours of fire resistance, effortlessly. The newbuild can be engineered to do whatever’s required from the outset.

Unravelling the Golden Thread means that more product information is needed at an earlier stage of the scheme, and each Building Warrant application becomes a larger package which takes longer for the BCO to assess – and at the very end of the project, O&M manuals will grow to be two or three times their current size.  Architects, structural and fire engineers have to put together a narrative, telling the story of how they struggled to make relatively modern retail sheds and warehouses comply, and documenting the increasingly complex systems they needed to do it.  However, if that saves even one life, it's a price worth paying.