I HAVE read Iain Barclay’s letter concerning the possible contribution of uPVC windows to the horrendous fire at Grenfell tower last week (Letters, June 20).
I have debated whether to comment on the cladding. I have also avoided researching the company that made it or its technical statements on the performance. I suspect that thermal efficiency and appearance will have been the main choices with reaction to fire: a box ticking exercise.
There are exacting EuroNorm standards for testing every aspect of a product and constructed systems for performance, the most onerous involving large-scale test work at accredited laboratories. In my working life I organised more than 20 such tests for my employer so, without going into technical detail, let me explain the following.
Aluminium expands rapidly when subjected to high temperature and smelts at around 660°C. The outer metal skin of the composite panels will detach, exposing the polyisocyanurate foam core.
This material will have fire retardation additions in its composition but, exposed to air and at the temperatures reached, it will burn. This also adds emphasis to Iain Barclay’s point about the windows
I have also noted the inspection of the cladding on the Ayr multi-storey block on BBC Scotland News. I could tell that the weather skin was a fibre cement board and the insulation is a high-density, rock-fibre product, both rated “non combustible”.
I know that many refurbished multi-storey blocks on Scotland follow this specification. I would hope that all local authorities maintain records of specifications for all refurbishment to all properties, especially high-rise housing. I was involved in the cladding of the Cineworld complex in Glasgow and, while the outer cladding is aluminium, all of the insulation and steel substructure is non-combustible.
In the stair well above Renfrew Lane the cladding was tested and certified to give four hours of resistance from both inside and outside when the Scottish Building Standards required two hours. I organised and witnessed the test at the Warrington Fire Research centre on behalf of my employer and in liaison with Glasgow’s Building Control department. I mention this to give peace of mind concerning this particular high rise building.
I hope that my observations help to endorse Iain Barclay’s letter concerning the windows possibly used at Grenfell and illustrate the connection between them and the cladding’s fire performance.
Ian Gray,
Low Cottage,
Croftamie.
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