Flammable insulation chosen for Grenfell Tower as part of a focus on eco-friendliness

Combustible Celotex RS5000 insulation selected to meet ‘thermal performance’ target, says chief architect

Flammable insulation was chosen for the Grenfell Tower refurbishment as part of a focus on eco-friendliness, the inquiry into the blaze has heard.

Bruce Sounes, chief architect for the firm Studio E, said the combustible Celotex RS5000 insulation was selected to help meet a “thermal performance” target for the block set by the “aspirational engineers” Max Fordham.

The engineers had set a so-called U-value target of 0.15 for the insulation, a measure of energy efficiency, which exceeded what was required for existing buildings and was the standard for new-build homes, the inquiry heard.

Another Studio E architect suggested in internal correspondence that Max Fordham had opted for an “ott” U-value to “achieve maximum credits available for thermal performance criteria”, according to documents submitted to the inquiry.

The target prevented the use of Mr Sounes’s first choice material of rock wool, which he told the inquiry was “the safest in terms of fire”.

But he said he “couldn’t see any reason to abandon the target”, adding: “It was in the project’s interests to try and achieve it.”

Mr Sounes said he did not have concerns about using the foam Celotex as at the time “these type of products were widely used”, adding: “At the time, I was of the view that Celotex didn’t burn it just charred and it was safe to use in cavities.”

He added: “With hindsight obviously no-one challenged the insulation.”

Mr Sounes said: “We have done a lot of work with Max Fordham and they pride themselves as aspirational engineers ... they have done exceptionally sustainable buildings.

“The emphasis on passive sustainability was something we shared with Max Fordham over a number of years.

“I couldn’t see any reason to abandon 0.15. It was in the project’s interests to try and achieve it.”

The inquiry has previously heard from a lawyer for the survivors and bereaved families of the tragedy that an “overfocus on sustainability ... literally fuelled the inferno which ensued”.

Stephanie Barwise QC told the inquiry in January that the design team wanted to win an annual award for the most “innovatively sustainable” buildings, known as a BREEAM (Building Research Establishment Environmental Assessment Method).

She said: “Given the current environment imperative, the drive to reduce carbon emissions was laudable, but it is perhaps an opportune moment to reflect on the fact that at Grenfell, at least, that drive very directly led, with much encouragement from the insulation manufacturer, Celotex, to the use of combustible insulation behind the rainscreen cladding which fuelled the inferno which ensued.

“The use of combustible insulation resulted in fires of much higher temperatures than they otherwise would be – and so it was at Grenfell.”

PA