Grenfell Tower cladding fire dangers known about for decades, inquiry told
The dangers of the flammable material used in the cladding panels on Grenfell Tower have been known for decades, an expert has said.
Professor Luke Bisby concluded the primary cause for the “rapid and extensive” spread of the blaze up and around the building was the presence of polyethylene (PE)-filled panels.
The fire expert said the material, on exposure to heat, will “melt and drip – possibly flowing whilst burning or generating flaming droplets”.
In a report prepared for the public inquiry into last June’s disaster, which killed 72 people, he said the reaction to fire of PE is written about in decades-old literature, including publications from 1975 and 1976.
Prof Bisby told the inquiry, in central London, on Wednesday he would be surprised if fire safety professionals were aware of the specific papers.
But he added: “The general principle that a thermoplastic will melt and drip and burn quite vigorously is very clearly highlighted in any of the reference texts that one would expect a competent fire safety professional to have at least skimmed if not know quite well.”
Counsel to the inquiry Richard Millett QC suggested there has been a body of opinion since 1988 “of the dangers of thermoplastic materials from a safety perspective”.
The professor of fire and structures at the University of Edinburgh replied: “Absolutely.”
The inquiry heard the Reynobond 55PE aluminium composite material (ACM) panels, also referred to as cassettes, which formed the outer shell of Grenfell’s cladding system following a refurbishment completed in 2016, left PE exposed.
Mr Millett asked: “Does that mean any flame emanating from the window set could get up through that crack and melt or burn the exposed PE?”
The witness said: “Absolutely.”
The inquiry has heard how a small kitchen fire which broke out in Flat 16, on the 24-storey building’s fourth floor, took around 11 minutes to spread to the outside.
Prof Bisby said he believes the fire spread to the cladding through a hole in the window or out though the materials in the side or around the surrounds of the windows.
He agreed it was “likely” that if there was a fire anywhere near the window it would break out of the window and into the cladding.
Video footage, submitted as evidence by Prof Bisby, shows the blaze taking hold before spreading up the east side of the tower as debris rains down.
“In my opinion, the primary cause of rapid and extensive vertical and horizontal external fire spread was the presence of polyethylene-filled ACM rainscreen cassettes in the building’s refurbishment cladding system and in the architectural crown detail,” the expert concluded in his report.