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Experts blame cladding for spread of Grenfell blaze

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Fire experts have told a public inquiry into London’s Grenfell Tower tragedy that combustible cladding was the “primary cause” of the blaze’s spread.

The 1970s tower was fitted with aluminium composite cladding – a Reynobond 55PE product supplied by US giant Arconic – during a recent refurbishment.

Leading fire safety engineer Barbara Lane told the hearing the cladding was incorrectly installed and resulted in the “catastrophic” spread of the blaze, which killed 72 people last June. She believes the fire, which started in the kitchen of a fourth-floor flat, spread to the exterior through a newly installed window.

Luke Bisby, an expert in fire and structures at the University of Edinburgh, agrees.

“The fire most likely spread to the cladding via gaps or holes that formed in polymeric window framing boards that surrounded the kitchen window, and also through the weatherproofing membrane and thermal insulation – all of which were installed during the 2012-16 refurbishment,” his report says.

“The fire most likely then penetrated into the back of the cladding cavity and ignited the polyethylene filler material within the aluminium composite material (ACM) rain-screen cladding cassettes that form the majority of the building’s exterior surface.

“The primary cause of rapid and extensive external fire spread was the presence of polyethylene-filled ACM rain-screen cassettes in the building’s refurbishment cladding system.”

Jose Torero, a fire safety expert at the University of Maryland, says drastic changes in approach are required.

“The tragic consequences of the Grenfell Tower fire highlight the significant shift in complexity that occurs when intricate facade systems are incorporated into high-rise buildings,” his report says.

“Functional requirements, guidelines and simple standardised tests become insufficient tools to establish adequate performance of systems where performance is a function of the interactions of the building and building envelope.

“There is a need to shift from a culture that inappropriately trivialises compliance to a culture that recognises complexity in compliance and therefore values competency, performance and quality.”

Lawyers for Arconic argue their product was not the main cause of the tragedy. They say it was not Arconic’s decision to use the panels on the tower, and the way they were used was not its responsibility.

They argue that had windows been correctly constructed, the fire could have been contained.

“We submit that the evidence does not justify the conclusion that the cladding panels supplied by the company were anything other than, at most, a contributing feature to the fire,” the lawyers’ opening statement says. “The panels did not render inevitable the catastrophe.”