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The type of cladding panels fitted on Grenfell Tower performed “spectacularly worse” in fire tests than a sister product despite being marketed under the same fire safety certificate, the inquiry into the disaster has heard.
Reynobond PE (polyethylene) cladding panels came in two variants, “cassette” and “rivet”, but the differences between their fire performance was “very great”, the inquiry heard on Tuesday.
According to 2004 tests, the cassette panels burned faster and released around seven times as much heat and three times the rate of smoke as rivet panels.
A regulatory document issued by the British Board of Agrément in 2008 made no distinction between the types of panels and the cassette form was ultimately chosen for the Grenfell refurbishment, the inquiry heard.
Inquiry chairman Sir Martin Moore-Bick has already found the “principal reason” the flames shot up the tower at such speed was the plastic-filled aluminium composite material cladding panels acting as a “source of fuel”.
Claude Schmidt, current president of the French division of the multinational firm Arconic, which manufactured the Reynobond panels, agreed the differences between cassette and rivet were “very great” in the 2004 fire tests.
Inquiry lawyer Richard Millett QC asked him: “These are not small differences, are they? The differences in results between rivet and cassette are very great.
“Do you accept that the cassette, according to these tests, performed spectacularly worse than the rivet?”
Answering through a translator, Mr Schmidt agreed.
According to the 2004 tests, the Figra (fire growth rate) for the rivet panels was 105.5 watts compared with 1,009.2 for the cassette. The rivet had a THR (total heat release) of 7.8 megajoules compared with 59 megajoules for the cassette.
The Smogra (smoke growth rate) was 5.7 for the rivet compared with 16.6 for cassette.
The 2008 BBA certificate used to sell Reynobond panels did not distinguish between the variants and effectively presented both as having a rating of Euroclass B in fire tests.
The cassette variants achieved no rating in the 2004 tests and eventually achieved the second lowest classification of Euroclass E in 2010 tests, proceedings heard.
Mr Schmidt accepted the BBA certificate contained a “false statement” by not differentiating between the panels.
Asked if he could explain “why that false statement was made”, he said: “No, I can’t say that at all.”
“I can’t say because I was not involved in drawing up the BBA certificate. That was the responsibility of the technical service and I don’t know why that was not communicated directly.”
In his witness statement, Mr Schmidt said: “As I have explained, I was not involved in obtaining a BBA certificate for Reynobond 55 PE and FR, and do not deal with such certificates myself.
“As such, I cannot provide a detailed explanation of that certificate.”