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Insulation used on Grenfell Tower failed a fire safety test on an occasion where officials were not following safety instructions, an inquiry has heard.
Flames spread up a rig containing Kingspan’s Kooltherm K15 product and were allowed to keep burning after they climbed above the top of the equipment during a test at the Building Research Establishment (BRE) in 2014.
This was despite documentation from the British Standard which stated a fire test should be terminated early if flames spread above the top of the testing rig, or if staff were in immediate danger.
Footage of the 2014 test and the documentation were shown to the Grenfell Tower Inquiry as the BRE’s former cladding test chief supervisor, Philip Clark, began his third day of evidence on Thursday.
Mr Clark suggested ignoring that standard was common practice in the fire testing industry and his “main criteria for terminating” a test was the risk to staff or equipment.
He told the inquiry: “This had always been common practice from day one every single test I’ve ever performed with me or other people that has always been the way and carried on in that regard.”
The BRE not terminating the test in line with the rules did not cause K15’s test failure.
Mr Clark went on: “If we deemed it to not be unsafe we would allow that system to carry on burning so that knowledge could be gained from how it performed in other ways.
“That has always been the practice I’ve always done it’s always been with every other person that’s ever run a test in the whole of my career.”
Pushed further on why it was allowed to keep burning Mr Clark said: “Failures are as valuable as passes.”
“If you just terminated everything you would never learn anything and no progress would ever be made.”
Mr Clark said if a rig was allowed to keep burning in this way it would not go on and pass, and the “termination point” would be noted in the report following reviews of footage and notes.
As Mr Clark came to the end of his evidence on Thursday he was given the opportunity to say whether he wishes he could change any of his actions.
He told the hearing: “I never wanted to be in a position where what we have done has caused such a disaster.”
The majority of the insulation used on the west London tower block was made by Kingspan’s rival firm Celotex.
The inquiry is examining how Grenfell Tower came to be coated in flammable materials which contributed to the spread of flames which shot up the tower in June 2017, killing 72 people.