The UK’s largest and most influential building control body has produced guidance allowing the use of combustible coatings on high-rise buildings to reduce its workload, the Grenfell Inquiry heard.
John Lewis, a fire engineer at the National House Building Council (NHBC), told Wednesday’s hearing that checking each cladding system for non-compliance was taking too long.
In 2016, a year before the Grenfell fire, NHBC introduced guidance approving in principle the use of aluminum cladding panels in exterior walls without requiring a fire test or ‘desk study’, provided that they meet certain minimum specifications.
Asked by lawyer Richard Millet QC what the advice was for, Lewis said: ‘It was just that at the time NHBC realized that the processes we were going through were very time consuming.
He said “all my time was on them”, as well as his colleagues’ time, adding, “There was, you know, the desire to move more to, you know, the status quo.”
Two years previously, NHBC had helped draft guidelines allowing the use of combustible materials in lining systems as long as they were signed by an expert with a desk study.
This was a departure from previous practice which only allowed ‘limited combustibility’ materials or materials that had passed a full-scale fire test for use on buildings over 18m in height.
Processes for showing compliance of combustible materials in these projects have been called “Option 3” by the Building Control Alliance, an industry group representing building control professionals.
Lewis said the 2016 document, which further watered down previous guidance, was meant to be a “streamlined Option 3”.
Millett said: “Well, it was a simplified option 3, which meant you didn’t have to do anything with the things that [building regulations] required or suggested.
Lewis replied that option 3 “didn’t necessarily mean you had to follow” building regulations, but did mean you write a report that the proposed facade system, if tested, would “probably” meet them.
He was then shown a response previously heard in the survey from Stuart Taylor, an engineer at facades specialist Wintech, in which he said the 2016 NHBC guidance note “in no way resembles” the building regulations and was “pretty irresponsible”.
Asked by Millett if he agreed with the assessment, Lewis replied: “We didn’t want to be irresponsible. We were, you know, trying to do things better.
“You know, that implies we were pretty blasé about it. It certainly wasn’t. But other than that, I think what he says is probably true.
Millett then asked Lewis: “Let me suggest to you that his characterization of this memo as completely irresponsible or utterly irresponsible is correct, and it was a dangerous mistake on the part of NHBC designed to get back to business as usual and at the expense of personal safety. What do you say to that?
Lewis replied, “I agree it shouldn’t have been written.”
The inquest then heard testimony from Lewis’ colleague, Diane Marshall, who currently works as NHBC’s director of operations.
She said the NHBC initially accepted the use of Kingspan K15 insulation, a combustible product believed to have been used during the refurbishment of Grenfell Tower, based on a certificate issued by the British Board of Agrément (BBA).
The BBA has previously admitted that the certificate was “misleading” and that the body had made a “very basic lack of due diligence” in producing it.
Marshall said she “sees no reason to challenge the credibility of the certificate” because the reputation of a BBA certificate is “well regarded” in the industry.
Millett asked, “Even if it says the moon is made of green cheese?”
Marshall said the BBA was “unlikely” to make such a statement, to which Millett replied: “Why is it more unlikely to make that statement than a statement that a [combustible] insulation product could be authorized beyond 18 meters? Marshall said, “That’s probably a question for BBA.”
NHBC had no role in the refurbishment of Grenfell Tower which killed 72 people in June 2017, but it has signed up more than half of the UK’s residential schemes.
The investigation is continuing.