Government guidance before the Grenfell fire “endorsed” the deadly cladding panels used on the tower, one of the inquiry’s expert witnesses has concluded.
Paul Hyett, an architect with more than 40 years of professional experience and a former president of the Royal Institute of British Architects (RIBA), said official guidance permitted the use of cladding with a ‘Class 0’ rating on high-rise buildings.
The Reynobond aluminium composite material (ACM) panels installed on Grenfell Tower had a certificate from the British Board of Agrément which said the panels “may be regarded” as having this rating.
“It is therefore my opinion that the guidance… endorsed, in principle at least, the use of the Reynobond aluminium composite panels for use on a project such as Grenfell Tower,” Paul Hyett wrote.
“It is my further opinion that most architects would have considered that such endorsement indicated that, in principle, the panels also met the requirements of the building regulations. That would certainly have been my conclusion.”
This has been a conclusion the government has vociferously resisted since the fire. It issued a clarification just eight days after the fire which insisted that composite cladding panels were required to meet the higher standard of ‘limited combustibility’ and branded the cladding on Grenfell ‘banned’.
The government said this was because of a reference to ‘filler material’ in its guidance, Approved Document B (ADB), which it claimed referred to the combustible polyethylene core of a cladding panel.
But Mr Hyett rejected this. “I do not think that the authors of ADB intended the term ‘filler’ or ‘filler material’ to mean any part of a composite material (eg aluminium composite panel) that is factory manufactured and delivered to site as a finished product,” he wrote.
“Rather, it is something (either solid (eg polystyrene), granular (eg sand) or fluid (eg mastic)) that is put into, squeezed into or poured into a host environment.”
This issue has been hotly debated since the fire, with some industry figures accusing the government of seeking to dodge liability for the cladding crisis by reinterpreting its guidance.
Ministers and officials had been warned since a select committee report in 1999 that the Class 0 standard needed to be tightened, including several written warnings following the Lakanal House fire in 2009, but no amendment was ever made to guidance.
Mr Hyett has not yet been questioned on this conclusion. His view differs from Beryl Menzies, an expert on building control, who advised last week that cladding should have been limited combustibility due in part to industry guidance other than Approved Document B.
Despite his conclusion on the cladding panels, he also said the use of combustible insulation behind the ACM cladding was clearly not permitted on a high rise. The insulation used – Celotex RS5000 – should have been “rejected from the outset as an insulation material suitable for use” on the tower.
Due to this and other errors, Mr Hyett said there was a “widespread failure” on the part of the architects, Studio E, to follow the guidance in the document.
The first phase of the inquiry concluded that Grenfell Tower breached the headline building regulation that requires external walls to “adequately resist the spread of flame”. Approved Document B is intended to be the official guidance on how to meet that standard.
However, the correct interpretation of the guidance on cladding panels remains crucial in unpicking the cladding crisis currently gripping the country, with many problematic systems also utilising cladding certified to a Class 0 standard.
Today, Mr Hyett gave a presentation to the inquiry where he built up a 3D model of the cladding system as designed by Studio E.
This illustrated known flaws such as cavity barriers placed at the lines between flats rather than above windows, the use of combustible insulation and the large gap created by moving the new windows forward.
Mr Hyett also demonstrated a way to have built up the system using non-combustible insulation and correctly positioned barriers which would have achieved a similar aesthetic appearance, albeit with a thicker wall.
Before he gave evidence, chair Sir Martin Moore-Bick confirmed it will continue when the country enters its second lockdown period on Thursday.
He said that as the inquiry is a workplace with “robust measures” in place to ensure safety, it is able to continue its operations under the rules. Although he added that this may need to be reconsidered if the situation changes.
In March, the inquiry was put on hold for more than 10 weeks due to lockdown and the need to adapt the venue for socially distanced hearings.
The Grenfell Tower Inquiry continues.
Week one: A vivid picture of a broken industry
After a week of damning revelations at the opening of phase two of the Grenfell Tower Inquiry, Peter Apps recaps the key points
Week two: What is the significance of the immunity application?
Sir Martin Moore-Bick has written to the attorney general requesting protection for those set to give evidence at the Grenfell Tower Inquiry. Peter Apps explains what the move means
Week three: Architects of misfortune
This week saw the lead architects for the Grenfell Tower refurbishment give evidence to the inquiry. Peter Apps runs through the key points
Week four: ‘I didn’t have any perception that it was the monster it’s become’
The architects continued to give evidence this week, outlining a lack of understanding of the fire risk posed by the cladding materials and its design. Nathaniel Barker reports
Week five: ‘No adverse effect in relation to external fire spread’
As the Grenfell Tower Inquiry returns from its long absence, Peter Apps recaps the key points from a week of important evidence from the fire consultants to the refurbishment
Week six: ‘I can’t recall any instance where I discussed the materials with building control’
Nathaniel Barker summarises what we learned from fire engineers Exova, architects Studio E and the early evidence from contractor Rydon
Week seven: ‘I do not think I have ever worked with a contractor operating with this level of nonchalance’
Two key witnesses from contractor Rydon gave evidence this week. Peter Apps recaps some of the key points from a revealing week of evidence
Week eight: ‘It haunts me that it wasn't challenged’
Four witnesses from contractor Rydon gave evidence this week. Lucie Heath recaps what we learned on the last week of evidence before the inquiry breaks for five weeks
Week nine: ‘All I can say is you will be taken out for a very nice meal very soon’
This week the inquiry heard evidence from witnesses at Harley Facades, the sub-contractor responsible for Grenfell Tower’s cladding. Peter Apps recaps the key points
Week 10: ‘As we all know, ACM will be gone rather quickly in a fire!’
As the Grenfell Tower Inquiry entered its 10th week, Jack Simpson recaps the key points from a week of important evidence from the refurbishment’s cladding contractor
Week 11: ‘Did you get the impression Grenfell Tower was a guinea pig for this insulation?’
With witnesses from the cladding subcontractor, the firm which cut the deadly panels to shape and the clerk of works which inspected the job giving evidence this was week full of revelations. Peter Apps recaps the key points
Week 12: ‘Would you accept that was a serious failing on your part?’
With the surveyor who inspected Grenfell Tower for compliance giving evidence, this was a crucial week from the inquiry. Dominic Brady and Peter Apps report
Week 13: ‘Value for money is to be regarded as the key driver for this project’
With consultants to Kensington & Chelsea Tenant Management Organisation (KCTMO) giving evidence, attention at the Grenfell Tower Inquiry turned for this first time to the actions of the TMO and the council. Peter Apps reports
Week 14: ‘Did it not occur to you at this point that your budget was simply too low?’
This week, for the first time in phase two, the inquiry heard from Kensington & Chelsea Tenant Management Organisation, the landlord that oversaw the fatal refurbishment of Grenfell Tower. Lucie Heath reports
Week 15: ‘Have you ever informed the police that you destroyed documents relevant to their investigation?’
Witnesses from the Kensington and Chelsea Tenant Management Organisation (KCTMO) gave evidence for a second week, which began with a shocking revelation about withheld and destroyed evidence. Pete Apps recaps
Week 16: ‘I conclude this was very serious evidence of professional negligence’
This week saw members of Kensington & Chelsea Tenant Management Organisation finish giving evidence, before the inquiry’s expert witnesses took the stand to make some highly critical assessments of the work they had seen before and during the refurbishment of Grenfell Tower. Jack Simpson recaps
Week 17: ‘It’s hard to make a note about this because we are not clean’
The start of the second module of the Grenfell Tower Inquiry phase two came with some huge revelations about the companies that sold the products used in the cladding system. Peter Apps reports
Week 18: ‘It was just reckless optimism wasn't it?’
As the inquiry began cross-examining witnesses for the second module of its phase two work, the picture surrounding just how Grenfell Tower ended up wrapped in such dangerous materials became a little clearer. Nathaniel Barker was keeping an eye on proceedings
Week 19: ‘And that was intentional, deliberate, dishonest?’
The Grenfell Tower Inquiry this week heard the shocking story of how the insulation manufacturer "manipulated" official testing and marketed its product "dishonestly". Peter Apps tells the story
Week 20: ‘We were outed by a consultant who we then had to fabricate a story to’
This week the inquiry investigated the actions of Kingspan – the manufacturer of one of the insulation products used in the tower’s cladding system. Dominic Brady reports
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