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Grenfell Tower Inquiry diary week 64: ‘I didn’t think ACM would be suitable for use in any high-rise buildings. I don’t think anyone did’

Insight18.02.223.30 PM by Jack Simpson

This week, the Building Research Establishment’s Dr Sarah Colwell gave more than three days of evidence, with some huge revelations about what was known about the dangers of aluminium composite material (ACM) years before the fire and the mass confusion over the government’s building regulations. Peter Apps and Jack Simpson report

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This week the BRE’s Dr Sarah Colwell gave more than three days of evidence, with some huge revelations about what was known about the dangers of ACM years before the Grenfell fire #UKhousing

What is Class 0?

It is necessary to begin with a quick explanation of a fire standard which was at the heart of much of this week’s evidence: Class 0. Technically, this standard is achieved by a material which passes two tests set out in a British Standard.

There have long been concerns about how reliable it is. In brief terms, the tests primarily assess the performance of the surface of a material, and some highly combustible products can obtain it.

Building regulations guidance for England and Wales, contained in the government publication Approved Document B, said that “external wall surfaces” of tall buildings needed to meet this standard. This was taken to mean that cladding panels with this classification were acceptable under our rules.

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This week we heard how, for 30 years before the Grenfell fire, warnings that this standard was too low and risked disaster were repeatedly missed.

‘Can we agree that the clear inference of that paragraph is that this was a non-combustible system?’

The story began with a fire in 1991 at a block in Knowsley Heights, Merseyside.

This fire has long been talked about as a staging post in the story of the cladding crisis in the UK. We explored it in detail here.

The building was a pilot scheme, funded by the government to test the efficacy of cladding as a means to insulate council tower blocks. It was being monitored by the government and the Building Research Establishment (BRE), the testing and research facility that was part of the British state until it was privatised in 1997.

The fire, which had ripped up all 10 floors of Knowsley Heights and was affecting the roof by the time the fire service arrived, could have been a major alarm bell of the potential for disaster associated with cladding.

It was not, and our previous investigation revealed a handwritten note suggesting a desire to “play down” the fire.

This week, the inquiry considered something different: the combustibility of the materials on the tower.

Many in the industry understood Knowsley to have been clad with non-combustible materials. They believed the blaze spread because of the unprotected cavity between the external cladding panels and the insulation. Indeed, a new requirement to put barriers into this cavity was the only regulatory change following the fire.

The BRE’s report into the fire, revealed by the inquiry this week, showed that the cladding panels were glass reinforced plastic (GRP). They possessed a Class 0 rating and were combustible.

But the BRE’s report made no significant issue of this. In fact, it said a few paragraphs later that cavity barriers were not fitted and noted that “under [official] guidance at the time [cavity barriers] could be omitted where the cladding system was non-combustible”.

“Can we agree that the clear inference of that paragraph is that this was a non-combustible system, otherwise why would that sentence read as it does at the end?” asked Kate Grange QC.

“I’m sorry, I can’t speak for what the authors were suggesting with that,” replied Dr Colwell.

The same description was used in a summary report of major cladding fires, produced by the BRE in 2016, which Dr Colwell was listed as having signed off. She explained this by saying it simply followed the original report, but did not endorse it.

The 2016 report listed several potential factors for the rapid spread, but omitted any mention of the combustible cladding.

Asked if she felt the panels should have been added to the list of factors which “caused the fire to propagate from the base of the tower to the roof within minutes”, Dr Colwell said: “Given that GRP was combustible, it could have been highlighted, yes.”

‘It is clear… that a cladding material achieving a Class 0 rating may suffer extensive surface burning’

Following the Knowsley Heights fire, the BRE began to work on a large-scale cladding test which would ultimately become the BS-8414 system test the inquiry has heard so much evidence about in the past.

This research involved running a series of large-scale tests at its research facility in Cardington.

This research plainly identified the problem with Class 0 cladding. The report prepared by Dr Raymond Connolly said: “It is clear… that a cladding material achieving a Class 0 rating may suffer extensive surface burning. This burning often spread to the top of the test building (some 9 metres) and would have spread further if possible.”

“In the light of this report, did you at any stage consider the reliance in Approved Document B … on [Class 0] to be a matter that needed to be addressed?” asked Ms Grange.

“Yes,” Dr Colwell replied. “The pick-up from what I was being told and had been explained to me suggested that that was what was going to be addressed, because they had found evidence that it wasn’t appropriate.”

But a further opportunity to make this point came and went. In 1999, there was a fire at Garnock Court in Irvine, Scotland. This blaze also spread through glass reinforced plastic panels to the top of the block. The BRE was commissioned to report on it for both the government and North Ayrshire Council, which owned the tower.

The report to government was clear that the blaze was a consequence of the panels. “The plume will have ignited the GRP and remained in contact with it and generated a self-propagating fire,” it said.

But it contained no reference to the fact that these panels were supposed to be Class 0.

“Did you notice that the report was silent on whether or not the panels had achieved national Class 0?” asked Ms Grange. Dr Colwell said she couldn’t explain it.

What is particularly odd is that the report to North Ayrshire Council did make numerous references to the Class 0 categorisation, noting that it was unlikely the panels would have achieved it.

In fact, when the reports were shown side-by-side, it was clear that exactly the same wording was frequently used in both, with the paragraphs on Class 0 simply deleted in the report to government.

“Were you aware at the time that the department was keen to play down any references to concerns about national Class 0 or the deficiencies in national Class 0? Was that something you were aware of at this time?” asked Ms Grange.

“No, not at all,” said Dr Colwell.

Dr Debbie Smith, former managing director of the BRE, (pictured above) was also asked about this report. She said the “only possibility might be that more information became available” if the reports were done at different times. But she added that she was “speculating”.

In opening statements, lawyers for the bereaved and survivors were damning about these two reports, which they said were “consistent with government legitimising the flammability of the cladding”.

One of the BRE’s authors of the report to North Ayrshire was a man called Brian Martin. He would ultimately leave the BRE to take over responsibility for the official guidance within government.

‘Did you consider after this test that the use of ACM panels on a high-rise building would present nothing other than a grave risk to occupants?’

Following Garnock Court, the government commissioned the BRE to run 14 tests on cladding systems to road test its new methodology for cladding-system tests.

These tests ran in 2001, and appear to represent a breathtaking missed opportunity to prevent the Grenfell Tower tragedy.

This is because, included in the testing, was the polyethylene-cored aluminium composite material (ACM) that would later be used on Grenfell Tower.

Of the 14 systems tested, 10 failed – the ACM the most dramatically. A table of results revealed that it took only three minutes for the fire to penetrate the whole of the exterior part of the ACM PE cladding system, with flames entering the external insulation within four and half minutes. This was half the time it took the next-worst performing material.

A timeline of the test was even more harrowing.

The note described molten aluminium dropping off the front face of the ACM system after just three minutes and flames reaching 20m high after just five minutes. The test had to be fully extinguished for safety reasons after just seven minutes. It would be described by Ms Grange as a “catastrophic escalation of fire”.

In her evidence, Dr Colwell, who witnessed the tests, said she was “shocked” by the speed with which the fire took hold, adding that government officials were also “concerned about the performance”.

She was clear at that point that ACM shouldn’t be used on high-rises. Asked if she was of the opinion “after this test that the use of ACM panels on a high-rise building would present nothing other than a grave risk to occupants”, she replied: “Yes, I couldn’t see that ACM would be an appropriate product for use in that application.”

The ACM used in this test was rated Class 0.

“Did these results suggest to you in very clear terms that it would be seriously irresponsible for anyone to continue to allow Class 0 to be used as a standard for assessing the fire performance on high-rise buildings?" asked Ms Grange.

Dr Colwell agreed. But why not tell the government to remove the standard immediately?

“In the conclusions to this report we made clear that there was a difference that needed to be addressed, and on that basis and the evidence provided, my understanding was that they would review the guidance accordingly,” she said.

Did she check to see if it was followed up? “I wasn’t aware that they [the government] hadn’t [taken any action] at the time, but I’m still shocked that it is and was used,” she said. “So yes, on reflection, I’m shocked they didn’t follow it up at that point.”

‘Any insulation product or any other material used in external wall construction should be of limited combustibility’

In January 2005, there was a serious fire at The Edge building in Manchester.

The fire at the 19-storey block started on a balcony. It quickly spread to the cladding panels, made up of two sheets of aluminium with an expanded polystyrene core. Within 10 minutes, the fire had spread up 17 floors.

Investigations were launched into the fire, with Dr Colwell and the BRE publishing a report to the government which found that the polystyrene core of the sandwich panels used on the walls was not exposed to the internal cavity.

The wording of Approved Document B suggested limited combustibility insulation was only required in “ventilated cavities”, meaning designers may have taken the view that the restriction was not applicable elsewhere.

Dr Colwell’s report called for the passage in Approved Document B to be made more explicit, with the government told of “grave concerns” in the fire and rescue services if buildings like this were occupied in the future.

Mr Martin, by then the chief civil servant responsible for the guidance, agreed that the guidance needed clarification and redrafted the passage to make it clear that “any insulation product or any other material used in external wall construction should be of limited combustibility” (emphasis added).

This would have blocked the use of not only combustible insulation, but combustible cladding panels as well. But it was not what went into the final version.

Instead, below a heading reading ‘insulation’, the new paragraph 12.7 said: “In a building with a storey of 18m or more any insulation product, filler material used in external wall construction should be of limited combustibility”.

This appeared to imply only insulation materials were covered by the requirement for limited combustibility, with cladding still subject to the weaker Class 0 standard, which was never removed from the guidance.

Asked if she felt that the wording that was used in the actual revision was a lot less clear than that used in the initial draft, Dr Colwell agreed.

This issue would raise its head again in the 2010s, and once more the opportunity to provide clarity would be missed.

‘That is something that I, with reflection and hindsight, regret’

This 2001 test was not the only knowledge Dr Colwell had of ACM fires pre-Grenfell.

In her witness statement she admitted that, by July 2014, she was aware of a number of ACM fires that took place in the Middle East. After high-profile ACM fires at Al Hafeet Tower in April 2013 and the Al Tayer Tower in April 2012, both in Sharjah, the United Arab Emirates government brought together a task force to rewrite fire safety codes. Dr Colwell spent two years as part of that team.

Again, despite having intimate knowledge of just how disastrous the presence of ACM could be on high-rise buildings, she didn’t make big efforts to alert those back in the UK.

“I believed that the requirements of [Approved Document B] were actually there to prevent it being there and I didn’t look beyond that,” she said. “That is something that I, with reflection and hindsight, regret.”

When asked why the BRE didn’t go out to industry to warn them about the dangers of ACM itself, given what was known about the lack of clarity around approved document B, Dr Colwell said: “In general terms, at that time, those would be referred back to the department to address, we wouldn’t step into that space.”

“Even if there was a life safety risk?” asked Ms Grange.

“The vehicle and authority for those type of statements were expected to come from the department,” Dr Colwell replied.

‘It’s wholly misleading, isn’t it?’

In July 2014, Dr Colwell was invited to an industry summit to discuss precisely this risk – an issue which the inquiry investigated with another attendee at the meeting last week.

At the meeting, concerns were raised specifically around the use of ACM and Dr Colwell explained her view that use of the product was banned by paragraph 12.7 of Approved Document B, which required the use of “limited combustibility” insulation.

This was a standard polyethylene-cored ACM could not achieve, but there was a problem. ACM is not insulation. Many in the industry believed the appropriate standard remained Class 0 – which the guidance still said was the requirement for “external wall surfaces”. As a result, ACM was in wide use.

Dr Colwell agreed, as a result, to draft a frequently asked question (FAQ) to clarify that ACM should not be used. She would present this to the senior official, Mr Martin, who would publish it on a government website.

However, the FAQ never came to be.

Dr Colwell told the inquiry that, by September 2014, she and the BRE had made the decision that she would not be pushing forward with the FAQ route, instead deciding that the issue would be dealt with in a forthcoming revision of Approved Document B.

But she failed to tell anyone else who had attended the meeting of this change of plan. Instead, she implied the opposite.

In September 2014, she had a meeting with industry representatives about the issue. Minutes note that the BRE would “prepare words for Approved Document B portal 12.7 clarification”. This was after she had decided not to do so.

Asked by Sir Martin Moore-Bick (pictured above), the chairman of the inquiry, if this gave the impression to members that she was still drafting the FAQ, she said she regretted not being as “open as she should have been” about her decision.

The inquiry was shown images of a presentation at an industry event which indicated the BRE was pulling the FAQ together.

And in March 2015 when David Metcalfe, director of the Centre for Window and Cladding Technology (CWCT), emailed to ask for an update on the FAQ, Dr Colwell replied that the note had been drafted and it would be “hopefully closed soon” and then “circulated”.

“It’s wholly misleading, isn’t it?” asked Ms Grange.

“With hindsight, yes, it is,” replied Ms Colwell.

Mr Metcalfe sent four follow-up emails in August, October and November, none of which received a response.

Dr Colwell said her lack of transparency with the CWCT was a big regret. Asked at the end of her evidence what she would change about her actions, she said: “The period of reflection with CWCT activities from 2013; I absolutely would have handled that a different way.”

‘A buck-passing load of incompetents’

In January 2016, Nick Jenkins, then at Euroclad, the cladding supplier, sent a lengthy email to her about the proliferation of ACM PE in tall buildings across England.

He explained that he was aware these “panels burned efficiently” and were being installed on a number of new buildings alongside combustible insulation.

The company wanted to send a warning note to its clients and was seeking clarity from the BRE on this.

Yet Mr Jenkins didn’t get an immediate reply. After the first email, he sent two chasers. Dr Colwell eventually replied, saying she would check and come back to him. After a further seven days, Dr Colwell replied by simply telling Mr Jenkins to email Mr Martin.

Exasperated by the response, Mr Jenkins sent it to his manager, Euroclad managing director Phil Cook. Mr Cook responded by describing the BRE as “a buck-passing load of incompetents”.

During questioning, Dr Colwell disagreed with this description, saying the government were the people able to provide the definitive guidance.

Mr Jenkins did forward the email to Mr Martin.

The civil servant responded by stating that the core of an ACM panel “could be considered filler”. This, he argued, brought it within the scope of paragraph 12.7, which referred to “filler materials etc” as well as insulation, meaning it was required to meet the tougher fire standard of limited combustibility or pass a large-scale test.

He added: “If the designer and building control choose to do something else, that’s up to them.”

A follow-up email from Mr Jenkins stressed to Mr Martin that there had been no large-scale tests on ACM PE products and that the number of buildings containing these materials were “many” and “growing”. He called for a meeting to address the issue.

Mr Martin agreed that a meeting was a good plan and that he would be “happy to help where he could”. He also said: “Constructions complying with rule of thumb may well fail [a large-scale test]... In an ideal world we’d make the test mandatory, but that would be too costly to justify.”

When asked by Ms Grange (pictured above) if she was surprised that Mr Martin couldn’t give a definitive answer, Dr Colwell said that it was “very much in the style of Brian’s responses”.

“I was used to seeing that style of response, so I didn’t read too much into it at the time,” she added.

Quizzed on why she didn’t do anything after Mr Jenkins’ warning, she once again pointed to the fact that she had made the government aware of this and they were in the best position to alert the industry.

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