The Grenfell Inquiry will present its conclusions next Wednesday more than seven years after the fire. Here鈥檚 a summary of the evidence the inquiry chairman Sir Martin Moore-Bick has had to unpick

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The scene outside the tower in the weeks after the fire

It has been seven years, one month and 27 days since the UK construction industry was changed forever by the fire at Grenfell Tower. That tragedy, which claimed the lives of 72 people, was quickly recognised at the time as a watershed in how we design and construct tall buildings. 

Since then, a new building safety regulator has been created, new rules rolled out to reduce the risk posed by fires, and the way the industry operates has been irreversibly changed. But we still do not know the definitive answer to the question: how did 3,000 sq m of highly combustible cladding panels end up being installed on a 24-storey residential tower?

On Wednesday we will finally get some answers in the form of the final report from the Grenfell Inquiry. Ordered the day after the 14 June 2017 blaze by then prime minister Theresa May, the inquiry has been split into two phases overseen by chairman Sir Martin Moore-Bick. The first, looking into the events on the night of the fire, was followed by a report published in 2019. The second phase, which will be the subject of next week鈥檚 report, assessed the causes of the disaster and the role of construction firms, product manufacturers and government policy. 

>> See also: Grenfell Tower Inquiry鈥檚 final report to be published on 4 September

>> 鈥榃e must be honest with ourselves鈥: Mace boss says industry needs further improvement as firms brace for Grenfell Inquiry report

Much of the evidence heard during this phase has been shocking and is well known, but to remind readers of the key findings ahead of the report, here is a summary of what to look out for.

Government inaction

The inquiry heard evidence that the construction industry should take some, but by no means all, of the blame for the tower鈥檚 flawed refurbishment. Three elements contributed: sloppy design and construction work, misleading marketing of cladding products, and the government鈥檚 failure to recognise the risk of ACM.

Evidence from government officials and ministers highlighted how a policy of deregulation was adopted by the coalition government under David Cameron in the years before the fire which was intended to stimulate the economy in the wake of the 2008 financial crisis. 

In 2011, the Cabinet Office introduced a 鈥渙ne in, one out鈥 policy which restricted departments to only adding new regulations if they removed existing ones. This was strengthened to 鈥渙ne in, two out鈥, in 2013 and 鈥渙ne in, three out鈥 in 2016. This complicated the job of amending regulations as officials needed to balance any additions by choosing which rules they should cut.

At the time, officials were attempting to amend building regulations following the 2009 Lakanal House fire, which was caused by combustible cladding panels similar to the ones used on the later refurbishment of Grenfell Tower. These amendments were never made despite a series of warnings from worried industry experts, including several letters sent by the London Fire Brigade to the housing department in the months leading up to the fire.

Because of the government鈥檚 deregulation policy, relatively straightforward plans to clarify the risk of external fire spread in the wake of Lakanal had been expanded into a wider review of the entire 300-page Approved Document B, the part of building regulations that deals with fire safety. It was then expanded further to encompass a wider review of building regulations, a process which would take years.

Grenfell montage

Clockwise from top left: Bob Ledsome, senior civil servant at the then DCLG (now the DLUHC); Eric Pickles, secretary of state for housing 2010-15, now Lord Pickles; Gavin Barwell, housing minister 2016-17 before losing his seat, now Lord Barwell; Brian Martin, civil servant to whom everyone at the DCLG would turn for fire safety advice; Brandon Lewis, housing minister 2014-16; Stephen Williams, Liberal Democrat communities minister at the DCLG, 2013-15

Ministers claimed to have been 鈥渃omforted鈥 by officials in charge of the regulations that the situation was not 鈥渓ife safety critical鈥 but there was also considerable confusion and miscommunication between those involved. Pickles, who led the housing department between 2010 and 2015, said he believed fire safety was exempt from the deregulation drive, yet officials were under the impression that it was not and had not spoken up because they considered it a 鈥渇ight not worth having鈥 in a policy environment where regulation was seen as a 鈥渄irty word鈥.

Brian Martin, the civil servant in charge of building regulations for nearly 18 years before the Grenfell fire, was also dealing with confusion in the industry over a term in the regulations which appeared to permit combustible cladding panels in high rise buildings. A passage under the heading 鈥淚nsulation Materials/Products鈥 stated that the tough fire standard of 鈥渓imited combustibility鈥 only applied to 鈥渇iller鈥 materials. 

Despite the heading, Martin claimed at the inquiry that this also applied to the core of cladding panels such as ACM, the type used on Grenfell Tower. But he never clarified this before the fire, despite being warned of the confusion by a group of industry experts, telling the inquiry that he 鈥減robably forgot about it鈥 as it had been a 鈥渂usy time鈥.

Martin and other departmental officials were also aware of a disastrous fire test on ACM carried out in 2001. Despite receiving the Class 0 rating which permitted its use on tall buildings, the cladding product had burned with such ferocity that after just five minutes the flames reached 65ft high - twice the height of the test rig - and had to be extinguished due to safety concerns. Martin said the test had 鈥渏ust been forgotten鈥.

Despite this test, 16 years before Grenfell, and several widely reported cladding fires in the Middle East during that time, Martin told the inquiry that he had 鈥渃ompletely underestimated the hazard鈥 of ACM and had not raised the confusion over the word 鈥渇iller鈥 with any other senior official at the time.

Flawed product testing and marketing

Some of the above might suggest that the industry was defensibly acting within the regulatory environment before the fire. But a series of shocking disclosures from product manufacturers revealed how far some firms went to ensure cladding materials that they knew were unsafe could be sold on the market.

Hearings were told how Celotex, which manufactured most of the insulation installed behind the ACM panels, had rebranded the product after it had failed a fire test and then rigged a second test to ensure it would pass. Fire resistant boards had been surreptitiously added to the rig, apparently unnoticed by testing staff, to reduce the spread of flame.

A burn hall manager questioned by the inquiry said the reliance during tests was 鈥渧ery much on the honesty of the client鈥 and that there was a 鈥渓arge element of trust in everything we do鈥. He denied being aware that Celotex had added the fire resistant boards, blaming the oversight on the burn hall being a 鈥渂usy place鈥.

Grenfell Tower one week after the fire

Source: PA Images

Grenfell Tower one week after the fire

Celotex was said to have rigged the test after the firm鈥檚 owner Saint Gobain had given it a 15% profit increase target aiming to achieve a lucrative sale of the business. Jonathan Roper, a 23-year-old product manager who was given the job of developing the 鈥渘ew鈥 product despite having no technical experience or training in building regulations, described Celotex鈥檚 actions as a 鈥渇raud on the market鈥 and 鈥渃ompletely unethical鈥.

Meanwhile, Arconic, which supplied the ACM panels that were found to be the primary cause of the fire at Grenfell Tower, had been selling the product using the test report from a different, less combustible version of the panels. When a fire test was conducted on the version used on Grenfell it failed 鈥渄isastrously鈥, but this was never passed on to the British Board of Agr茅ment (BBA), a certification body, which then issued certificates allowing the product to be used on high rise buildings. Arconic鈥檚 president denied that this had been 鈥渄eliberate concealment鈥, insisting that the BBA 鈥渃ould have found out鈥 about the failed test in an audit.

The inquiry also heard how Arconic had been selling the panels for 10 years despite being warned of the fire risks. A sales manager admitted in a secretly recorded phone call that the product had not been taken off the market because of 鈥渃ost implications鈥.

>> See also: Kingspan, Celotex and Arconic settle civil claims with 900 people affected by Grenfell fire

Investigators had also found a small amount of Kingspan鈥檚 popular K15 insulation had been used in the cladding system for the refurbishment. In 2020, prior to the start of hearings, Kingspan had admitted that it had been marketing this product for 15 years using the test report of an older, chemically different version of the product. When the new variant had been tested in 2007, within 17 minutes it had turned the rig into a 鈥渞aging inferno鈥 which had to be extinguished over fears that it would set fire to the laboratory.

But despite the firm stating in its letter to the inquiry that it was 鈥渘ow of the view鈥 that there were differences between the product that was tested and what had been sold on the market, a former technical project manager claimed this had been 鈥渃ommon knowledge鈥 at the firm since the product was altered.

Sloppy construction work

Adding to a confusing regulatory environment and misleading marketing of combustible cladding products was an array of shortcomings made by the project team which carried out the refurbishment.

Rydon was appointed main contractor by project client Kensington and Chelsea Tenant Management Organisation (KCTMO) in March 2014 on a 拢9.2m bid, the lowest out of four bidders. This came after a secret meeting that year between Rydon and KCTMO which had agreed to trim another 拢800,000 off the cost of the job.

The team, which included architect Studio E and facade engineer Harley, then set about choosing the products for the scheme. After considering zinc cladding, Arconic鈥檚 ACM panels were chosen in a value-engineering move to minimise costs and Celotex鈥檚 insulation panels were selected because of their thinness and 鈥渁spirational鈥 thermal efficiency targets. The fire performance of the products was never properly scrutinised by any team members.

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Grenfell tower, surrounded by nearby tower blocks

Harley was said to have lost technical expertise through staff changes and for a three year period did not employ anyone qualified to check the fire performance of specified materials. The firm had appointed the 25-year-old son of company boss Ray Bailey as project manager for the job after struggling to assemble a team. Expert witness Paul Hyett said the firm 鈥渃learly did not understand鈥 the requirements of the 好色先生TV Regulations and produced 鈥渇undamentally flawed鈥 detailed design work.

Hyett also said Rydon missed several 鈥渟erious omissions and errors鈥 in drawings produced by Studio E and its subcontractors, and had failed to establish a proper matrix of responsibilities between project team members. This became a crucial problem, allowing Studio E, which had no experience of working on high rise buildings, to shirk some its responsibilities, according to Hyett, who described the way in which the team supplied documents to building control as a 鈥渟hambles鈥.

Rydon had also chosen not to hire fire consultant Exova as a full member of the project team. The firm, which continued to work on the scheme on ad ad hoc basis, has said it was excluded from the team.

This was rejected by another expert witness, Arup director Barbara Lane, who said Exova鈥檚 advice on fire safety had been 鈥渆ntirely inadequate鈥. The firm had said in a key document that the proposed works on the tower would have 鈥渘o adverse effect鈥 on external fire spread, despite having failed to analyse the designs or the cladding system. 

Cavity barriers within the cladding system, designed to slow the spread of fire, were also found to have been either missing or so badly installed that they were ineffective. Two cladding fitters who had worked for Harley admitted to the inquiry that the quality of some of the firm鈥檚 work was 鈥渟hocking鈥 and 鈥渦nacceptable鈥.