Grenfell Tower - How did it happen?

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The Grenfell Tower tragedy has horrified everyone. The stories – stories of people trapped and dying in full view of their neighbours — are unbearable to hear. But the construction industry has to hear them. It has to be haunted by them. Because a building has failed, catastrophically, and 80 people are dead.

In the weeks that have passed since that awful night, a police investigation has been launched, as has a public inquiry under retired judge Sir Martin Moore-Bick. The government has also appointed an expert panel under Sir Ken Knight to give immediate advice, and has announced a formal review of the building regulations under Dame Judith Hackitt.

But the immediate and specific reason for the terrifying intensity of the blaze seems to have been the use of a combustible cladding system in the refurbishment of the building, which was carried out just a year ago. Watching video footage of cladding flaring up and pouring off in flames, it is hard to come to any other conclusion.

Inside the building, a series of additional factors potentially made things even more dangerous for the residents. It’s possible that internal fire breaks and compartmentation were compromised during the refurbishment, perhaps after the new heating system was installed.

Surprisingly to many, the tower retained its gas supply, including individual supplies to each flat. Risers and pipes in landings and stairways were supposed to be clad in “fire-rated” boxing, but contractor Cadent Gas has reportedly said that “work was still ongoing to box in the lateral pipes” when the fire occurred. The London Fire Brigade was reported as saying that it had been unable to put out the fire – which started when a refrigerator caught fire in a fourth floor flat – until fire fighters had isolated a ruptured gas main.

Smoke protection or extraction systems in the stairwell appear to have either been unable to deal with the quantity of smoke, or to have failed. Certainly, a number of the injuries and fatalities were caused by smoke inhalation when occupants were attempting to get down the stairs.

These issues relate not only to the refurbishment – its design and execution – but also to the ongoing management of the block. At the time of writing, the Royal Borough of Kensington and Chelsea, and the Kensington and Chelsea Tenant Management Organisation are both being investigated for possible corporate manslaughter.

But the initial focus has been on the cladding system. Important questions remain about the integrity of the firestopping, and whether the nature of the assembly created a chimney effect that accelerated the blaze.

But we now know, after tests carried out for the government by the BRE, that the system used at Grenfell Tower has failed the tests set out in Approved Document B of the building regulations. It is flammable. It should never have been installed on the building.

Just weeks before the Grenfell disaster, the insurance industry warned the government of the dangers of flammable cladding on buildings.

The outer rainscreen cladding at Grenfell Tower was a Reynobond PE composite panel made of an unmodified polyethylene core sandwiched between two layers of aluminium.

This was set about 50mm away from the insulation that was fixed against the rough concrete walls of the 40-year-old structure.

For the most part the insulation was Celotex RS5000, but the vertical columns and corners were insulated with Kingspan Kooltherm K15 – and Kingspan has stated that this use of the product was “as part of a combination for which it was not designed and which Kingspan would never recommend.”

Both these synthetic foam insulants are combustible at high temperatures. In the test at the BRE – which tested foil-backed PIR insulation with stone wool fire barriers behind a polyethylene- filled aluminium composite material (ACM) rainscreen cladding – it took just nine minutes for the flames to reach several metres up from the top of the six metre high mock-up cladding system – just nine minutes to establish the cladding system should not have been on that building. How, then, did it come to be there?

While the deeper, cultural answers to this question are difficult to pinpoint with accuracy, the reasons appear to be wrapped up in the culture of deregulation and cost-cutting that has gripped both the construction industry and government over the past decade.

Particularly since the Conservatives came to power in 2010, but stretching well back into the Blair years, successive governments have prioritised deregulation as part of a “war on red tape”.

In January 2012, the then prime minister David Cameron said he intended to take “concrete steps to make it easier for businesses to cope with the great big machine of health and safety that’s built up... the health and safety monster.” It was one of many similar statements he and his government made.

This culture of deregulation also extended into construction. When a housing standards review was announced in 2012, the government’s guiding principles included its desire for a “proportionate” role for regulation, which “mustn’t stifle growth or innovation”.

And fire safety was not spared the deregulatory credo, despite repeated pleas and warnings that the fire safety regime was a danger to human life.

According to the BBC, after a fire at the Lakanal House tower block in south London killed six people in 2009, the all-party parliamentary fire safety and rescue group petitioned government ministers to reform Part B of the building regulations, which deals with fire, by including provision for automatic sprinklers and revisiting fire standards for cladding.

Lakanal house Photo: Peter Gasston

Despite this advice, rules to mandate sprinklers were not introduced, apparently as they might have discouraged house building. While former housing minister Brandon Lewis accepted that automatic sprinklers save lives, he stated that it was not the government’s responsibility to make them mandatory. “It is for the fire industry, rather than the government, to market fire sprinkler systems effectively and to encourage their wider installation,” he said, citing the government “one-in, two-out rule” on new regulations.

Civil servants echoed the deregulation dogma of the time. According to the New York Times, Brian Martin, the top civil servant in charge of drafting building-safety guidelines, said at a conference in 2011: “If you think more fire protection would be good for UK business, then you should be making the case to the business community, not the government.”

He reportedly quoted the then fire minister, Bob Neill, as saying: “Should we be looking to regulate further? ‘No’ would be my answer.”

The New York Times also reported that, two years later, when the coroner questioned Brian Martin about the Lakanal House fire in London, he defended the building regulations.

When it was put to him that the public would be horrified to learn that the rules allow the use of combustible panelling, Martin reportedly said: “I can’t predict what the public would think, but that is the situation.”

He also said that demanding the use of non-combustible cladding materials “limits your choice of materials quite significantly”.

A visceral dislike of regulation seemed to grip members of government. Retired architect Sam Webb, who sits on the all-party fire and rescue group, recalls: “I sat in one meeting where we discussed the need for the retro-fitting of sprinklers during the refurbishment of multi-storey blocks of flats.”

“As [former chief fire officer] Ronnie King patiently outlined the reasons, the then minister for DCLG [Department of Communities & Local Government] pointed his finger and shouted, ‘Mr King you are in a minority of one’. When we interjected, the minister leapt to his feet, threw his papers down and stormed out of the room, shouting as he went that he was resigning from the group.”

Sadly, there had been no shortage of hard evidence about the danger of combustible cladding systems. In Shanghai in 2010, a 28-storey apartment building, which was under renovation, was consumed by fire. Fifty-eight people were killed and 70 were hospitalised. It is believed that the fire spread via polyurethane insulation on the external walls.

A series of dreadful fires in the United Arab Emirates also caused tremendous damage and a number of injuries, though mercifully no loss of life: measures such as sprinkler systems, effective compartmentation and safe escape routes are believed to have saved lives. As a result of the UAE fires, combustible cladding materials were banned in the country and new regulations covering construction practice and quality control are in the process of being introduced.

There have been similar fires closer to home. A fire in a tower block in Irvine, North Ayrshire killed one person and injured five more in 1999. The fire spread up the outside of the building via combustible cladding.

Ten years later, the fire at Lakanal House also spread via external cladding.

The Fire Sector Federation has had a long-running campaign for a review of Approved Document B to the building regulations, and recently produced a brochure titled ‘Why does Approved Document B need to be reviewed?’ Approved Document B provides technical guidance on how to meet Part B.

Tom Roche, chair of the FSF’s built environment workstream, warned: “Increasingly, as a Federation we are noting combustible combinations in terms of construction systems and insulation products within building assemblies. This is evident in the scale of fires that we are witnessing, in the UK and abroad.”

“As a federation our concern has been that these changes are outrunning the current testing regimes in the UK, that the testing of individual components and not systems gives a misleading picture of their true fire performance.”

The website Safety and Health Practioner reports that at the FIREX International convention, coincidentally held just a few days after the Grenfell disaster, Dennis Davis of the Fire Safety Federation said his industry had warned about the building regulations “time and time and time again”.

“We are desperately worried, in particular the approved documents falling behind what is going on within the built environment,” he told delegates. “We must get over this. 2006 [sic] is the last review. Ten years is too long a gap, far too long a gap if you consider how much construction and building has changed.”

This brings us to the desperate situation at Grenfell Tower on the night of 14 June. The building’s external cladding system, which lit up like a match, may even turn out to have been compliant with Part B — or at least, legalistically speaking, compliant with one of the four different ways that building control bodies have suggested the regulation can be interpreted.

Why don’t we know for sure? Because Part B –and the manner in which it is interpreted by building control bodies — is dangerously confusing.

In relation to external fire spread, Part B itself simply states: “the external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building.” (It makes an almost identical statement for roofing).

The word ‘adequately’ is discussed in some detail, but what it means in essence is that the building should be very hard to set on fire from the outside.

The official technical guidance (Approved Document B) offers two ways to meet the regulation. Wall components should either meet the guidance defining limited combustibility set out in the document, or meet the performance criteria in BR135, a technical standard for the fire performance of external insulation in tall buildings, which subjects full scale replica wall assemblies to a standardised fire test.

However in 2014, the Building Control Alliance (BCA) published additional guidance on the use of combustible cladding materials for buildings over 18 metres high. It said: “If no actual fire test data exists for a particular system, the client may instead submit a desktop study report from a suitable independent UKAS accredited testing body (BRE, Chiltern Fire or Warrington Fire) stating whether, in their opinion, BR135 criteria would be met with the proposed system.”

This meant that, rather than submitting a cladding system to a full fire test to BR135, you could essentially ask an expert to give their professional judgement on whether it would meet the standard if tested.

This ‘desktop’ approach rapidly took off, and became the basis of approval after approval in the three short years after it was introduced — even though it appears the BCA viewed this as a method of compliance that would only be used in limited circumstances.

As Kingspan put it in their own guidance on “routes to compliance” published in 2016, the desktop study report has become: “a commonly adopted method of demonstrating compliance with an increasing number of private and local authority Building Control Bodies (BCBs), as well as structural warranty and insurance providers.”

A cultural shift is needed. Buck-passing needs to become a sign of weakness and failure, accountability a mark of strength and success.

In 2015 the BCA issued further guidance offering a fourth method of compliance, though this now appears to have been withdrawn, and the original 2014 advice restored in its place. However, we have an idea what the 2015 guidance contained, because that same year the National House Building Council (NHBC) published a ‘technical extra’ on a variety of topics, including a discussion of the BCA’s then new fire guidance.

The NHBC report refers to this fourth option as follows: “If none of the above options are suitable, the builder may consider a holistic fire engineered approach for the entire building.”

The NHBC added that volume two of Approved Document B recognises this as an acceptable alternative approach to fire safety.

This essentially provided a route whereby the performance of the building as a whole, including all fire safety measures, could be considered within a standardised framework (there is a relevant British Standard) to determine whether or not it offers an acceptable level of fire safety.

In a presentation published on the website of the Council for Aluminium Building, Steve Evans of the BCA said that desktop reports should be “based on reasoned arguments/ facts not opinion” and should “justify any discrepancies between the tested and proposed build ups.” His presentation added that desktop reports should avoid “leaps of faith”.

He warned that applying data from dissimilar materials could lead to inaccurate conclusions.

After Grenfell, these warnings were reiterated by the BCA, which said that in the case of using options three and four to comply with Part B, any conclusions about the fire safety of an external cladding system resulting from studies must be “supported by hard test data and based on fact and not purely opinion”.

The BCA added that testing used to justify the conclusions of desktop reports should be “specified and carried out by UKAS accredited testing stations”.

But we know that despite this BCA advice, opinion kept creeping in. Evans noted in the same presentation that “reports from some fire engineers [are] still being based on opinion not fact.”

At the start of July, BBC Newsnight reported that it had seen two desktop reports by testing firm Exova Warringtonfire, which used the argument that a fire test would produce a similar result if either composite aluminium cladding or non-combustible ceramic tiles were installed outside of a combustible insulation material. Was this fact or opinion?

The reports argued that it was acceptable to use successful fire tests involving ceramic tiles as a guide to the likely fire safety of a cladding system using aluminium panels.

The aluminium panels in the two desktop studies contained fire retardants, unlike those at Grenfell Tower. Nonetheless, experts Newsnight spoke to expressed concern that the arguments advanced by the authors were not sufficiently evidence-based. These assessments, one expert told the BBC, “appeared to extrapolate an apple into an orange”.

Why did the desktop approach to certification gain such dominance, despite the fact that — relying as it did on extrapolations from actual tests — it was inherently less certain? Indeed, why was it offered in the first place?

It is not even clear that the BCA was the driver of the ‘alternative routes’ approach.

There is a suggestion that, rather, the guidance was an attempt to catch up with a runaway construction industry.

According to a 2016 Rockwool-sponsored continuing professional development (CPD) module in Building magazine, the BCA guidance was published “following the completion of a number of construction projects not compliant with Approved Document B or the guidance contained in BR135.”

But why not simply clamp down on non-compliant projects? Was there pressure not to “stifle innovation”? As a recent article in the Financial Times explained, so-called “functional regulation” – which sets out the goal of the regulation, rather than prescribing in law exactly how to achieve it — aims to leave room for flexibility and innovation in meeting the law.

One fire engineer was quoted in the paper as saying that with very prescriptive, conservative regulations, “fantastic buildings like the Shard . . . probably couldn’t be built.”

Given the sheer number of potential cladding build-ups that are possible, if the regulations were to insist on full testing for every system with combustible elements, far fewer combinations would be permissible.

Design options would become more restricted, buildings might become more expensive to build, and some products would lose market share (while others would gain it). Thus the desktop option took off.

Was the cladding on Grenfell Tower compliant with the regulations? The Department of Communities and Local Government, who publish the regulations, maintains that it was not.

It clearly wasn’t compliant with the wording of the regulation itself – the surface spread of fire was not adequately resisted. The components were not “of limited combustibility”. We now know that had the build-up been directly tested before it was specified, it would have failed. In other words, it failed to comply with either specific compliance route set out in Approved Document B.

Nonetheless, could the cladding build-up have been compliant with some of the recently- issued and more nebulous guidance, and thus acceptable to a building control officer?

In a statement released shortly after the fire, DCLG revealed the government was not itself certain at that stage – saying it was “possible” that there might be some whole-assembly tests using panels like those at Grenfell that complied, though it was not aware of any.

“We are also aware that some ACM [aluminium composite material] panels are accredited as having a ‘Class 0’ rating for the surface. But that, in the Department’s view, supported by expert advice, is a rating for the surface only and does not cover the limited combustibility requirement for the core or filler material within an ACM panel.”

We don’t yet know how this particular build-up was approved. But we do now know that an insulation and cladding build-up intended to replicate the one at Grenfell Tower failed fire testing by the BRE.

As Passive House Plus was going to press, the BRE was carrying out similar tests on five more cladding configurations, but results were not yet available. In practice, of course, many more than six possible combinations of materials are used as part of cladding systems.

For now, the government has advised the owners of 82 buildings known to have wall cladding that consists of aluminium composite panels with polyethylene filler in category three (the highest combustibility rating) and foam insulation that this combination does not meet current building regulations. These building owners are advised to undertake an immediate fire safety audit, put in place a plan to review the cladding system, and undertake remedial work — in particular to remove cladding. The expense and the anxiety of occupants in the meantime is immense.

The question now lingers: how did we get here? Did designers and specifiers become immersed in a culture where the industry regarded compliance with Part B as a paper challenge, rather than a matter of physics, and a matter of life and death?

An article written by a cladding manufacturer for the website Building Construction Design, published in January, discusses the challenge of keeping costs down while meeting both thermal performance and fire safety requirements.

“The risks of non-compliance can be high,” the article says, “firstly of prosecution under Building Control legislation, also litigation under health and safety legislation, such as the Corporate Manslaughter Act. This could potentially lead to fines and imprisonment.”

This kind of language is very common in industry literature. The risk of injuring or killing people is rarely mentioned.

Writing in Building Magazine, Mark Farmer, who reviewed the issue of construction labour for the UK government, warned that: “Confusion over cladding testing is already perpetuating the feeling that some of our most important industry standards are indeterminate, lack transparency and appear open to gamification or playing the system.”

The Fire Protection Association was blunter, saying that the way Part B was being applied “encourages value engineering to support a race to the bottom”.

So against a government background of deregulation and austerity, and driven by confusion over building regulations, the construction industry appears to have become more preoccupied with ‘tick-box’ compliance than with actually preventing fires.

 At the same time, the nature of modern construction contracting (see sidebar) now means responsibility is often passed down through chains of sub-contractors, with an emphasis on cost-cutting at each step of the way.

According to a report in the Guardian, in 2012 the original contractor for the Grenfell Tower refurbishment, Leadbitter, said the project would cost £11.3m. Planning drawings at this stage show that the architects and engineers had proposed cladding with a fire-retardant core, the paper reports.

The overall cost of the project was rejected as too expensive and the council appointed Rydon instead on a tighter budget of £8.7m.

According to the Guardian, Kensington and Chelsea Borough Council’s housing and property scrutiny committee was told that Rydon had “submitted the most economically advantageous tender, scoring highest on both price and quality”.

The Guardian and BBC both report seeing financial documents confirming that almost £300,000 was cut from the cost of the cladding system used on Grenfell Tower by changing from zinc panels with a fire retardant core to cheaper aluminium panels – apparently described internally as a “value engineering process”. It is not clear from the information shared by the BBC what grade of ACM panel was being considered at this point.

According to the Guardian, cuts were also made to the way the gas risers fitted inside the tower’s internal corridors were treated.

“About £60,000 worth of intended works to duct panels and ventilation grills for the risers were omitted, according to the documents,” the newspaper says.

And just weeks before the Grenfell disaster, the insurance industry warned the government of the dangers of flammable cladding on buildings.

“The Association of British Insurers told ministers in May that outdated building regulations should be reviewed because they had failed to keep pace with modern construction methods, including the installation of flammable surfaces,” the Financial Times reported.

Experts warned repeatedly about the risks of catastrophic fires in buildings with external cladding panels. “Nightmare scenarios include multiple-fatality building-engulfing fires,” warned a report from the firm Probyn Miers, experts in construction dispute resolution, who had studied the fires in the UAE.

Labour MP and former firefighter Jim Fitzpatrick, secretary of the all-party parliamentary group on fire safety and rescue, said successive ministers had “sat on” plans to review building regulations ever since the Lakanal House fire.

And while fire deaths have fallen by 30% in the last decade, between 2015 and 2016 this trend reversed by 15%, with a 5% increase in the number of fires attended. That was before Grenfell Tower.

Over the past decade, as construction boomed on the back of soaring prices and soaring rents, “innovative” buildings sprang up everywhere. And now a horrifying new prospect, that the shackles of regulation will be thrown off even further, rears its ugly head as Britain prepares to leave the EU.

Grenfell may be the worst, but it is far from the only construction scandal where the suspicion lingers that prioritising price over quality has wrecked lives. This is why Grenfell haunts me, and should haunt us all.

Just before filing this article, I visited Grenfell Tower. It is an ugly, disfigured mess: the track of the inferno, the upwards fade to black where the flames grew hotter and hotter still as they rose; the broken, twisted fixings standing starkly away from the structure, a skeleton tracing out the ghost of its deadly load. On a breezy weekday in late July, I visited Grenfell Tower, and there in the street I wept.

There, huge and devastated, is the physical presence, the physical consequence, of a thousand decisions made to get things done a bit more cheaply, to make a bit more money, to clinch that deal.

To do things that plenty of other people in the industry do, so therefore they must be ok. To see a building as a drawing, a programme, a calculation, a challenge, a victory, an expense, a labyrinth to navigate, a set of hurdles to overcome — but never as a home.

The police, the Crown Prosecution Service, and ultimately the courts will judge which, if any laws were broken. But beyond any doubt, this is a crime scene. Eighty people dead and many of them are still up there. Grenfell Tower is a mass grave. It hangs over west London, brutally reminding us all that our priorities have been very, very wrong.