Approved Document B, Diagram 40, Judith Hackitt and the truth about Grenfell
A paragraph in Volume 4 of the Grenfell Tower Inquiry report opens up a wormhole which leads us to a government spin machine causing havoc in the aftermath of a major disaster
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“I’m going to have to write about Diagram 40 again”. That was the realisation (and sinking feeling) I had after reading Paragraph 48.30 of the Grenfell Tower Inquiry report (Volume Four).
I was reading Volume Four because this was supposed to be a post about how the inquiry has divided up responsibility between the various members of the project team, and some observations about what those judgements mean for construction across the board.
But I will, instead, park that until next week and return to writing about an old friend: the official building regulations guidance for fire safety, or as it is known in the industry, ‘Approved Document B’. And specifically, what it said (and didn’t say) about the appropriate standard for cladding panels.
What can sometimes get lost in the technicality of this part of the Grenfell Tower saga is an extremely important story, which reveals a probable attempt at a cover up by the government in the days immediately following the Grenfell fire, is a root cause of the utter mess we’ve made of building remediation in the seven years since and is also a partial explanation of why our attempts at reforming the industry have so far gone wrong.
Let me explain.
At the time Grenfell Tower was refurbished, the law required builders to design a building with external walls which “adequately resist the spread of flame”.
That was it. The statutory requirement covering the external walls is what we call “performance-based” or “functional”. It isn’t a long list of dos and don’ts but instead a standard which must be achieved, with the industry supposed to hire competent enough people to work out how do it without the government telling them.
The trouble is that this creates a good deal of uncertainty. How do you know you’ve complied with the functional requirements, without setting the wall on fire to check?
So alongside the functional requirements, we also publish non-mandatory prescriptive guidance which set out basic minimum requirements, intended as a guide to designers in how to comply with the overall standard.
But what we get as a result is a ‘race to the bottom’. Everyone treats the minimum standards in Approved Document B as the only requirements for compliance and everyone seeks the cheapest way to meet them. If a product meets the requirements of AD-B, it’s going on the building. Subtler questions about the functional requirements just aren’t asked in the cut and thrust world of a major construction job.
The big, big problem here is that the inquiry has now very clearly established that one of the critical standards in Approved Document B, namely Class 0, was not fit for purpose.
Highly combustible materials could obtain it, because it focused on the surface of a product, not its core. So if you had - for example - a cladding panel which was as combustible as petrol in its centre, but faced with thin sheets of aluminium, it might just pass.
This was not widely known. A misunderstanding had spread throughout the industry that conflated Class 0 with non-combustible. This was helped by deliberately misleading marketing, but I don’t think this was much more sophisticated than people thinking “well it’s got zero in it, so that means zero combustibility right?”
Since the mid-1990s, it should have been very obvious to government officials that they needed to get rid of Class 0. They never did, with the probable reason being a desire not to piss off the people who relied on it to sell their combustible plastic products, which I touched on in last week’s post.
This should have been a huge, immediate controversy after the Grenfell fire and for a while it was. We were writing about the deficiencies in government guidance at Inside Housing within 24 hours of the blaze and campaigners like Sam Webb and Arnold Tarling, who had been aware of the Class 0 problem for years, were giving emotional TV interviews where they pinned the blame for the fire on government deregulation.
This line of conversation did not go unnoticed in government. Behind the scenes, the government was becoming aware of the scale of its own fuck up. Melanie Dawes, permanent secretary at the department responsible for building regulations, had sat down with the relevant civil servants and gained some insight into the problems and the prior warnings which had been ignored.
She sent a text to Gavin Barwell (then the PM’s chief of staff and previously housing minister with responsibility for building regulations) just hours after the last resident escaped the tower. “Gavin, hope all is ok,” she wrote. “Wanted to let you know this terrible fire will highlight government delay in changing building regs. So you’ll want to be briefed personally from an ex-housing minister perspective as well as from a Number 10 perspective.”
Shortly afterwards, the government announced the inquiry which has just completed, and from then on all questions about its failure to amend guidance were met with the retort that we would have to “wait for the outcome of the inquiry”.
But the government actually had no intention of waiting. Instead, Philip Hammond, then the chancellor, went on the Andrew Marr Show and claimed that the cladding used on the tower was banned in the UK.
When The Times ran a story suggesting it was not, and that our defective Class 0 standard might be to blame, government press officers covertly approached industry experts with a pre-prepared script they wanted them to adopt which would support the government line.
The argument they were making ran like this (and this is where we get technical, so bear with me).
In Approved Document B, the standards for the external surfaces of walls are set out in paragraph 12.6, which refers the reader to Diagram 40. This (pictured below) said that in buildings above 18m, the appropriate standard was Class 0 or Euroclass B.
The document also contains a further provision, at paragraph 12.7, which covers insulation materials, and says that any insulation product or filler material used above 18m, is supposed to meet the standard of “limited combustibility”.
This is a much tougher standard than Class 0, and would result in anything combustible being banned (unless they had followed a large-scale testing route to compliance, which I will save for another day).
The problem is that cladding of the type which was used on Grenfell is not insulation. It doesn’t serve an insulating role. The insulation is a different material, which sits behind it and the cladding is a ‘rainscreen’ - it protects the building from the weather and gives it a smooth architectural finish.
So a natural conclusion would be that the standard for this product (the external surface of the wall) is found in Diagram 40, which makes it Class 0, and the standard for the insulation (which sits behind it) is found in paragraph 12.7 on insulation, which makes it limited combustibility. Two different products, two different standards.
Still with me? Good. The trouble for the government was that if this was the correct way of reading the document, they had screwed up. An outdated standard had been allowed to persist in guidance for far too long, and combustible cladding products had flooded the market as a result.
And so, this was denied. The government’s argument was that the words “filler material” in the paragraph about insulation applied to the slim bit of polyethylene inside the cladding panels, despite this not actually being insulation at all.
A letter, signed by Melanie Dawes and drafted by the civil servant responsible for building regulations, Brian Martin, (who you may remember from my previous writing) went out on 22 June 2017 (eight days after Grenfell), with an asterix on it which confirmed this new reading.
“For the avoidance of doubt,” it said, “the core (filler) within an aluminium composite material (ACM) is an ‘insulation material/product’, ‘insulation product’, and/or ‘filler material’ as referred to in Paragraph 12.7... of Approved Document B.”
The letter said that this meant “any element” of a cladding system needed to be “limited combustibility”. This was exactly what ministers told us we could not yet do: prejudging the outcome of one of the critical questions the inquiry was going to have to answer. And they were doing so in a way which was highly favourable to their own position.
Mr Martin was asked about this letter when he gave evidence. He accepted that saying “any element” of a cladding system was required to be limited combustibility was “a false representation”. But he denied that the letter as a whole was a “planned, deliberate and underhanded attempt by you and those around you to rewrite history… in order to protect the government’s position”.
All of this brings me on to paragraph 48.30 (volume four) of the Grenfell Tower Inquiry report, which discusses the guidance which was in force when the tower was refurbished.
Addressing the question about filler head on, it says: “We do not agree with [the argument]... “filler” naturally means a material… used to fill gaps of an unplanned or occasional kind.
“It is not apt to refer to the core of a composite cladding panel which is an integral part of the finished product. We derive further support for our conclusion from the fact that we have not seen any evidence that the core of a composite panel was described as ‘filler’ by anyone in the building industry before the Grenfell Tower fire.”
And so, there we have it - we waited for the inquiry, and it confirms the government’s official letter was wrong. The panel’s view is - effectively - that the government misinterpreted its own guidance in the days immediately after Grenfell and did so in a way which defended its own position.
This has had real-world consequences. Part of the reason why the government screwed up the early stages of the cladding crisis so badly is because they expected to be dealing with a few dozen instances of non-compliance, not an entire country where the buildings are routinely made of combustible plastic.
When they insisted that “all elements” of an external wall were required to be limited-combustibility, it meant anything combustible on the outside of a building failed to meet the required standards and needed remediation.
This resulted in the utter chaos of EWS1 forms, mortgage providers effectively moving out of the high-rise market, and people being trapped in their homes. This is a position we are still unwinding.
It also meant we stopped seeing the wood from the trees: there was no distinction between buildings which might be fine, but had some patches of moderately combustible decorative cladding and buildings (like Grenfell) which were literally wrapped in petrol.
Dame Judith Hackitt’s Independent Review of Building Regulations, which was carried out in 2017 and early 2018, also followed the government line. Her own forward to the report said it aimed to understand why there had been a “widespread use of aluminium composite materials which did not meet the limited combustibility requirements of building regulations guidance”. The answer was actually fairly simple: this was not the requirement of building regulations guidance.
Her final report (and the subsequent legislation which came into force in 2022) therefore diagnoses the illness incorrectly and prescribes the wrong cure. Her regime is based on the conclusion that dangerous buildings are only ever a result of a failure to follow or enforce guidance, and so they tighten that up without actually fixing the broken guidance.
While it is a regime which has some positive elements, one of its key shortcomings is this failure to understand that we need a better industry and better regulations, not just the former.
(I am going to note that not everyone swallowed the government line, this a detailed take down in the specialist press has stood the test of time reasonably well).
It is important to be clear about why this matters.
The understanding that Class 0 cladding was required for Grenfell does not get anyone responsible off the hook, but simply clarifies which hook they are on and why. The company (Arconic) which sold the Reynobond PE55 used on Grenfell, had indeed marketed it as a Class 0 product.
But the Class 0 test they had used to justify this claim was on a fire retardant panel - not the one used on Grenfell. When Reynobond PE55 was tested to a Class 0 standard, it failed.
They also elected to leave their product on the market, despite knowing the horrible danger it posed in cassette form and that it would not (as a result) be capable of meeting the UK’s functional requirements for a building like Grenfell, even if it did have a Class 0 rating.
The construction team who refurbished Grenfell used combustible insulation, so would have been in breach of the statutory guidance, even if they had used a genuinely Class 0 cladding panel.
And since the ‘functional’ system of regulation actually imposed a legal responsibility on them to build a wall which “adequately” resisted the spread of flame, not to blindly follow guidance and specify a product linked to dozens of fires around the world, they would have still been in breach of the law. This is especially true (in my view) of the supposed experts on the job (the cladding subcontractor Harley and the fire engineers Exova).
That may seem harsh (builders and designers will work to minimum standards), but it is how functional requirements operate, and it is the industry itself that has lobbied for them. They can’t disown them when it goes wrong.
But we need the truth to be told about Class 0 because the truth matters. There are plenty of projects out there which are being remediated despite the designers following the government guidance and specifying products which complied with it. And the government - its former and current ministers and officials - needs to cop the blame for that.
The whole story of how Class 0 ended up staying in guidance over the decades is one of deliberate prioritisation of industry profits over human lives by the system of government which should protect us. That needs to be understood as a key part of what gave us Grenfell.
It also matters for reform. The report criticises the system of functional headline regulations and prescriptive guidance in Approved Document B in the following terms.
“One striking feature of the evidence was the extent to which many construction professionals have routinely regarded the statutory guidance as containing a definitive statement of the requirements of the Building Regulations,” it said.
“Many construction professionals appear to be uncomfortable with the broad language of functional requirements… and want to be told what is expected of them and in any event many are not competent to translate the general language of the functional requirements into decisions about the choice of materials or methods of construction.”
This is a totally accurate criticism, in my opinion. But the inquiry’s fix for it is wrong. The inquiry recommendation is for an overhaul of Approved Document B, a warning that following it might not result in compliance with regulations and a statutory requirement to appoint a fire engineer to advise on higher risk buildings.
But a better way might be to accept that the industry does indeed need “to be told what is expected of them”. This is a troubled sector of the economy where narrow margins and time pressures will generally win out. It is not going to transform into a highly competent, highly ethical, highly expert industry overnight and the fire engineers it appoints could end up being just as client-serving and slippery as the professionals involved in the Grenfell job in the worst cases.
To me, the whole miserable saga of Class 0 proves that there will always be a race to the bottom. Manufacturers will exploit the requirements of guidance as far as they can to get their cheapest product to market and value engineering will ensure that it is the cheapest product which wins the specification. This is the industry, and all the thought leadership pieces and conference events in the world won’t change that.
So the answer should be to grasp the reality that the industry will ‘race to the bottom’ and lift the level which we set as the ‘bottom’. The lowest standards in guidance have to be appropriately safe. If this means setting them high, costing everyone a bit more money, forcing some products out of the market and moving to a more US-style prescriptive set of building codes, so be it. The best way to lift standards is to lift standards. Now that we can finally set the Class 0/filler debate to bed it is time to say that clearly.
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If you pay £40 or more for an annual subscription, I will send you a signed copy of my book. Or you can buy a copy here.
Absolutely right. The best way to lift standards is to lift standards.
It would have been possible at any moment after 1991 to remove Class 0 to BS 476 Parts 6 and 7 and insist upon "limited combustibility" whether to BS 476 Parts 4 and 11 or as Class A2 to BS EN 13501-1, as became Table A7 in the statutory guidance. 1991 was only four years after the BSI committee had introduced a water-cooled frame into BS 476 Part 7 explicitly to test thermoplastics. Thereby fundamentally changing the meaning of Class 0 that had been finalised in 1976 and included in the first Approved Document of statutory guidance in 1985.
It would have been possible not to lie about the statutory guidance after 14 June 2017. Instead the Grenfell bereaved, survivors and relatives, and all those with uninsurable and unsellable homes facing a waking watch bill and the impossibility of bringing countless legal actions against parties that either don't now exist, or are multi-national corporations, have been given the run-around.
At the centre of this in my view is the meaning of Sections 6 and 7 of the Building Act 1984.
The difference between bad faith and good faith actors. The law is silent, and many want to assume strict liability on good faith actors.
https://www.linkedin.com/posts/ableyian_approved-document-b-diagram-40-judith-hackitt-activity-7246897851362852865-dOqg