Testing times: Public inquiry

The details in Dr Barbara Lane’s expert report of what went wrong at Grenfell Tower are shocking and a sad indictment on the state of some elements of the construction industry.

The report is a catalogue of failures: a fire in a domestic appliance – not an unusual occurrence – spreads to the external cladding through flammable elements around the windows and up and along the building because of the flammable nature of the external cladding panels and a failure to fit cavity barriers correctly.

Front doors to individual flats failed to perform as claimed, allowing smoke and fire to pour out into the lobbies. The smoke ventilation system didn’t comply with the regulations and failed to operate as intended, allowing the stairwells to fill with hot smoke. Water couldn’t be got to the top of the building using the risers because these were inadequate. And to cap it all, the fire brigade continued to tell residents to stay put even after the fire had spread up the exterior to the top of the building.

There is a strong case that those working on multiple-occupancy tall buildings and other buildings should have the competence to make the right decisions to ensure these are safe

Lane goes much further and examines the fire performance of the different elements used in the building, the product testing regime, the adequacy of the guidance in Part B of the Building Regulations and the competency of those involved in designing, building and checking the refurbishment works at Grenfell Tower. Nothing and no one comes out of this well.

Lane questions the adequacy of BS 8414, the standard used for full-scale testing of cladding systems, saying the test panels should include openings such as windows to better replicate real world conditions as called for by the insurance industry.

Not that this matters much, because Lane couldn’t find any evidence that a cladding system fitted with polyethylene-cored aluminium panels had ever been tested to this standard, inadequate or not. It wouldn’t have the remotest chance of passing the test as polyethylene is highly flammable. It starts melting at 120ºC and would drip out from between the aluminium. At higher temperatures the thin aluminium skins would simply peel away leaving sheets of polythene without any protection.

Nor could she find any evidence that there was “any understanding by any member of the design team or construction team, nor by the approving authority that the cladding system was either combustible or in breach of building regulations”.

The guidance in the regulations comes in for stick too, giving further credence to those experts who claim that ambiguities in Part B have resulted in the widespread fitment of combustible polyethlene-cored aluminium [ACM] panels to tall buildings. Lane said the guidance in Part B was contradictory and needed urgent change. Guidance on the fire performance standards of external cladding should be changed to allow only non-combustible materials. The government’s interpretation, as stated after the Grenfell fire, that “filler materials”, defined as of limited combustibility, should include the core of external cladding panels, was dismissed by Lane who said there was no technical evidence anywhere that backed this up.

It will be for the lawyers to argue as to whether the government has been spared hugely expensive legal action from those who may have fitted ACM panels on the back of this flawed guidance, by Lane’s conclusion that the system at Grenfell, and others like it, would fail the functional requirement of Part B. This states that “the external wall of the building shall adequately resist the spread of fire”. In other words, it is arguable that it was the design and construction team’s responsibility to ensure that any cladding system on this external wall would have resisted the spread of fire, even if the guidance wasn’t clear about the fire performance of external cladding panels. 

These conclusions take us neatly to Hackitt’s report, which majors on the dangers of prescriptive guidance and the need for the industry to take responsibility for complying with the Building Regulations. Experts have warned that there are many in the industry who are dependent on prescriptive guidance as they lack the expertise to make critical decisions about complex building safety issues. But Lane’s findings reveal how a culture of flawed prescriptive guidance and design and construction teams’ failure to properly interrogate the fire performance of cladding systems may have resulted in the widespread fitment of flammable material to the outside of tall buildings. There is a strong case that those working on multiple-occupancy tall buildings and other buildings should have the competence to make the right decisions to ensure these are safe.

Given this damming indictment of all those associated with the refurbishment of Grenfell Tower it is sad, although perhaps not surprising given the threat of criminal proceedings hanging over all the parties, that on Monday Richard Millett QC, counsel to the inquiry, felt compelled to warn the companies and organisations called to give evidence not to “indulge in a merry-go-round of buck passing”. For the benefit of the wider future of this industry, let’s hope those companies and organisations take note.