The cladding used at Grenfell Tower was never tested, did not comply with fire regulations and was incorrectly installed, a group of expert reports has concluded.
The rainscreen cladding was deemed so flammable that the fire brigade’s Stay Put strategy should have been completely abandoned at least an hour before the building was evacuated, according to reports submitted to the Grenfell Tower Inquiry.
Furthermore none of the investigating experts were able to find proof that any fire safety tests were ever carried out on the Reynobond 55 PE rainscreen cladding prior to the blaze.
In fact, the inquiry’s lead counsel Richard Millett QC revealed that the manufacturer of rainscreen cladding Arconic accepts that its product “was not of limited combustibility for the purposes of the building regulations”.
Millet added that during the company’s opening submission Arconic stated that its product’s feasibility “should have been obvious to any construction professional”.
In his report, CS Todd managing director Colin Todd, one of the expert witnesses in the inquiry, said that “no BS8414 tests were carried out” on the cladding before the fatal blaze took place.
Subsequent testing has since taken place and has found that the material often fails to meet building regulations.
In a separate report, Arup’s leader of fire safety engineering Dr Barbara Lane also said that there was “no evidence yet that any member of the design team or the construction team ascertained the fire performance of the rainscreen cladding system materials, nor understood how the assembly performed in fire.
“I have found no evidence that Building Control were either informed or understood how the assembly would perform in a fire.”
Lane concluded that “multiple catastrophic fire-spread routes” were created during the cladding construction.
Her report said that the cladding type and assembly meant that “any individual flat of fire origin was no longer in a separate fire rated box” and therefore a Stay Put strategy for residents in the event of a fire was “not a realistic basis for fire safety design in this building.”
Consequently Lane believes that the building should have been evacuated at around 01:40, an hour before the Stay Put strategy was abandoned.
Her report concluded that there was an “early need for total evacuation of Grenfell Tower […] I am unclear about the basis for delaying the formal end of the Stay Put strategy between 01:40 and 02:47. I am particularly concerned by the delay from 02:06 when a major incident was declared, to 02:47.”
University of Edinburgh School of Engineering professor of fire and structures Luke Bisby also blamed the poor installation of the cladding in his report.
He said the fire most likely spread to the cladding via gaps or holes which formed in polymeric window framing boards that surrounded the kitchen window, and also through the weatherproofing membrane and thermal insulation - all of which were installed during the 2012-16 refurbishment.
He stated:“The fire most likely then penetrated into the back of the cladding cavity and ignited the polyethylene filler material within the aluminium composite material (ACM) rainscreen cladding cassettes that form the majority of the building’s exterior surface.”
Bisby added: “The primary cause of rapid and extensive external fire spread was the presence of polyethylene filled ACM rainscreen cassettes in the building’s refurbishment cladding system.”
Bisby identified several other factors that may have also contributed to the fire’s spread including:
- The use of combustible insulation products in the cladding system
- The presence of extensive cavities and vertical channels within the cladding system
- The use of combustible insulation products within the window framing assemblies
- The architectural crown detail at the top of the building and the cladding rainscreen details at the top of the building’s perimeter columns appear to have played significant roles in the lateral progression of fire spread around the building
In total five expert reports have been published detailing the cause of the fire and why it spread so quickly.
Faulty windows and non-compliant external and internal fire doors have also been identified as factors in spreading the fire which claimed 72 lives.
The release of the expert reports coincided with the first day of formal evidence, in which lead counsel Richard Millett QC said that the inquiry would “lay bare the truth about what happened” asking: “How did so many people sign this building off as safe? Was saving money put before saving lives?”
He added: “The fundamental question which lies at the heart of our work is how, in London in 2017, a domestic fire developed so quickly and catastrophically that an entire high-rise block was engulfed. Leaving hundreds without a home, their possessions destroyed, their precious mementos in ashes, their families shattered their community devastated, their lives permanently scarred and for an inheritance an abiding sense of injustice, betrayal and marginality, leading to an overwhelming question of ‘why?’”
The inquiry into the fire at the 24-storey Grenfell Tower in North Kensington, London, in the early hours of 14 June 2017, is split into two phases, which will run in parallel.
The first examines what actually happened in the early hours of the morning when the fire broke out. The second phase looks at the refurbishment and how the building was exposed to such a fire risk.
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