Report lays bare the failures that caused the fire to spread, killing 71
A report prepared as part of the police investigation into the Grenfell Tower fire has uncovered calamitous deficiencies in the installation of the windows, cavity barriers and cladding system, and their failure to meet building regulations according to the Evening Standard.
The 210-page interim document, by fire investigation experts BRE Global, is set to dramatically assist the Metropolitan police in their wide-ranging investigation. It was leaked exclusively to the Standard and recounts in forensic detail how the original concrete building was turned from a safe structure into a tinderbox by the refurbishment between 2014 and 2016.
It not only finds the cladding material and insulation was combustible, but also exposes hitherto unknown areas of incompetence relating to the design and installation of the windows and cavity barriers. The latter are critical in closing the gap between the inner and outer skins of the building to prevent a chimney-like effect in the event of a blaze.
It reveals how in the early hours of June 14 last year, the fire started in a single fridge-freezer in a single flat on the fourth floor; travelled through an open window within a metre of the fridge; took hold in the cladding; and consumed an entire 24-storey, 70-metre-high building. A total of 71 lives were lost.
For the first time, the truth of how the refurbishment fell short of building regulations, and allowed a catastrophe to happen, is laid bare.
The first conclusion of the report is that the fire would not have spread beyond Flat 16 — the flat of origin — and would not have claimed even a single life if the original facade of the building had not been re-clad.
It states that the 2014-16 refurbishment failed, in several fundamental areas, to meet fire safety standards set out in the building regulations — known as Approved Document B. Taken together, these areas proved critical for the rapid spread of flames across the length and breadth of the building.
The report, dated 31 January 2018, says: “Grenfell Tower, as originally built, appears to have been designed on the premise of providing very high levels of passive fire protection.
“The original facade of Grenfell Tower, comprising exposed concrete and, given its age, likely timber or metal frame windows, would not have provided a medium for fire spread up the external surface. In BRE’s opinion … there would have been little opportunity for a fire in a flat of Grenfell Tower to spread to any neighbouring flats.”
The experts found instead that “deficiencies” in the construction of the new facade provided fuel for the fire to spread — and that it did so with such ferocity that if the original building had been built to less stringent modern standards of fire resistance, “it is likely the Tower would have collapsed, whether fully or partially”. The report identifies five significant breaches of building regulations that appear directly implicated in the loss of life:
Gaps that fanned fire
The cavity barriers — which in the event of fire are meant to expand and seal the gap between the concrete surface of the building and the cladding insulation — were of “insufficient size specification” to perform this vital function.
Some cavity barriers were installed “upside down” or “back to front”, further retarding their effectiveness.
They were “designed to close a gap of 25mm”, but the actual gap “measured up to 50mm”.
The result was to create a catastrophic chimney-like effect in the gap between the cladding and the concrete surface that “provided a route for fire spread”.
Window frames that helped flames spread
The window frames were “significantly narrower than the gap between the concrete surfaces of the columns, 150mm narrower”, leaving large gaps at either end.
These spaces were filled by a rubberised membrane, rigid foam insulation and uPVC lightweight plastic panels — but crucially “none of the materials used would be capable of providing 30 minutes fire resistance”.
The result was “a direct route for fire spread around the window frame into the cavity of the facade … and from the facade back into flats”.
This has added importance, as the first obstacle the fire encountered as it escaped from Flat 16 was the window frame which provided “fuel” instead of a barrier. BRE says: “The construction of the window did not provide any substantial barrier to fire taking hold on the facade outside.”
The insulation used was “combustible” and “provided a medium for fire spread up, across and within sections of the facade”. BRE notes that the 75mm insulation foam used on most of the spandrel beams had “no markings to identify the manufacturer of the foam”, unlike the 100mm Celotex foam insulation used on the columns. BRE records this oddity of the mystery manufacturer but does not further distinguish between the foam types, concluding both were “combustible”.
The aluminium composite material used in the facade had a polyethylene (plastic) core that “appears to be highly combustible” and “appears to have provided a medium for fire spread up and across the facade”.
Lack of door closers
The “absence of door closers” on many front doors to flats, contrary to building regulations, resulted in a significant number of doors being inadvertently left open when residents fled.
“Where this occurred, the fire in each flat appears to have emitted large quantities of smoke and later fire directly into the immediate lobby, and these have gone on to affect the lifts and single stairwell”.
A chart showing the percentage of working versus non-working door closers from floors 4 to 23 (120 flats)
This is a major failing because it created “shortcomings in compartmentation” of the fire and would have affected residents’ life chances as they sought to escape down the single stairwell.
BRE notes that individual breaches relating to the cladding system assume far greater importance when “considered in combination as opposed to when they occur in isolation”.
Firefighting facilities were “deficient”, hampered by poor access and lack of installation of a wet rising main.
There was room for just “a single fire engine” on the hard standing at the base of the east side of the tower, as other sides of the tower were not accessible due to landscaping. This single fire engine would be “unlikely to provide sufficient pressure and flow of water for firefighting at the top of the tower” using the dry rising main.
The report says: “A building of Grenfell’s height ought to have been fitted with a wet rising main [which contains water at all times] as part of the refurbishment; instead the existing dry rising main [which has to be supplied from a fire engine] was extended and modified.” BRE cites two other breaches of building regulations — the absence of a sprinkler system and the single stairwell being 8cm too narrow. However it does not necessarily regard these weaknesses as directly responsible for loss of life. It adds that the stairwell would have been “difficult and expensive to change as part of any refurbishment”.
The draft report was submitted to the Metropolitan Police Service so that its interim conclusions could speed up “other parts of the MPS-led investigation”, including gathering documentation and interviewing contractors. BRE was asked to achieve three aims:
“To establish the circumstances surrounding as many deaths resulting from the fire as possible;”
“To establish any failings of duty of care owed to victims of the fire, both fatalities and surviving residents;”
“To provide expert witness support in relation to any criminal prosecution, public inquiry or inquest.”
The Standard understands, from a separate source, that the police investigation has already downloaded over 30 million emails and documents from the servers of Kensington and Chelsea council and the Tenant Management Organisation, and that they are beginning to trace and interview about 500 key contractors and sub-contractors involved in the refurbishment.