An expert witness has told the Grenfell Tower inquiry that the design and installation of cladding on the refurbished Grenfell Tower were not compliant
On the first day of evidence at the inquiry yesterday (4 June), a report from Arup fire engineering specialist Barbara Lane presented details of why elements of the refurbishment did not meet the Building Regulations.
Then AJ’s sister title Construction News reports that Lane’s report singled out the design and installation of new windows and rainscreen cladding, which are believed to have combined to allow the fire to escape from the flat where it began and spread rapidly across the building’s exterior.
Grenfell’s rainscreen cladding has come in for scrutiny for its role in the spread of the fire, and Lane’s analysis found it was not compliant with Building Regulations at the time it was installed.
I have found no evidence that Building Control were either informed or understood how the assembly performed in fire
She said: ‘I have found 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 performed in fire.’
She added: ‘I conclude the system could not adequately resist the spread of fire over the walls having regard to height, use and position of the building.
‘The building envelope system, designed and installed during the 2012-2016 refurbishment, was therefore non-compliant with the functional requirement … of the Building Regulations 2010.’
Of particular concern was the use of a polyethylene filler in the Reynobond aluminium cladding screen.
Lane’s analysis found vertical and horizontal fire-stopping in the cladding cavities had been installed, but done so ‘incorrectly’.
The design and construction of the windows and cladding meant every flat was effectively connected in the event of a fire
New windows installed when the block was refurbished were also highlighted, with the report stating that they were smaller and did not sit flush to the concrete wall.
The windows were ‘surrounded by combustible material’ in the form of Styrofoam, which produced ‘large quantities of black toxic smoke’ and supported the quick spread of the fire.
This detailing ‘increased the likelihood of a fire breaking out of the flat’, Lane said.
Once outside, the fire was able to get into the cavities in the rainscreen cladding, which contained the combustible polyethylene.
Lane said the built design and construction of the windows and cladding system meant that every flat on every storey of the building was effectively connected in the event of a fire. As originally designed, each flat should have acted as a ’separate fire-rated box’.
‘There were multiple catastrophic fire-spread routes created by the construction form and construction detailing,’ she said.
This meant the advice to residents to stay put while the fire was tackled was not ‘realistic’.
Lane’s report also said that the apartment doors that had been replaced in 2011 were not compliant.
‘This non-compliance would have contributed to the failure to prevent the spread of fire and hot smoke from the flat to the lobby,’ she said.
Grenfell Tower had a fire-fighting lift, but this too was not designed in accordance with regulations from 2013.
On the night of the fire, the lift failed to work and firefighters had to move equipment on foot.
A dry-riser installed for the fire brigade to use to pump water was also found to be non-compliant with design guidelines when it was installed.
A separate report by Luke Bisby of Edinburgh University, released by the inquiry today (5 June), said polyethylene presented ‘a highly combustible liquid fuel’ for the fire to spread across the exterior.
Photos from the night of the fire showed melted and burning droplets of what was likely polyethylene filler falling, which could have spread the fire to other areas.
The Hackitt report released last month was heavily critical of the construction industry and called for a radical overhaul of high-rise building design, construction and refurbishment.