Aluminium composite material (ACM) panels on the crown of Grenfell Tower, apparently used for purely “aesthetic” reasons, hastened the horizontal spread of the blaze and sent pools of burning polyethylene down onto the flats below.
That’s according to the latest evidence given at the Grenfell Tower Inquiry, the first phase of which is focusing on the narrative of events on the night of 14 June 2017 which resulted in the deaths of 72 people.
Giving evidence, Arup fire safety expert Dr Barbara Lane said she believed that the crown of the building to be a purely architectural feature with no provision to prevent the horizontal spread of fire around the crown.
“I don’t know what they thought it was. It’s just to make the top of the building look nice, I suppose,” she said.
Asked if she thought its was important “in the overall scheme of things”, she said: “Once the flame got up to level 23 in the first place, above flat 16, it appears then to have been able to travel horizontally in both directions through the crown, and the helicopter footage and other moving images show the flame front progressing but, more importantly, causing extensive pools of burning polyethylene to flow down to the spandrels above those flats and, more significantly, down other columns.
“It causes burning of the laterals and the ignition of more and more columns as that flame front progresses. So it’s significant in the context of causing, in the timing we saw at Grenfell, more columns being involved that way, and it is significant about what it did to the flats at level 23.”
No engineering functionality
The day before Dr Lane gave evidence, Prof Luke Bisby, chair of fire and structures at the University of Edinburgh, said that the only function of the crown he could see was as a “visual and aesthetic feature as opposed to having some specific engineering functionality”.
He said: “It wasn’t required. There was already a parapet beam and a safety grating at roof level. So it served no purpose other than an aesthetic purpose, as far as I can tell. If we have evidence otherwise I would like to hear it, but as far as I can tell it was purely an aesthetic feature.”
Asked if she agreed with Prof Bisby that the lateral spread of fire was most rapid at the crown, Dr Lane said: “Yes. I haven’t done timing analysis, but, yes, it was a highly effective flame front along the crown. I think I agree. At that time, yes, it was the most important horizontal spread. But later on, the other lateral flame fronts became important because the crown wasn’t involved anymore.”
When asked by the inquiry’s chairman Sir Martin Moore-Bick if it would have been a practical possibility to insert cavity barriers anywhere at the crown to stop the flame, Dr Lane said: “My view is no. The only way you could stop the crown from being a flame front on its own is to not clad it in a combustible material. Trying to detail in little breaks or cavities, in my opinion, is not a practical mitigation measure. The best mitigation measure would be not to have that material there at all. But I think I’m probably straying beyond my Phase 1 duties.”
Earlier this year, Dr Lane published a report for the inquiry in which she concluded that the refurbishment of Grenfell Tower created “catastrophic fire spread routes”, and determined that the rainscreen cladding system added to the building as part of its refurbishment between 2012 and 2016 was “non-compliant with the functional requirement of the Building Regulations.”
Phase one of the Grenfell Tower Inquiry continues.
