By Plastics News Europe
London — The fire which killed at least 79 and virtually destroyed Grenfell Tower was an accident that was ‘preventable’ following ‘years of neglect,’ in the words of London Mayor Sadiq Khan.
Meanwhile, there are reports that the supplier of exterior composite cladding that has been the focus of investigations into the fire’s spread has stopped selling the panels for high-rise buildings.
On June 23, London Metropolitan Police detective superintendent Fiona McCormack announced that the police had expert evidence showing the fire was not deliberate and that it had started in a faulty Whirlpool Hotpoint fridge-freezer.
However, the fact that the fire was able to spread so quickly from a single flat to the entire building, instead of being contained, is almost certainly due to its ability to reach external cladding and insulation. That was installed when the 1970s block was refurbished in 2015-2016, investigators said.
As part of the project, the concrete structure was fitted with new windows and new aluminium composite rainscreen cladding. Two types were used: Reynobond, which consists of two aluminium sheets with a polyethylene core sandwiched in between, and is produced by New York City-based Arconic; and Reynolux prepainted aluminium sheet, also from Arconic. Polyethylene is a thermoplastic material, which can melt and drip as it burns, spreading the fire.
Beneath these sheets, and fixed to the outside of the walls of the flat was Celotex RS5000 PIR thermal insulation, from Celotex, a Saint-Gobain company. The material has a Class 0 fire rating, but it is ultimately combustible and deadly hydrogen cyanide fumes can be produced, according to the Building Research Establishment (BRE), a UK-based building science center.
In its report: Fire performance of external thermal insulation for walls of multi-story buildings, BRE describes how such a cladding system can cause fire to spread: ‘The mechanisms by which fire can spread externally include combustible materials and cavities — either as part of a system, or those created by delamination of the system or material loss during the fire. Once flames enter a cavity they have the potential to travel significant distances, giving rise to the risk of unseen fire spread within the cladding systems.’
It added: ‘flames become confined or restricted by entering cavities within the external cladding system, they will become elongated as they seek oxygen and fuel to support the combustion process. This process can lead to flame extension of five to 10 times that of the original flame lengths, regardless of the materials used to line the cavities.’
In her June 23 statement, detective superintendent McCormack also confirmed that ‘preliminary tests show the insulation samples collected from Grenfell Tower combusted soon after the test started.’
She said that the tests carried out as part of the investigation were ‘small scale,’ but ‘what we are being told at the moment by the Building Research Establishment is that the cladding and insulation failed all safety tests.’
The UK’s Metropolitan Police says it is considering manslaughter charges, as police continue to look at the involvement of various companies who played a role in the renovation of the building.
Since the blaze, the British government has tested 600 tower blocks across the country for cladding safety. 60 blocks have failed, leading in some cases to the mass evacuation of their inhabitants.
Sajid Javid, a member of the UK Parliament and secretary of state for communities and local government, commented on the cladding testing failure rate, ‘interim safety measures that should be taken immediately where it has been determined that a building has Aluminium Composite Material [ACM] cladding that is unlikely to be compliant with the requirements of the current Building Regulations,’ he said.
‘A combustibility testing program for ACM cladding is running around the clock at [BRE]. This is able to test 100 samples a day — and if needed, yet further laboratory capacity could be provided,’ he said.
‘We expect that authorities and landlords are very sensibly giving the highest priority to buildings with which they have most concern. But we should not be in the position where buildings have such cladding on them. How this occurred — and preventing this from happening again — is likely to be a key question for the public inquiry.
‘It is important to stress that cladding itself is not dangerous, but it is important that the right type is used,’ he concluded.
Meanwhile, Celotex announced ‘In view of the focus on rainscreen cladding systems and the insulation forming part of them, Celotex believes that the right thing to do is to stop the supply of Celotex RS5000 for rainscreen cladding systems in buildings over 18 m tall with immediate effect, including in respect of ongoing projects, pending further clarity.’
Arconic apparently is taking similar steps. On June 26, multiple news outlets reported that the company will stop selling the PE core composite panels for use in high rises.
‘Arconic is discontinuing global sales of Reynobond PE for use in high-rise applications,’ the statement says. ‘We believe this is the right decision because of the inconsistency of building codes around the world and the issues that have arisen in the wake of the Grenfell Tower tragedy regarding code compliance of cladding systems in the context of buildings’ overall designs. We will continue to fully support the authorities as they investigate this tragedy.’
Reynobond PE is rarely used on towers in the US or many European countries. In the UK, the product was banned for uses higher than 18 m, although some of Arconic’s product brochures say the panels are only suitable for use up to 10 m (32.8 feet) in height. Grenfell Tower is 60 m (196.8 feet) tall.
McCormack said the investigation into how the fire spread will be exhaustive and the scope and scale may grow. Individuals or organizations could be prosecuted.
‘Whilst of course we are examining, with experts, the aluminum paneling, we are also looking at the entire exterior of the building,’ she said. ‘What that means is the aluminum composite tiles, the insulation behind it, how the tiles were fixed to the building as well as how it was installed. Our tests will look at each aspect individually as well as how they all worked together as part of the building’s cladding. Preliminary tests show the insulation samples collected from Grenfell Tower combusted soon after the test started.’
Investigators will ‘fully and impartially go where the evidence takes us,’ McCormack said.
Catherine Kavanaugh, a staff reporter for Plastics News, contributed to this report.