Was the cladding entirely to blame and could it happen again?
Q Did the cladding on Grenfell Tower break regulations?
AThe Department for Communities and Local Government says Reynobond PE (polyethylene) – the part-plastic cladding on Grenfell – is banned by building regulations for towers over 18 metres high. But the industry says it is less clear cut. Dr Stephen Ledbetter, a former director of the Centre for Window and Cladding Technology, said the rules were “not explicit”. The 2010 regulations state: “The use of combustible materials in the cladding system and extensive cavities may present such a risk in tall buildings.”
Q Where in the world is the cladding banned?
AThe Grenfell cladding was banned in Germany in the Eighties on towers above 22 metres high. Panels without flameretardant cores are also banned on 15-metre high American blocks. Angela Constance, Scotland communities secretary, said her country’s 2005 regulations ruled that cladding “should” be non-combustible on high-rise buildings.
Q So was it the cladding that spread the fire, or the “chimney effect” of flames spreading in the gap between the insulation and cladding?
AConcrete columns surrounding the tower may have created a void that sucked up the flames, allowing it to spread from the fourth floor to the 18th in only eight minutes.
“The greater the gap, the more it acts like a chimney. It is one line of the investigation,” a source told the Telegraph.
Simon Taylor, who has fitted cladding to 25 local authority tower blocks as director of Yorkshire-based Northern Heights, believes this was the biggest factor. He said: “When the fire gets behind these columns, it creates this chimney-flamethrower effect.”
But Dr Ledbetter said horizontal bands built on the tower would have quelled the chimney effect. “The main problem is the rainscreen panels that have a polyethylene core.”
Q Would sprinklers have saved lives?
AThe Fire Protection Association (FPA) has said more sprinklers would “undoubtedly” have saved lives and they have also been recommended in a 2004 government report and at the inquest into the 2009 Lakanal House fire that killed six people. “Whether they’d have stopped that fire spreading at the speed it did up the outside of that building is another matter,” said Jon O’neill, of the FPA. “But [sprinklers] would have created an environment where it would have been easier to rescue people and increase survivability.”
However, Mr Taylor said he thought sprinklers were a “red herring”.
Q Were the victims killed by cyanide gas from burning insulation?
AManufacturer Celotex has said that the insulation would have released “toxic gases”. King’s College Hospital also confirmed that three of its 12 Grenfell patients were treated with the cyanide antidote Cyanokit.
Richard Hull, professor of chemistry and fire science at the University of Central Lancashire, said the burning foam insulation would have released “hydrogen cyanide and carbon monoxide, which cause rapid incapacitation when inhaled, preventing escape”.
Q Why was the stairwell a deathtrap?
ATower block stairwells are usually designed with one-hour fire-resistant doors, and in many cases, there are two external staircases. But Grenfell had just one staircase that ran up towards the centre of the building. One witness allegedly said she could not navigate the staircase because of smoke at 1.29am, which was about half an hour after the first 999 call.
Q Is Grenfell a one-off or could such a “perfect storm” of circumstances be repeated?
AExperts say a similar disaster is possible. There are towers across the country with similar features. Mr Taylor said: “Unless things are rectified it will happen again. There are other tower blocks with these triangular columns and that’s what provided oxygen for the fire.”
Q What is the root cause: austerity or laziness?
AMr Taylor said: “It’s laziness, it’s a lack of professionalism and it’s also about salesmen selling materials rather than engineers.”
Dr Ledbetter said: “As I understand it, a contractor was selected, but the contract went back to tender in favour of something a couple of million pounds cheaper, and you have to ask, why was it so much cheaper? If you keep going lower, you find people who cut corners. All the way through, building control has been privatised.”