The refurbishment also used an insulation foam product named Celotex RS5000, installed behind the cladding.
Police said this insulation proved "more flammable than the cladding".

According to its datasheet, the polyisocyanurate (PIR) product—charred pieces of which littered the area around Grenfell Tower after the fire—"will burn if exposed to a fire of sufficient heat and intensity".
PIR insulation foams "will, when ignited, burn rapidly and produce intense heat, dense smoke and gases which are irritating, flammable and/or toxic", among them carbon monoxide and hydrogen cyanide.
The fire toxicity of polyisocyanurate foams has been well understood for some time.

At least three survivors were treated for cyanide poisoning.
Simultaneous exposure to carbon monoxide and hydrogen cyanide  is more lethal than exposure to the gases separately.

Celotex's Rainscreen Compliance Guide, when specifying Celotex RS5000 in buildings above 18 metres (59 ft), sets out the conditions under which the product was tested and for which it has been certified as meeting the required fire safety standards.
These include the use of (non-combustible) 12 mm fibre cement rainscreen panels, ventilated horizontal fire breaks at each floor slab edge and vertical non-ventilated fire breaks.
It states that any changes from the tested configuration "will need to be considered by the building designer".
The refurbishment also used an insulation foam product named Celotex RS5000, installed behind the cladding. Police said this insulation proved "more flammable than the cladding".
According to its datasheet, the polyisocyanurate (PIR) product—charred pieces of which littered the area around Grenfell Tower after the fire—"will burn if exposed to a fire of sufficient heat and intensity". PIR insulation foams "will, when ignited, burn rapidly and produce intense heat, dense smoke and gases which are irritating, flammable and/or toxic", among them carbon monoxide and hydrogen cyanide. The fire toxicity of polyisocyanurate foams has been well understood for some time.
At least three survivors were treated for cyanide poisoning. Simultaneous exposure to carbon monoxide and hydrogen cyanide  is more lethal than exposure to the gases separately.
Celotex's Rainscreen Compliance Guide, when specifying Celotex RS5000 in buildings above 18 metres (59 ft), sets out the conditions under which the product was tested and for which it has been certified as meeting the required fire safety standards. These include the use of (non-combustible) 12 mm fibre cement rainscreen panels, ventilated horizontal fire breaks at each floor slab edge and vertical non-ventilated fire breaks. It states that any changes from the tested configuration "will need to be considered by the building designer".
Grenfell Tower fire