When the building was renovated, the materials used for the outside of the building were changed.
Fire safety experts have speculated that this new material was a possible cause of the rapid spread of the fire.
They said it essentially worked like a chimney in spreading the fire.
The material could be seen burning and melting, causing additional speculation that it was not fire resistant.
One resident said, "The whole one side of the building was on fire.
The cladding went up like a matchstick."

Records show that a contractor installed "over-cladding with ACM cassette rain screen" during the recent refurbishment at Grenfell Tower.
The term ACM stands for aluminium composite material.
With this kind of material, the choice of insulation core material determines how easily it can be burned.
Several tower building fires have involved the same external materials, including the 2009 Lakanal House fire in Camberwell, London, the 2009 Beijing Television Cultural Center fire and the 2015 fire at The Marina Torch, Dubai.
Sam Webb, the architect who investigated the Lakanal fire and who sits on the All Party Parliamentary Fire Safety & Rescue Group, said "This tragedy was entirely predictable, sadly."

The product used was Reynobond, which is available with different types of core material—polyethylene, as reportedly used in Grenfell Tower (Reynobond PE), or a more fire-resistant material (Reynobond FR).
The Reynobond cladding reportedly cost £24 per square metre for the fireproof versions, and £22 for the flammable version.
According to the BBC, the more fire-resistant version (Reynobond FR) is a very new product, and it is unclear whether it was available at the time the building was being clad.

According to the US-based manufacturer of Reynobond, the polyethylene version of the material is banned in the United States for use in buildings exceeding 40 feet (12 m) in height, because of the risk of spreading fire and smoke.
The refurbishment also used an insulation foam product named Celotex RS5000, installed behind the cladding.

According to its datasheet, the polyisocyanurate 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".

The cladding at Grenfell seems to have been used to decorate other apartment blocks.
People are concerned that the affected buildings may face the same problems.

Some residents had reported concern that the new cladding on the building was fixed onto it with wooden battens.
There is widespread concern amongst residents and fire safety experts about the increasing use of timber, even in high-rise buildings, following a change to building regulations.
It was reported that one reason for the new cladding was to improve the view for people living in the surrounding area.
When the building was renovated, the materials used for the outside of the building were changed. Fire safety experts have speculated that this new material was a possible cause of the rapid spread of the fire. They said it essentially worked like a chimney in spreading the fire. The material could be seen burning and melting, causing additional speculation that it was not fire resistant. One resident said, "The whole one side of the building was on fire. The cladding went up like a matchstick."
Records show that a contractor installed "over-cladding with ACM cassette rain screen" during the recent refurbishment at Grenfell Tower. The term ACM stands for aluminium composite material. With this kind of material, the choice of insulation core material determines how easily it can be burned. Several tower building fires have involved the same external materials, including the 2009 Lakanal House fire in Camberwell, London, the 2009 Beijing Television Cultural Center fire and the 2015 fire at The Marina Torch, Dubai. Sam Webb, the architect who investigated the Lakanal fire and who sits on the All Party Parliamentary Fire Safety & Rescue Group, said "This tragedy was entirely predictable, sadly."
The product used was Reynobond, which is available with different types of core material—polyethylene, as reportedly used in Grenfell Tower (Reynobond PE), or a more fire-resistant material (Reynobond FR). The Reynobond cladding reportedly cost £24 per square metre for the fireproof versions, and £22 for the flammable version. According to the BBC, the more fire-resistant version (Reynobond FR) is a very new product, and it is unclear whether it was available at the time the building was being clad.
According to the US-based manufacturer of Reynobond, the polyethylene version of the material is banned in the United States for use in buildings exceeding 40 feet (12 m) in height, because of the risk of spreading fire and smoke. The refurbishment also used an insulation foam product named Celotex RS5000, installed behind the cladding.
According to its datasheet, the polyisocyanurate 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".
The cladding at Grenfell seems to have been used to decorate other apartment blocks. People are concerned that the affected buildings may face the same problems.
Some residents had reported concern that the new cladding on the building was fixed onto it with wooden battens. There is widespread concern amongst residents and fire safety experts about the increasing use of timber, even in high-rise buildings, following a change to building regulations. It was reported that one reason for the new cladding was to improve the view for people living in the surrounding area.
Grenfell Tower fire