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The rain-screen cladding, typically made from wood, metal or plastic, used on the side of the residential tower in west London may have helped the massive fire to spread through all 24 storeys within minutes, according to some experts.
The Grenfell Tower, originally built in 1974, was refurbished last year with improvements including rain-screen cladding, which is used to improve thermal insulation and modernise the exterior of the building.
Rydon Construction, the company behind the refurbishment in 2016, has claimed the work it carried out met all fire safety standards.
A Rydon statement read: "We are shocked to read of the devastating fire at Grenfell Tower and our immediate thoughts are with those that have been affected by the incident, their families, relatives and friends.
"Rydon completed a refurbishment of the building in the summer of 2016 for Kensington and Chelsea Tenant Management Organisation (KCTMO) on behalf of the Council, which met all required building control fire regulation and health and safety standards.
"We will cooperate with the relevant authorities and emergency services and fully support their enquiries into the causes of this fire at the appropriate time."
The trigger for the fire has been attributed to a faulty fridge on one of the lower floors - the third or fourth floor - however some eyewitnesses also reported seeing blue flames which could indicate a gas explosion.
After the fire broke out it should have beencontained to a few flats as per modern building norms in the UK.
Butthe speed at which it engulfed the entire tower block is being attributed to the building'scladding, which is a material that is usually attached directly to the frame of a building to act as an outer wall.
Typically made from wood, metal, plastic, masonry or a range of materials, it is applied to prevent condensation and allow water vapour to escape.
Rain-screen cladding is a double-wall construction that makes use of a surface to keep the rain out.
It also has an inner layer that offers thermal insulation, prevents excessive air leakage and carries wind loading.
Grenfell Tower was fitted with zinc rain-screen cladding and glazed curtain walling after the 10-million-pounds refurbishment last year.
Sliding windows were replaced with double glazing in the 120 flats to prevent people falling.
"The materials that sit behind the claddings should be of non-combustible material.
I wonder if someone has taken advice from the experts, someone with qualifications,"saidfire safety expert Graham Fieldhouse, who fears the external spread of the fire at Grenfell may have been caused by the rain-screen cladding.
The local Grenfell Action Group had long claimed that the building, housing around 600 residents, was unsafe.
After the fire today, the group said: "All our warnings fell on deaf ears and we predicted that a catastrophe like this was inevitable and just a matter of time.
"So far six people have been confirmed as fatalities in the fire, a figure that is expected to rise as firefighters complete their search and rescue.
Commander Stuart Cundy, of the Metropolitan Police, said the recovery operation would be "complex and lengthy", and the number of fatalities was expected to rise.
As many as 74 people have been treated for injuries in hospitals and hundreds remain in community centres across west Londonas nearby buildings wereevacuated as a precaution.
Fire Commissioner Dany Cotton said hundreds of firefighters expected to be on the scene for at least another 24 hours and she would not speculate about the cause of the blaze at this stage.
"This is an unprecedented incident. In my 29 years of being a firefighter, I have never ever seen anything of this scale,"she said.
A structural engineer continues to monitor the stability of the building and has ruled that it is not in danger of collapse and that rescue teams are safe to be inside to carry on the rescue work.
Initially, it was feared that the building, which appears to be gutted, could collapse.