Fire safety experts have said that the building's new external cladding was a possible cause of the rapid spread of the fire.
Experts said the gap between the cladding and the insulation worked like a chimney to spread the fire.
The cladding could be seen burning and melting, causing additional speculation that it was not made of fire-resistant material.
One resident said: "The whole one side of the building was on fire.
The cladding went up like a matchstick."

Concerns about the dangers of external cladding were raised years before, following a fire in 1991 at flats in Knowsley Heights, Merseyside.
Recent major high-rise fires that have involved flammable cladding are listed below.

Records show that a contractor had been paid £2.6 million to install an "ACM rainscreen over-clad" during the recent refurbishment at Grenfell Tower.
ACM stands for "aluminium composite material", also known as a sandwich panel, the combustibility of which depends on the choice of insulation core material.

One of the products used was Arconic's 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 fire-retardant version, and £22 for the combustible version.

According to Arconic's website and brochure for the mainland European market at the time of the fire, the Reynobond PE cladding used was suitable only for buildings 10 metres or less tall; the fire-retardant Reynobond FR was suitable for buildings up to 30 metres tall; and above the latter height, such as the upper parts of Grenfell Tower, the non-combustible A2 version was supposed to be used ("As soon as the building is higher than the firefighters' ladders, it has to be conceived with an incombustible material").
After the fire, Arconic stopped sales of Reynobond PE worldwide for tower blocks.

Similar cladding containing highly flammable insulation material is believed to have been installed on thousands of other high-rise buildings in countries including Britain, France, the UAE and Australia.
Advice published by the Centre for Window and Cladding Technology is that where such materials are used in buildings over 18m, the fire performance of the cladding system as a whole must be proven by testing.

In September 2014, a building regulations notice for the re-cladding work was submitted to the authority and marked with a status of "Completed—not approved".
The use of a "Building Notice" building control application is used to remove the need to submit detailed plans and proposals to a building control inspector in advance, where the works performed will be approved by the inspector during the course of their construction.
Building inspector Geoff Wilkinson remarked that this type of application is "wholly inappropriate for large complex buildings and should only be used on small, simple domestic buildings".

On 18 June, Chancellor of the Exchequer Philip Hammond stated that the cladding used on Grenfell Tower was banned in the United Kingdom.
Grenfell Tower was inspected 16 times while the cladding was being put on but none of these inspections noticed that materials effectively banned in tall buildings were being used.
Judith Blakeman, local Labour councillor questioned the competence of the inspectors.
Blakeman, representing the Grenfell residents, said, "This raises the question of whether the building regulations officers were sufficiently competent and did they know what they were looking at.
It also begs a question about what they were actually shown.
Was anything concealed from them?"

The Department for Communities and Local Government stated that cladding with a polyethylene core "would be non-compliant with current Building Regulations guidance.
This material should not be used as cladding on buildings over 18 metres (59 ft) in height."
On 31 July 2017, the Department released results of fire safety testing on the cladding panels used at Grenfell Tower, which were carried out by the B
Fire safety experts have said that the building's new external cladding was a possible cause of the rapid spread of the fire. Experts said the gap between the cladding and the insulation worked like a chimney to spread the fire. The cladding could be seen burning and melting, causing additional speculation that it was not made of fire-resistant material. One resident said: "The whole one side of the building was on fire. The cladding went up like a matchstick."
Concerns about the dangers of external cladding were raised years before, following a fire in 1991 at flats in Knowsley Heights, Merseyside. Recent major high-rise fires that have involved flammable cladding are listed below.
Records show that a contractor had been paid £2.6 million to install an "ACM rainscreen over-clad" during the recent refurbishment at Grenfell Tower. ACM stands for "aluminium composite material", also known as a sandwich panel, the combustibility of which depends on the choice of insulation core material.
One of the products used was Arconic's 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 fire-retardant version, and £22 for the combustible version.
According to Arconic's website and brochure for the mainland European market at the time of the fire, the Reynobond PE cladding used was suitable only for buildings 10 metres or less tall; the fire-retardant Reynobond FR was suitable for buildings up to 30 metres tall; and above the latter height, such as the upper parts of Grenfell Tower, the non-combustible A2 version was supposed to be used ("As soon as the building is higher than the firefighters' ladders, it has to be conceived with an incombustible material"). After the fire, Arconic stopped sales of Reynobond PE worldwide for tower blocks.
Similar cladding containing highly flammable insulation material is believed to have been installed on thousands of other high-rise buildings in countries including Britain, France, the UAE and Australia. Advice published by the Centre for Window and Cladding Technology is that where such materials are used in buildings over 18m, the fire performance of the cladding system as a whole must be proven by testing.
In September 2014, a building regulations notice for the re-cladding work was submitted to the authority and marked with a status of "Completed—not approved". The use of a "Building Notice" building control application is used to remove the need to submit detailed plans and proposals to a building control inspector in advance, where the works performed will be approved by the inspector during the course of their construction. Building inspector Geoff Wilkinson remarked that this type of application is "wholly inappropriate for large complex buildings and should only be used on small, simple domestic buildings".
On 18 June, Chancellor of the Exchequer Philip Hammond stated that the cladding used on Grenfell Tower was banned in the United Kingdom. Grenfell Tower was inspected 16 times while the cladding was being put on but none of these inspections noticed that materials effectively banned in tall buildings were being used. Judith Blakeman, local Labour councillor questioned the competence of the inspectors. Blakeman, representing the Grenfell residents, said, "This raises the question of whether the building regulations officers were sufficiently competent and did they know what they were looking at. It also begs a question about what they were actually shown. Was anything concealed from them?"
The Department for Communities and Local Government stated that cladding with a polyethylene core "would be non-compliant with current Building Regulations guidance. This material should not be used as cladding on buildings over 18 metres (59 ft) in height." On 31 July 2017, the Department released results of fire safety testing on the cladding panels used at Grenfell Tower, which were carried out by the B
Grenfell Tower fire