Grenfell Tower was covered in flammable materials because of “systematic dishonesty” from those who made and sold cladding and insulation, the final report has concluded.

Here is a summary of the main firms and what the inquiry into the disaster said about them:

Arconic Architectural Products made and sold the Reynobond 55 cladding panels with a polyethylene (PE) core which were used in the refurbishment of Grenfell Tower and were later found to have fuelled the blaze.

The phase one report in 2019 concluded the ‘principal reason’ the flames shot up the building at such speed was the combustible cladding, which acted as a ‘source of fuel’.

The final report noted that polyethylene ‘burns fiercely’ and, when used in cassette form (as in three-dimensional structures), the Reynobond 55 PE was ‘extremely dangerous’.

The phase two report stated that, from 2005 until after the Grenfell Tower fire, Arconic ‘deliberately concealed from the market the true extent of the danger of using Reynobond 55 in cassette form, particularly on high-rise buildings’.

Responding to the inquiry, Arconic said it was its subsidiary, Arconic Architectural Products SAS (AAP), which had supplied the material used for cladding in the tower’s refurbishment, and that it rejects ‘any claim that AAP sold an unsafe product’ and ‘did not conceal information from or mislead any certification body, customer, or the public’.

Celotex was the manufacturer of the majority of the insulation boards used in the refurbishment.

Its Rs5000 was one of the insulation components used in the Grenfell Tower rainscreen cladding system and its TB4000 insulation was used to fill gaps in the window surrounds during the refurbishment of the tower.

The inquiry’s final report concluded that it had ’embarked on a dishonest scheme to mislead its customers and the wider market’ in an attempt to break into a market which had been dominated by Kingspan.

In its response, Celotex said it had ‘reviewed and improved process controls, quality management and the approach to marketing within the Celotex business to meet industry best practice’.

The company has long said its K15 insulation product made up 5% of the insulation in the tower block and was used without its knowledge.

But the report found that Kingspan ‘knowingly created a false market in insulation’ from 2005 onwards for use on buildings over 18 metres tall by claiming its K15 product had been part of a system that had been successfully tested under the BS 8414 cladding fire safety test, meaning it could be used in the wall of any building of that height regardless of its design or other components.

Responding to the report, Kingspan said it had ‘long acknowledged the wholly unacceptable historical failings that occurred in part of our UK insulation business’ but said these were ‘in no way reflective of how we conduct ourselves as a group, then or now’.

Rydon was appointed in 2014 as the design and build contractor for the refurbishment of Grenfell Tower.

Along with architect Studio E it was deemed to have taken ‘a casual approach to contractual relations’.

The report found Rydon was ‘ill-equipped to oversee the work of its sub-contractors and consultants’ and that the firm and others appeared to have ‘assumed that someone else was, or should be, taking responsibility for critical decisions, such as the choice of insulation, rainscreen panels and other materials’.

Architect Studio E was responsible for the design of the external wall and the choice of materials used in the construction.

Its ‘failure to recognise’ the ACM (aluminium composite material) was dangerous and to warn the tenant management organisation (TMO) against using it ‘represented a failure to act in accordance with the standard of a reasonably competent architect’.

Its failure also to recognise that the Celotex insulation was combustible and unsuitable for use in a high-rise meant it ‘bears a very significant degree of responsibility for the disaster’.

The Building Research Establishment had, the report noted, held a trusted position within the construction industry and was recognised both nationally and internationally as a leader in fire safety.

But it added: ‘However, from 1991 much of the work it carried out in relation to testing the fire safety of external walls was marred by unprofessional conduct, inadequate practices, a lack of effective oversight, poor reporting and a lack of scientific rigour.’

It had been a government agency providing independent advice and information on building performance, construction and fire safety in the UK, before it was privatised in 1997.

The report said that in some cases there was ‘evidence of a desire to accommodate existing customers and to retain its status within the industry at the expense of maintaining the rigour of its processes and considerations of public safety’.

Exova provided fire safety advice to Kensington and Chelsea Tenant Management Organisation (KCTMO) for the proposed tower refurbishment.

The final report found that Exova ‘bears considerable responsibility for the fact that Grenfell Tower was in a dangerous condition on completion of the refurbishment’.

The ‘most serious criticism’ it said, was that Exova ‘failed to produce a final version of the fire safety strategy’ for the refurbished building and had ‘failed’ to warn the design team about the potential consequences of that.