Celotex is challenging claims made in a BBC News story that it knowingly mis-sold the dangerously flammable insulation used on Grenfell Tower.

In Monday’s episode of Panorama, the BBC claimed that Celotex had used extra fire-retardant in the cladding material which was safety tested, but then swapped it for a cheaper, more flammable version which was used on Grenfell Tower.

Celotex denies this claim. On its website, it states: “During the programme a new allegation was made that Celotex had added fire retardant to the formula of a product sample which was used for a safety certificate and that a different product to this was actually sold. Prior to Panorama raising this, we were unaware of this allegation and had not identified anything which would support it. Celotex is investigating this allegation via all avenues as a matter of urgency.”

The product is PIR rigid board insulation RS5000. When this it heats up, its plastic centre melts and burns, immediately setting fire to the insulation. This material caused the fire to spread quickly up Grenfell Tower and release a toxic smoke. The BBC claims that while the manufacturers of both the cladding and the insulation both knew the materials were being combined on Grenfell Tower, the combination was never tested for use on tower block buildings, and neither company warned the project of the potential danger. The product is used on hundreds of other buildings all over the country.

The BBC claims Celotex specifically reached out to the Grenfell Tower refurbishment project in 2014 to sell their insulation. It asserts that Celotex told the refurbishment project that its insulation was suitable for buildings over 18m in height, and that it was suitable for use with a range of cladding panels, when this was untrue. The documentary goes on to claim that Celotex was warned that its marketing for the product was misleading, but continued anyway. The BBC say this could amount to corporate manslaughter.

In this May issue of Builders’ Merchants News it was reported that Celotex is a core participant in the public inquiry, which began on 21 May. In a statement on its website, Celotex says that it is cooperating with the police and the inquiry. It maintains: “Celotex has not used any special formulation for the recent successful BS-8414 system test in May 2018 or Class 0 fire testing. It is very hard to understand the Panorama allegation alongside those tests.

“The company has been conducting a detailed review of the way RS5000 was tested and marketed. The current management team has only recently determined that there were differences between the system as tested for BS 8414:2 and the description of that system in the report of the test. These differences were carried through into our marketing of RS5000. Our priority is to establish whether there are any safety issues arising from these differences.”

Notably, in June 2017 Celotex withdrew RS5000 from sale, despite claiming it had passed fire safety tests. The suspension of RS5000 remains in place today.