As the inquiry is halted until 11 January, because of a covid-19 positive and Christmas holidays, we revisit the evidence that has emerged so far in the second module of the hearing, which has put the spotlight on product manufacturers

Grenfell Tower wrapped


Grenfell Tower

Grenfell Tower insulation manufacturer Celotex was “completely unethical” in its bid to present a product as suitable for use on high-rise buildings and tap rival firm Kingspan’s multimillion-pound market, the probe into 2017’s disaster has heard.

The latest hearings of the Grenfell Tower Inquiry into the fire, which claimed 72 lives, is examining the products used to overclad the west London block as part of its flawed refurbishment, which resulted in a structure that actively promoted the spread of fire (see “What fuelled the fire”, below).

Former staff at Celotex, which was bought by French multinational Saint-Gobain in 2012, told the inquiry the firm set its sights on Kingspan’s “£10m-a-year market” for products for use as part of rainscreen cladding systems on high-rise buildings. Celotex did not have a product to compete with Kingspan’s Kooltherm K15. It decided to rebrand its FR5000 polyisocyanurate (PIR) insulation as RS5000 and secure certification for use above 18m. 

Meanwhile Kingspan, which describes itself as the “global leader in high-performance insulation”, was marketing its Kooltherm K15 phenolic insulation with the aid of BRE fire-test reports that it now accepts were “not sufficiently representative” of the product being sold.

I went along with a lot of actions at Celotex that, looking back on reflection, were completely unethical

Jonathan Roper, ex-product manager, Celotex

The inquiry heard that Celotex’s FR5000 insulation failed a February 2014 BS 8414 fire test intended to demonstrate its suitability for use on high-rise buildings. In May the same year the same product, rebranded as RS5000, passed a fire test as part of a rainscreen cladding rig using Marley Eternit cement panels.  However, the rig also included a non-combustible magnesium oxide board to improve the system’s overall performance. 

What fuelled the fire

The inquiry’s phase one report found that fire spread so rapidly around the block primarily because the polyethylene cores of the Reynobond aluminium composite material (ACM) panels attached to the tower as part of its refurbishment “acted as a source of fuel”. It said polyisocyanurate (PIR) and phenolic foam insulation boards behind the ACM “contributed to the rate and extent of vertical flame spread”; components of the window surrounds, manufactured by Celotex and Kingspan, were also thought to have aided the spread of fire.

Celotex FR5000 PIR insulation was proposed for Grenfell in 2012 and included on the National Building Specification for the project. Celotex RS5000 was the main insulation installed behind the ACM panels. It was the same product as FR5000, which had failed a test in 2014.

Kingspan’s combustible Kooltherm K15 insulation was never specified for the project but installed when RS5000 was not available. Kingspan said the quantity of K15 used for the refurbishment was just 5% of the total for the project, when measured by area.

RS5000 was then marketed as a new product. Promotional material said it was “the first PIR board to successfully test to BS 8414-2” and specified that the result applied to the system that was tested. No mention was made of the 6mm magnesium-oxide boards.

Jonathan Roper, who was product manager for RS5000 at Celotex, told the inquiry the firm’s efforts to conceal the precise system that passed the BRE test sat “very uncomfortably” with him and agreed it had been “dishonest”.

He added: “I went along with a lot of actions at Celotex that, looking back on reflection, were completely unethical. I probably didn’t potentially consider the impact at the time. I was 22, 23, first job. I thought this was standard practice.”

Roper left the firm in 2016. His former colleague Deborah Berger told the inquiry that she had been so shocked at Celotex’s rigging of the RS5000 test she wrote “WTF?” – short for “what the fuck?” – in the margin of her copy of the test report where the magnesium oxide panels were mentioned.

I thought Celotex prided itself on doing the right thing, being honest, and I was really shocked by this

Debbie Berger, ex-staff member, Celotex

Even though it was unsuitable for use on high-rise buildings, Celotex FR5000 was suggested for use as part of the tower refurbishment by a consultant at Max Fordham in 2012. Project architect Studio E never probed the suggestion. Cladding subcontractor Harley Facades said it had been assured by Celotex that RS5000 was suitable.

Kingspan K15 was never specified for use as part of the cladding system for Grenfell Tower, but the product was used when RS5000 was not available. Kingspan estimates that K15 accounted for about 5% of the insulation used as part of the cladding system.

A look back at module one: How experts blamed key players for ‘shambles’

Nevertheless, the inquiry heard damning information about Kingspan’s efforts to ensure that combustible K15 insulation continued to be considered acceptable for use on high-rise buildings despite changes to the product’s composition that caused a “raging inferno” in a 2007 BRE test. It also heard a 2014 fire-test pass used to support the use of K15 was secured with a trial version of a new formulation for the product that was never sold. 

I can’t remember any real sort of shock. I don’t think they were concerned in the same way as me

Ivor Meredith ex-product manager, Kingspan

Ivor Meredith, a former Kingspan project manager, said it had been common knowledge in the firm that test data used to support K15 had been from the “old technology” version. He told the inquiry he sent his managers an animated email about “new technology” K15’s dramatic 2007 test failure. “I can’t remember any real sort of shock,” he said. “I don’t think they were concerned in the same way as me.”

One of Meredith’s managers was Philip Heath, who still works for Kingspan. The inquiry heard that he sent an internal email in 2008 saying facades specialist Wintech “can go f’#ck themselves, and if they are not careful we’ll sue the a’#se of them” when the firm raised concerns about K15’s suitability for high-rise use.

Other firms raising concerns about the evidence base for K15’s use included Bowmer & Kirkland, Lakesmere, Astec Projects and Kingspan Group sister company Kingspan Off-Site. The National House Building Council also voiced significant concerns before an about-turn in 2016. 

Wintech can go f’#ck themselves, and if they are not careful we’ll sue the a’#se of them

An internal email written by Philip Heath, technical manager, Kingspan, after Wintech queried use of K15

Kingspan’s Phase 2, Module 2 opening statement to the inquiry says post-fire testing conducted on behalf of the Department for Communities and Local Government showed flames spread rapidly across Reynobond PE 55 ACM panels even when they were backed with non-combustible insulation. “This is a clear indicator that any PE-cored ACM cladding system would have been unsafe on Grenfell Tower, regardless of insulation type,” it said.

Celotex said its marketing literature for RS5000 clearly stated the basis on which the product was acceptable for use on buildings above 18m in height, but no member of the refurbishment project team paid proper regard to the document.

Like Kingspan, Celotex says the team’s failure to consider the fire performance of ACM panels was the “particularly notable” issue. 

The inquiry continues.

Product timelines: What happened when


2005 “Old technology” K15 passes BS 8414 fire test conducted by BRE. Kingspan withdraws this test report in October 2020.

2007 “New technology” K15 fails  BRE fire test spectacularly. 

2009 Local Authority Building Control approves K15 for use on buildings above 18m.

2014 Trial formulation of K15 with new blowing agent passes BS 8414 test, but product is never sold.

2015 National House Building Council raises concerns about Kingspan’s ability to evidence safety of K15. Threatened with legal action.

2016 NHBC issues technical note backing K15 (and Celotex RS5000) as acceptable for use as part of ACM cladding systems on buildings above 18m in height.

2020 Kingspan “withdraws” three BRE BS 8414 fire test reports for K15 (one from 2005 and two from 2014) on grounds they used versions of K15 that were “not sufficiently representative” of  product currently sold. 


2012 Consultant at Max Fordham proposes Celotex FR5000 as  suitable insulation for Grenfell refurbishment to architect Studio E. Recommendation made because of thermal efficiency and thinness, rather than appropriateness for high-rise buildings. 

2013 FR5000 included on  National Building Specification for Grenfell refurbishment, which forms part of tender pack for prospective main contractors. 

2014 Celotex FR5000 branded as “RS5000” and passes BS 8414 test conducted by BRE in a rig that includes Marley Eternit concrete rainscreen cladding. Presence of  magnesium oxide panel that improves system’s fire performance is concealed.

2016 NHBC issues technical note backing RS5000 (and Kooltherm K15) as acceptable for use as part of ACM cladding systems on buildings above 18m in height.

2017 Celotex suspends supply of RS5000 on 23 June, nine days after the Grenfell Tower fire.

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