Chartered Institute of Building Magazine of the Chartered Institute of Building


Grenfell: Contractors queried suitability of Kingspan insulation over 18m

4 December 2020
Tony Millichap

Contractors questioned the suitability of Kingspan’s K15 insulation, a quantity of which was used on the refurbishment of Grenfell Tower, for use in buildings above 18m in a series of queries made before the disaster, the Grenfell Tower Inquiry has heard.

During evidence from former technical manager Tony Millichap, who had responsibility for K15 from 2010 until 2015, the Inquiry heard how contractor Astec Projects, now in administration, questioned the suitability of K15 in November 2013 for a project it was working on called Hampton House.

The firm was considering using K15 behind the façade cladding for the 15-storey building and asked Kingspan to review detailed drawings and asked it to confirm its ability to comply with a U-value.

Kingspan replied: “There are quite a few comments we would offer in regard to these proposed build-ups. For the steel frame wall types: although cement boards of the type described can be (and are) excellent fire performers and could withstand temperatures in the BS 8414 test…our current testing to that standard is limited to a fully combustible substrate.

“Therefore we have shown a non-com [non-combustible] calcium silicate board as the sheathing.”

The response from Kingspan prompted Simon Hepworth, a senior designer at Astec Projects, to reply: “Your email would indicate it is still Kingspan’s view that K15 is fit-for-purpose over 18m. Is this the case?

“You have talked about non-combustible substrates yet, the main points of contention with regard to your 8414 testing is that it was based on block work substrate not [steel-framed structure] with a sealed cementitious outer cladding. Neither of these conditions even remotely resemble what the proposed construction is here and you know it is the BRE’s view that the use of K15 should not be specified on the basis of those test results.”

Hepworth added: “Further, the project in question is for the same client, who are using the same consultants as our Riverlight project, where the substantiation of K15 use still remains unresolved after many months of extremely difficult negotiations.

“Kingspan seem to have lost interest in this issue pending results of the upcoming 8414-2 test…I realise a lot hinges on the results of next week’s 8414-2 test , but ask what is Kingspan going to do if it fails?

“Where does that leave us with Riverlight? What is your position with regard to this should we have to start stripping cladding off an 18-storey building?… With the above in mind we find it incredible you have any comfort in proposing K15 on this project, or in fact any other over 18m.

“This does, in my mind bring your corporate responsibility into question. You will no doubt take the view that we, as the envelope contractor have to take responsibility for the design and specification of the façade materials and you are simply an insulation supplier, yet here we are with you endorsing your product knowing it is not appropriately tested, with little way of substantiating it is fit for purpose for this project in any way whatsoever.”

Responding in the hearing to the Hepworth’s emails, Millichap said: “It does point towards an issue whereby they [Astec Projects] have gone a very long way down the line in adopting this product without it being signed off prior to building the building. This is installing a solution and then trying to get it ratified retrospectively. Surely he should have done his homework before we found ourselves in this position where we’re being held to try and support the project.

“I’m not suggesting that that isn’t something that we weren’t trying to do. But there does come a point whereby, as I said , if they don’t agree with the advice and the opinion that we’ve given in respect of their project , then, absolutely, K15 shouldn’t have been installed.”

Kate Grange QC asked: “But wasn’t it on the back of Kingspan’s endorsement of their product that they installed it in the first place?”

Millichap said: “As I said, they’ve stated themselves in the email that they are the envelope contractor and that it is their responsibility.”

Lakesmere complaint

Meanwhile, the Inquiry also heard about a complaint made by cladding and roofing contractor Lakesmere (which fell into administration in 2017) about K15. Stuart Harris from Lakesmere emailed Kingspan in May 2014 regarding a project called First Street North in Manchester having taken advice from Arup about the compliance of K15 for use on that project.

Harris said: “In simple terms K15 100mm is not compliant with Building Regs for use in buildings over 18m, because it has not been tested in accordance with BR135/BS 8414-1 2002. As a result we’re now having to remove the three floors of insulation and fire barriers that we have currently installed, and replace it all with mineral wool insulation and new fire barriers to the entire complex. Not a good way to end the week.”  

Kingspan agreed to issue a £20,000 credit note for the insulation.

In his witness statement, Millichap did not mention being aware prior to May 2015 of any concerns raised in respect of K15. Asked by Grange why he had not mentioned the complaints from Astec Projects and Lakesmere, Millichap said: “I wouldn’t have been able to recall them at the time I did this. I didn’t have time to do as extensive review of the documents I was supplied prior to writing the statement.”

The Inquiry continues.