Thread by @PeteApps

Lunchtime update from the Grenfell Tower Inquiry:

Dr Malcolm Rochefort grilled over why Kingspan's insulation was not withdrawn from the market after tests showed a deteriorating fire performance

Much of this evidence has already been discussed over the last two weeks, but the inquiry has been asking Rochefort about the change in way of making its flagship insulation for high rises, K15, in 2006 and subsequent testing of that material

(Your regular reminder that a small quantity of K15 was used on Grenfell, but the product has been sold and installed for high rises for 15 years and is on hundreds, possibly thousands)

In 2005, Kingspan passed a large scale test with K15 and began marketing as suitable for use on high rises, but then changed its processes to make the product cheaper to produce and more thermally efficienct and began selling the new product from 2006.

Among these changes were a chemical change which retained the blowing agent in the product and perforations to the foil facing to help dry it out. (Rochefort was aware of this second factor but did not reference it in his witness statement - he said an oversight)

Docs show the fire checks were still not completed by 2008. So why had it been on the market for two years?

"It's about life safety, this isn't about appearance or thermal conductivity. Did it not occur to you that it was a very unwise move to be selling [it]?"

Rochefort says: It had the European classification, but I take your point about the [large scale test]."

But when a fresh large scale test (with solid aluminium cladding) was carried out in December 2007, the system failed dramatically. An internal Kingspan report said: "The new technology K15 is very different in a fire situation to the old technology"

It added that the insulation now "burnt very ferociously" and continued to burn when fire source was extinguished. It suggested removing the perforations and adding a fire retardant. Neither was done. Why not?

"If I remember correctly, there were a number of other 8414 tests planned so the plan was to see if we got the same fire performance... because it was distinctly possible that it might be the system that was the cause."

"Did you give any consideration to stopping the sale of K15, at least above 18m?"

Says he was concerned and did consider going back to old technology after further tests in April (was never done)

He is also asked about how the product achieved Class 0 (a two part test, which it was advertised as achieving). It could not pass, so Kingspan separated the insulation foam from the foil facing and tested them separately for each of the two parts.

"My understanding is that was an appropriate way of passing the [Class 0 test]. It's why it was used."

Then we see an internal report from April that shows the product has demonstrated a faster time to ignition and double the heat release in specific tests on the product. Report said improving this was "required to maintain our position in the high rise facade market"

Then there was an internal debate with Kingspan Offsite (another wing of the business which did not know about the product change) which also failed tests and wanted to know why

Emails show Rochefort suggesting sending them old technology K15 instead. He claims in evidence that he was suggesting replacing the new tech with old for the entire market. QC says "a much more natural reading" of his email is that he was just going to use it for testing.

Rochefort carries on after lunch.