Reading through the 2012 Planning and Permit drawings at The Royal Borough of Kensington and Chelsea website link that Ingenuity provided, it appears that during the planning & public comment stage there was a contractor, Leadbitter originally designated as the assigned builder. Also the original cladding system was presented to the tenants as VMZ Composite with a FR mineral-rich polyethylene core. In finalizing the project, Leadbitter was over the budget by over a million British Pounds, so the Royal Borough of Kensington and Chelsea decided to put the project out to public bid. As near as I can tell there doesn't appear to have been a set of Specifications to accompany the drawings offered to bidders by The Royal Borough of Kensington and Chelsea & issued by the Architect. I'm thinking the proposals submitted by Facade & Curtain-wall contractors are open to whatever particular brand of cladding they feel meets the goals and which they are accustom to working with. I have read on the internet that in the UK, even if there wasn't an particular level of Fire Resistance specified, in the UK it does not absolve the responsible parties from insuring the proper safety standard is met. Under the law, if you undertake to perform the work you are obligated to know the standards. So the facade contractor, the general contractor, the TMO/property management are all on the hook. The Local Planning Authority also seems to be on the hook. In the Decision paper by the Town Planner authorizing the work, it states:
Detailed drawings or samples of materials as appropriate, in respect of the
following, shall be submitted to and approved in writing by the Local
Planning Authority before the relevant part of the work is begun and the
works shall not be carried out other than in accordance with the details so
approved and shall thereafter be so maintained:
·
Materials to be used on the external faces of the building(s)
The building had a problem with heat buildup in the summer and the center pivot windows were chosen to assist with air exchange but may have created a convection effect. Apparently the floor to window height of the existing concrete spandrel panels was too low & presented a risk of falling, if one were to lean to far out the window. That might explain the odd section drawing LittleInch posted. Having lived in a building with poor air turnover, it would not surprise me if some tenants left the front doors open to facilitate a better draft, exacerbating the updraft once the fire got going. How many left the door to their unit open when they fled?
UK refrigerators have Isobutane refrigerant as a replacement for Freon. Pre-2010 Isobutane Exploding refrigerators are a real possibility. Some of the evacuees reported seeing blue flames and hearing explosions as they fled. It seems refrigerator explosions occur most often at night, after the refrigerator door has been closed for an extended time.
The facade supplier appears to be OMNIS. While Reynobond PE is the suspected culprit. OMNIS produces & supplies more than one brand of ACM. They have removed their ACM .pdf spec sheet from their website. OMNIS had bought out Rigidal while it was under reorganization; right about the time the facade contractor, Harley was the low bidder...,
The Celotex type insulation doesn't strike me as the overwhelming fuel component. Much of the charred insulation remains in place on the spandral panels and large lightly scorched pieces of it are on the ground where they came away from the columns. It is the ACM low density polyethylene LDPE core that burned so rapidly. Same material as a plastic milk jug. Unlike the Celotex, it is a thermoplastic instead of a thermo-setting plastic. It melts, that's why it is used to make milk jugs in high volume. You can also find LDPE in many commercial waxes. Unbelievably, the people responsible, basically turned this building into a candle. Ingenuity's Red-Bold earlier post is very informative as to how this fire spread both up & down the facade. Cut up a milk jug and light a piece of it on fire, it burns very easily.