You are deliberately splitting hairs here. It was so flammable it went up like an oversized fire lighter with a burn rate of 2m/minute.
The only thing that is certain at the moment is that the concrete building was encased in a layer of cladding that as installed in that configuration was well more than an order of magnitude more flammable than its paper specification (if the manufacturers are to be believed).
The other thing that is certain is that the horizontal fire breaks that should prevent the fire from moving from floor to floor were either defective, not present or ineffective (or a combination of those).
The cladding was dodgy by any reasonable definition and it seems from more recent reports was already banned in the USA for taller buildings. There was a more fire safe version of the outer cladding available at slightly higher cost.
I have been looking at the fire testing specs online ISO 1182 and ISO 1716 (I'm too mean to pay for the standards themselves) but I think I now see how you might have a material that passes the ISO lab tests but is absolutely lethal in large flat panels on the side of a building. See:
No disrepect intended to the company making the ISO 1182 tester - it isn't their fault that like with car exhaust emissions tests manufacturers will game the system to pass the specific tests used.
It is a case of what you measure gets controlled. The ISO measurements need to reflect how building cladding will be used in the real world.
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