Oh lord, really?
I've not seen the detailing but if its as described it sounds like a proper dog's dinner.
A couple of things though. What was the insulation actually fixed back to? There must have been some sort of substrate, surely? Also the firebreaks (I can't believe I'm even talking about firebreaks on a building this high) wouldn't need to be in contact against the back the cladding. The whole principle of ventilated rainscreen is that there is a continual vented cavity, a firebreak would block this. Instead you'd have intumescents (expanding chemicals) in there to expand and block the cavity at the first sign of fire.
I queried the presence /performance of the inutumescents towards the start of this thread.
Also fucking mastic. If anyone is still using mastic (which has a design life of about 6 minutes) on facades in this era they need shooting.
Ah, I didn't know about the intumescent strips, but in this situation I can't see how they'd work / can see why they clearly didn't. They're surrounded by insulation so will be insulated from the initial fire for long enough for the flames to have jumped through the air gap. The air gap would create a vertical chimney effect so the flames would shoot up the outside of the insulation in the air gap pretty quickly.
The mastic I referred to would be on the inside of the internal window surround, sealing the corners.
The insulation was fixed to the existing wall, but the window was moved out from the previous position so that the window itself was located around half way into the insulation section, presumably fixed to the sub structure of the cladding in some way. Which means that their would only have been the internal window surround between the inside of the flats and the insulation material (unless there was a fireproof layer at that point, but that doesn't seem to have been the case from the way the fire spread, and I can well see that just not happening.
The external fire breaks can be seen still in place on the pictures of the burned building, about half way between each window section running horizontally.
Scary shit, but frankly I've been expecting to see something like this for a long time having seen how some of these systems work, and also worked in buildings where it's clear that many trades don't give a toss about maintaining fire seals when running their cables etc. I remember one job where we were diligently putting the insulation back into the fire breaks around our cables only to look up and see an entire 1.2m wide roof to ceiling strip of fire sealing material missing completely - reported it but I bet it's still missing. I also see they've now exempted soil stacks from being in fire proof enclosures, because a 5 inch plastic soil stack / vent is completely fire proof by itself and in no way would simply burn and create a 5 inch diameter hole in any fire break.
There's a thread I think on here from 4-5 years back showing a tower block somewhere in Europe where the cladding caught fire in a similar way to this. Criminal that this work was still being done in this way even after that.