Architect Lloyd Alter on Treehugger.com presents a short analysis of the disastrous Grenfell apartment high rise disaster in London in reaction to a Daily Mail article proclaiming it to be the result of a preoccupation with green building materials. His conclusion:
In this case, the fire came from the outside. Note how on the original drawing [omitted – HW] submitted to planning, the cladding is zinc. Somewhere along the line it was changed to Reynobond PE, a sandwich of thin aluminum with polyethylene in between. This is similar to Alucobond, and both are very common cladding materials. I have used them myself in the last building I designed as an architect. It acts as a rain screen; there is then a two inch cavity and attached to the building, six inches of Celotex RS5000 polyisocyanurate rigid insulation.
The problem is that the originally specified zinc is totally non-combustible, whereas the Reynobond is not. We do not know why the change was made, but it is obviously, in retrospect, significant. According to The Construction Index, alternatives were available. “Reynobond PE is not as fire retardant as the alternative Reynobond FR, which has a mineral core, but it is lighter and so easier to install.”
What appears to have happened is that the Reynobond’s polyethylene core caught fire and the stack effect in the two inch gap made it spread almost instantly. Apparently it got hot enough that the supposedly flame-retardant polyiso charred as well, putting out tons of smoke, possibly contributing cyanide and other toxic gases. The vinyl framed windows also melted, letting the toxic fumes into the suites very quickly.
And this was interesting, too:
Literally for decades I have complained about the North American way of designing apartment buildings, with two big pressurized stairs and a corridor in between, all designed to be big enough to evacuate the building in minutes. The Europeans had so much more design flexibility with their single stairs and units opening up onto landings.
But in retrospect the North American approach of Get out fast and get out now appears to be a whole lot better than the European one of Stay put and we will rescue you. As an architect, reading the story about the young Italian couple calling home while they wait to die was like a stab through the heart. I will never complain about the two exit requirement again.
He also notes that there are already some folks who want to use this tragedy to condemn wood buildings. Modern wood construction using cross-laminated timber doesn’t burn like this, but instead chars and takes literally hours to catch fire – not moments, as happened in London. I gotta hope that a careful, sober analysis takes place and takes precedence, rather than permitting commercial interests to use this to trash an up & coming competitor, using the political world’s “post-factual, post-policy” faux-approach to conducting business.
