Woods Hole house spray foam fire

Polyurethane spray foam insulation installed incorrectly along eaves caused a house fire. Used to illustrate that polymer foams are the lowest-thermal-conductivity material in the world — but the same property makes them dangerous if installed where heat can build up internally. Tom shows a charred sample.

I know a guy at Woods Hole — he was rebuilding his house and his house burned down last year because of the way it was installed. This is the fire — you can see it's charred. They were squirting it along the eaves, and they didn't pay enough attention. You can see the surface is a little darker on this side, and you can see the internal layer heating up. With a thermocouple down in here, 100 degrees. You can put something very hot here and you won't feel it through — it's a good insulator. Faster — there's data on this — more oxygen on the surface, the polymer actually forms carbon, and it starts to overheat. If the heat reaches the oxygen, it'll burn down your house. So it's safe when installed with instructions, except when the omission gives the right instructions, sorry.