I would get the MSDS from the installer and a statement in writing that this material is non-flammable.
If it is foam like I am imagining, it ISN'T non-flammable at all.
Having this sort of thing in such close proximity to a possible bad connection of what-not, is just asking for trouble.
There are better ways to achieve a good seal in boxes, you just need to use a bit of grey-matter.
You also have to ask about the quality of the house construction, if the building cannot be heated to any great degree.
I'd be talking to the Contractor about that, it is HIS problem.
