What do you pros think of this:
Instead of taking the bottom (i.e. the inside, interior) metal ceiling sheet off to put ceiling insulation on, how about drilling small holes and stick the small do-it-yourself expanding foam insulation dispenser inbetween the two metal sheets and let it fill up inbetween the two meal sheets. Later use epoxy putty to cover the holes and perhaps paint over it all.
Great Stuff (the foam insulator) seems to advise against it because it needs moisture to set.
Can I insulate my walls with GREAT STUFF™?
GREAT STUFF™ sealants use moisture in the air to cure. They are designed to fill small cracks and gaps. The foam does not cure properly if it is used to fill large voids unless it is put down in layers and allowed to cure before the next layer is applied. Do not use GREAT STUFF™ to fill enclosed voids such as behind drywall or under tub surrounds.
Would it provide decent insulation and the expanding foam get too caught up in the old, worn out stock insulation?