Aaron Fude wrote in news:6a750d88-3317-4e8d-bba0-
:

I've heard about all the advantages, but:

1. Could it be so heavy that it jeopardizes the stability of the roof
in a roofline application?

The heaviest foams are about 2 lb per sq ft while roofs are supposed to be
designed for loads from 25 to over 50 lbs per sq ft. So the foam won't
overload your roof.

2. The gas that it traps inside - I'm sure it slowly leaks over time -
what type of gas is it and is it dangerous?

There are many different chemicals used for the foams but a good guess
would be that the foams could off-gas. These foams are used in many houses
so if you use one of the better known brands you would be safe. If this is
intended to be a living space you could get additional gas proofing by
using a vapor barrier over the foam. If it ia an open attis area then the
normal ventilation should prevent gas build up.


Thanks in advance,

Aaron