I inspected a home built in the early 70s today and the crawlspace had 1/2" thick 4x8’ Styrofoam insulation installed to the bottom of the floor joists. Am I right to assume this is not a correct application because moisture/condensation can be trapped between the floor joists? Also I’ve heard of fire hazards with Styrofoam insulation. There was no crawlspace access. By removing some of the wall vent covers I was able to observe the crawlspace.
Thank you for your help,
Steve D.
Styrofoam burns well and gives of a hazardous gas . It must be covered .
Doesn’t matter if it’s covered or not. Insulation has to meet a specified flame spread index, even in concealed spaces.
"IRC R302.10.1 Insulation. Insulation materials, including facings,
such as vapor retarders and vapor-permeable membranes
installed within floor-ceiling assemblies, roof-ceiling assemblies,
wall assemblies, crawl spaces and attics shall have a flame
spread index not to exceed 25 with an accompanying
smoke-developed index not to exceed 450 when tested in accordance
with ASTM E 84 or UL 723.
Exceptions:
-
When such materials are installed in concealed
spaces, the flame spread index and smoke-developed
index limitations do not apply to the facings, provided
that the facing is installed in substantial contact with
the unexposed surface of the ceiling, floor or wall finish. -
Cellulose loose-fill insulation, which is not spray
applied, complying with the requirements of Section
R302.10.3, shall only be required to meet the
smoke-developed index of not more than 450."
Confuse if there is no access how did they get 4x8 sheets in there ? Been there since the 70’s?
Just be sure it is what you think it is