1)I don't know much about how much FOAMULAR or other rigid foam
insulation boards outgas, or over what period of time. I am confident,
however, that neither concrete blocks nor the mortar between them
provides a very effective air barrier, and that the air barrier properties of
that assembly will deteriorate over time. So, if the goal is to seal the living
space from the foam, you need to install an air barrier. Properly sealed
drywall, for instance, is a good air barrier.
2) Since I don't know what your situation is, I can only guess why you
want/need thermal mass in that location. How much mass do you need?
Since space doesn't seem to be the issue, what about framing a wood
stud wall, filling it with sprayed cellulose or rock wool or dense-pack
cellulose, cover it with air-sealed drywall, & add your mass as an interior
brick or rock or narrow block veneer or, for that matter, additional layers
of drywall. Just a thought.
3) However you do this, it sounds likely that you will make your house
tighter. Is the woodstove decoupled from the living space--i.e., is the
combustion air piped directly into the stove, and is the flue/chimney
sealed from the house? Do you have a digital CO meter installed? You
probably want to consider that if you haven't already.
AEC Applied Building Science Center
909 Capability Dr.
Raleigh, NC 27606
>>> Lawrence F. London, Jr. <firstname.lastname@example.org> 02/10/97
I need to insulate the interior surface of a concrete block wall in my
house with Dow Cornings's FORMULAR rigid high density insulation
(FORMULAR 600, which has the highest density/PSI rating). This is in my
living space in a room heated with a woodstove. I plan to construct a
cavity wall to cover this insulation and to provide thermal mass, i.e. the
insulation will be sandwiched between two block walls and sealed
against contact with room air with cement and caulking as necessary.
Does anyone know whether FORMULAR will outgas toxic fumes over
the short or long term? Will my containment system be adequate to
prevent infiltration of any possible toxics into my living space? As it will
be exposed to moderate heat due to proximity to the outer block wall
warmed by the woodstove I am wondering if this factor would result in
the stimulation or acceleration of outgassing.
If FORMULAR turns out to not be acceptable for this application does
anyone know of a rigid insulation that would be?
Many thanks for any advice or pointers to resources on this subject.
Some of you may find my renewable energy page interesting.
Chapel Hill, N.C.
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