TBren46501@aol.com Tue, 11 Feb 1997 08:14:36 -0500 (EST) Hi Lawrence. Under ordinary conditions extruded styrene mainly outgases the blowing agent. Most of this is gone within a few months of manufacture (the exponential decay of R-value is probably a good indicator of time constant of decay). They used to blow it with a CFC but I believe they changed that some years back. I've used it in buildings with people who are very sensitive to chemical exposures with no difficulty. John Bower has had the same experience. If the material is heated up, it is likely that at some point the long molecules will pyrolize, producing compounds that are the products of thermal degradation and are not found in the list of materials used to manufacture it. Almost certainly some of these will be irritants. The thermoplastics generally begin changing in the greater than 140xF range. It's unlikely that you would encounter these temperatures inside a CMU wall. I've used the foam in exactly that application, no problems for 15 years. ---+*+--- JBunzick (JBunzick@dprarchitects.com) Tue, 11 Feb 1997 09:14:18 -0500 I don't know whether foamed polystyrene outgasses, though I have not heard of this problem. I disagree with the reply comment about it loosing its blowing agent in 6 months. This foam is closed-cell, and it looses its blowing agent much more slowly than the polyisocyanurates, which have permeable cell-wall membranes. They do loose their blowing agent in 6 - 12 months. This process occurs progressively more slowly as air replaces the blowing agent, thereby lowering its insulation value. Polystyrenes are not known to loose as much R-value, though they don't claim as high an R-value to start with. The end result is that both types, polystyrene and polyisocyanurate, end up with similar R-values over time. The polystyrene is also less water absorbent. To clarify brand names, Dow Chemical Company (not Dow Corning) makes Styrofoam; UC Industries makes Foamular (with an 'a', not Formular with an 'r') though I believe they have been sold but can't remember to whom; and Amoco makes a foamed styrene called Amofoam. I am wondering though, why you plan to use the higher density material. The higher density material will cost you more, but it has the same R-value per inch. The higher density is intended for use in deck insulation situations where there are compressive loads on it. John Bunzick, CCS, CCCA Dean Architectural Alliance (new name) jbunzick@dprarchitects.com ---+*+--- Bruce Sullivan (sullivan@crest.org) I would be concerned about air quality issues raised by the wood stove in addition to the foamboard. Considering combustion air and adeqate removal of the products of combustion would be part of the process. I would also consider the potential for moisture condensation in the cavity behind the insulation. Addressing basic building construction concerns such as these is often serendipitous. Greg Flynn Raleigh, NC bnartist@aol.com http://members.aol.com/bnartist ---+*+--- Arnie Katz (AKATZ@AEC.NCSU.EDU) Wed, 12 Feb 1997 15:03:33 -0500 Lawrence: A few comments that may be of help: 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. Arnie Katz AEC Applied Building Science Center 909 Capability Dr. Raleigh, NC 27606 919/857-9029 akatz@aec.ncsu.edu ---+*+--- Bruce Sullivan (sullivan@crest.org) Wed, 12 Feb 97 12:59:04 -0700 Posted by Bruce S., due to some technical problem: --------------------------------------------------- From: loren@cstone.net (Loren Abraham) It is almost a certainty that ALL foamed insulation products outgas a variety of organic compounds. In my opinion the compounds which are outgassed by styrene products ar less offensive (and less harmful) than polyisocyanurates. mid (methyl isocyanurate) which is the catalyst is a close relative relative of mic (methyl isocyanate) of Bhopal fame and although less unstable is still very toxic and easily absorbed through th skin. It is not safe to handle poly isocyanurates until totally *cross-linked*. Other things can be outgassed as well. I would really like to hear Hal Levin comment on the relative safety of polystyrene and poly isocyanurate foam board. In any case PLEASE do not mess with foamed in place poly-iso insulation products. These chemicals should never be taken out of a carefully controlled manufacturing environment and in my opinion are not safe in any environment. The idea of adding normal casein glue to blown in cellulose sounds rather nifty to me. Hal? -----========+++*+++========-----