What is a safe insulation near a heat source?
It appears that many (if not all) of the commercial spray foam insulants include warnings that they not be used near heat sources like radiators. What, then, can be used to close up a 1/2″ gap between the steam radiator pipes and sheet rock?
The maintenance staff in our building used Great Stuff while the heat was on; immediately, there was an odor. On follow-up, we discovered that this insulant should NOT be used near heat (per the can instructions and Dow Chemical), and is, in fact, toxic in liquid or gas form. Now, the building mgmt. has brought in “specialists” to remove the Great Stuff foam (which melted upon application). But each spray foam suggested has similar warnings.
Are all of these foams safe to if the radiator is stone cold? Will the chemical properties of the insulant stay inert when the radiator is turned on? Are some foams safer near heat sources? Or is there some other kind of insulation that would be safe/non-toxic?
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Replies
Beth, a mineral wool such as Roxul is safe near heat. It is air- and vapor-permeable however.
Thanks Michael. One more question. Can Roxul be used in an HVAC system? Would it be appropriate as moisture and air barrier? (That's why I've been told the area around the pipe needs to be sealed.)
Beth,
You can buy pipe insulation that consists of mineral wool and a vinyl jacket. The vinyl jacket is the air barrier and vapor barrier. If you want, you can make your own pipe insulation -- first Roxul, then polyethylene -- but it's easier to buy the pipe insulation at Home Depot.
Seems that there are2 distinct issues here. First is the air seal of the opening through the drywall, next is the insulation of the steam pipe.
I would use coil stock to fab a square with a hole in the middle the size of the pipe, actually made of two pieces that overlap in the middle. slide this in place and secure the coil stock to the drywall. Seal the small gaps at the pipe/coil stock with high temp caulk. This will provide the air stop. Then insulate the pipe as recommended above.