Mastic to seal Thermopan to wood?
Most of our return air ducts are joist or stud cavity bays covered with a product called Thermopan (foil-faced cardboard). I’m looking for a mastic that will seal the Thermopan to wood. I have one area that is hard to reach but I think I can get at it (with a putty knife on a pole) with a good, sticky, peanut butter-like textured mastic. I called Thermopan and they said any UL-rated mastic will do. However, I can’t seem to find anything locally. I would like a product with little VOC outgassing as it will be in our ductwork.
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