Must fiberglass insulation always be used to insulate Underfloor Matts, instead of say, rigid foam boards, cut to fill the bay and sealed with a bead of foam or caulk? Also, can a reflective,(foil) barrier be installed beneath the Matts, to help direct the radiant heat, up toward the underfloor?
Post by Watts Radiant on May 5, 2010 14:17:55 GMT -6
You can use the rigid insulation as you described. We usually suggest fiberglass as it's the most common material used in this application, as well as the cheapest. Be sure to leave an air gap between the insulation and the mats, i.e. do not push the insulation boards up against the mats. You can also foil as you described which will provide some reflective gain to the system.