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michael · 12-15-13, 05:25 PM

Just one more thing about reflective insulation: Based on my reading of the Wikipedia article on multi-layered reflective insulation and a look at many reflective products that are for sale, it seems to me that most products would have little use because the reflective layers are pasted or attached to both sides of something relatively solid (such as foam or paper) preventing any reflection at the attachment. I've also noticed from past experience that most reflective products don't hold up well under a house at least in this region. After a few years they become oxidized and dull, and to make matters worse, banana slugs eat off the foil cover and then eat the foam or paper. I did, however, find one product sold by PEXsupply.com (concrete barrier foil) that has a reflective layer sandwiched between two layers of bubble film, so the reflective layer is protected from oxidation, and it is held apart from the warm surface by the bubble film a distance sufficient to allow radiant energy to be emitted and reflected back. It is, unfortunately, rather expensive, but to my thinking, it meets the requirements of effective reflective insulation that has a chance of surviving time, moisture and other damaging elements. It claims an R value close to 4, and I can picture using it between the sub-floor under-side and fiberglass insulation between the floor joists in order to boost the total R-value and reflect back at least a portion of the otherwise wasted radiation from the sub-floor. I'm reluctant to seal off the floor joist bottoms with a film because in this location it has been known to lead to vapor buildup within the joists, condensation and rotting. That outcome might be reduced or eliminated by the presence of a heated floor, I don't know, but I consider it too great a risk. The local building inspectors will no longer allow sealing joist spaces in a way that completely prevents the movement of air because of the fear of the entrapment of moisture. Kraft paper covered fiber glass should allow the joist spaces to "breathe" sufficiently to allow moisture to escape. Just random thoughts...not trying to upset the apple cart.

12-15-13, 05:25 PM	#386
michael Michael Join Date: Feb 2013 Location: mendocino, california Posts: 67 Thanks: 7 Thanked 2 Times in 2 Posts	Just one more thing about reflective insulation: Based on my reading of the Wikipedia article on multi-layered reflective insulation and a look at many reflective products that are for sale, it seems to me that most products would have little use because the reflective layers are pasted or attached to both sides of something relatively solid (such as foam or paper) preventing any reflection at the attachment. I've also noticed from past experience that most reflective products don't hold up well under a house at least in this region. After a few years they become oxidized and dull, and to make matters worse, banana slugs eat off the foil cover and then eat the foam or paper. I did, however, find one product sold by PEXsupply.com (concrete barrier foil) that has a reflective layer sandwiched between two layers of bubble film, so the reflective layer is protected from oxidation, and it is held apart from the warm surface by the bubble film a distance sufficient to allow radiant energy to be emitted and reflected back. It is, unfortunately, rather expensive, but to my thinking, it meets the requirements of effective reflective insulation that has a chance of surviving time, moisture and other damaging elements. It claims an R value close to 4, and I can picture using it between the sub-floor under-side and fiberglass insulation between the floor joists in order to boost the total R-value and reflect back at least a portion of the otherwise wasted radiation from the sub-floor. I'm reluctant to seal off the floor joist bottoms with a film because in this location it has been known to lead to vapor buildup within the joists, condensation and rotting. That outcome might be reduced or eliminated by the presence of a heated floor, I don't know, but I consider it too great a risk. The local building inspectors will no longer allow sealing joist spaces in a way that completely prevents the movement of air because of the fear of the entrapment of moisture. Kraft paper covered fiber glass should allow the joist spaces to "breathe" sufficiently to allow moisture to escape. Just random thoughts...not trying to upset the apple cart. Last edited by michael; 12-15-13 at 05:29 PM..