Reflective Insulation in Unvented Roof
I’m remodeling with an unvented Cathedral ceiling in Climate Zone 4. I have asphalt shingles, underlayment the rafter cavities that are 9″ deep which were filled with faced High density R-30. Adding exit vents is not a feasible approach and I don’t want to use spray foam for a couple reasons. A contractor today came by and recommended Reflective Insulation (Sold under the Low-E brand) and all kind of reasons why. Reduces transfer, keeps hot from meeting cold thus eliminates condensation, excellent moisture barrier, cheap, easy to install, etc. He gave me a sample, reflective on both sides, small 1/8″ of core insulation. He told me it’s installed under the roof deck (from inside of house) then simply install sheetrock and no need to add any unfaced fiberglass. It has an R-11 value so I think I would add a layer of unfaced R-19 to reach the code requirement of R-30. Will these reflective barriers really keep the moisture away in an unvented space. Any comments or inputs are welcome.
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