Insulating and Sealing Concrete Block Cavities at Sill Plate
Long time reader, first time poster. I am using 2 inch XPS and spray foam to insulate my rim joists with R15 unfaced mineral wool on the warm side. My sill plate is sitting on concrete block with about 2-4 inches of the block cavity exposed. I’ve read solutions on filling those cavities with loose batt insulation and sealing off with spray foam. I am wondering is it possible to just use blueskin or similar peel and stick to cover the cavity holes. Is it necessary to stuff loose insulation? Alternatively, could I lay a sill plate gasket to cover the cavities and secure using a 1×2. I’m not opposed to spray foaming each cavity but rolling out the peel and stick or sill gasket would be much quicker. I am in upstate NY/zone 6. Any thoughts or suggestions would be great. Thanks!
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