Combination of Insulation Types
To insulate our home near the coast in Long Beach, NY we are looking at a combination of rigid foam board for the exterior and spray foam for the interior. We wish to achieve an R-value of about 20.
Since we should not use a vapor barrier on both the outside and inside, which option would you recommend:
Option 1) 2″ close cell spray foam insulation (vapor barrier) for an R value of 14 on the inside with a 2″ expanded polystyrene foam board (non-vapor barrier) for an R value of 7 on the outside
Option 2) 4″ open cell spray foam insulation (non-vapor barrier) with an R value of 14 on the inside and a 1″ polyiso rigid board on the outside (vapor barrier) with an R value of 7
Option 3) some other option
Also, we are using 3″ close cell spray foam for the crawl space. Any suggestions for achieving an R value of 49 in the attic?
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