Interior foam insulation in Climate Zone 4 (marine)
We are currently renovating our house and wanted to get some help on adding interior insulation. Our house is located in Seattle and is a single story rambler with 2′ eaves.
It has has brick facade, drainage gap, 2×4 framed walls, and no current insulation. The great room that we are currently renovating has a vented cathedral ceiling where the rafters start out with a 5″ depth and increases to 23″ depth as it gets closer to the ridge.
For the exterior walls:
brick facade > drainage gap > 2×4 framed walls > 3.5″ roxul batt > 1″ rigid foam board > 5/8″ drywall
a) fiber glass batts between rafter bays > 1″ continuous rigid foam board > 1×3 strapping perpendicular to joists > 3/4″ rigid foam in between strapping > drywall
b) fiber glass batts between rafter bays > 2×2 strapping perpendicular to joists > 1.5″ rigid foam between strapping > drywall
Would these insulation plans work? If I seal the seams with sicrall tape would the rigid foam provide enough of a vapor retarder or do I need to use an interior wall membrane like majrex?
Thanks for your help. Any advice is greatly appreciated.