Hello –

I have a 1905 house in Seattle, WA. I want to insulate the walls in the above ground basement walls from the interior. The house has 4 layers starting on the inside = 1) empty stud bays, 2) wood cladding (vertical), 3) asphalt siding (may have fiberboard below it) and 4) vinyl siding.  There is ample air flow through the walls today (evidenced by some fiberglass batts, black but dry, stuffed sporadically). Humidity is HIGH (75-80).

QUESTIONS:
1. Given the asphalt siding on the exterior, is it safe to insulate the wall, provided I let it dry to the interior?
2. If yes, is this plan acceptable?  – Comfort Batt (R23-R30) directly in stud bays, then drywall. NO interior vapor barrier.
3. Would dense packed cellulose be better than mineral wool b/c it moderates moisture better?
4. Would a smart vapor barrier, like MemBrain, need to be added? Since I’m drying to interior is that best on the empty bays BEFORE the insulation?
5. Should I also air seal the empty bays before adding insulation? I suspect no since it needs to dry to interior, but checking in case 😊

Thank you!!

PS – w/o the asphalt siding on the exterior I would have done an airgap (rainscreen) + 2″ rigid foam + mineral wool. I think that’s out tho as the asphalt prevents exterior drying.