1 inch or 2 inches of closed cell in cathedral ceiling, then Rockwool?
I’m trying to determine if it is wise to have 1 or 2″ of closed cell foam applied to my cathedral under roof areas, then install Rockwool. House located in Adirondacks, New York State…climate zone 7-8. Considerations:
1. Roof and soffit areas are not currently cut for venting
2. Concerned installation of Rockwool alone and venting soffit areas and cutting roof at ridge for venting will lead me to having to frame air gap space in bays with lumber (Styrofoam proper vents not trusted…fear they may collapse). Proper vents will get crushed if using two batt thick 5 1/2″ Rockwool …tried this once before. Seeking at least R46 performance).
3. Membrain install expensive and laborious…I believe inch or two of closed cell foam will eliminate the need for this vapor barrier which I have used in the past with good results.
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