Complicated Roof and 100% Cathedral Ceilings from 1978 – How to Insulate?
My house is built in 1978 and has cathedral ceilings throughout the house – there are no crawlspaces or attics. The rafters are 2x8s and I live in Zone 6 on Lake Michigan. The roof is unvented, there are no soffits and no venting channels. From the inside out it is drywall (or tongue and groove in some rooms, plastic vapor barrier, fiberglass batt insulation, decking, asphalt shingles.
I want to replace roof and improve the insulation situation as the rooms with tongue and groove on the ceiling have noticeable condensation issues, which tells me that there is condensation above the drywall in the other rooms too, but it hasn’t manifested itself to the inside yet.
I intend to have the shingles and decking removed regardless, so this would be a good time to blow in closed-cell insulation from the outside in if that’s the best option. I want to fix the condensation problems.
One roofer I received a quote from suggested using the intake vents for both the intake and the exhaust on each roof plane and putting rafter baffles in each each rafter. The image in this post shows where all of these vents would have to go.
Another option seems to be blow closed-cell insulation from the outside in. Then potentially put rigid foam on top of the decking and leave the roof unvented? Please let me know the best way to approach.
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