Dense Packed Cellulose in Unvented Vaulted Ceiling?
I am designing a home for Climate Zone 4A and am planning on having an eave-less roof and vaulted ceiling. Currently, I’m planning on roof rafters being 9-1/2″ I-joists so I can get an adequate amount of dense packed cellulose in the roof cavity of a vaulted ceiling condition (R-30 min.). I’d like to use a smart vapor barrier like the Intello Plus to hold the cellulose in before drywall is installed. I plan for the roof to be sheathed with 5/8″ Zip sheathing and asphalt shingles to be the finish layer.
My big question is whether it would be important for there to be any ventilation space under the roof sheathing. I’ve seen instances where a similar roof construction was just sprayed on the underside for an air tight assembly but I’d like to avoid spraying if possible. Do you see any issues with not venting and packing the roof cavity completely with cellulose?
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