Unvented Cathederal Ceiling for Lake Tahoe – 6200 Feet – Ice Dam Galore
This building’s covering consists of 5/8″ drywall, fiberglass, rafters, 3/4″ plywood, tar paper, and cedar shakes. The insurance company is insisting on a new non-wood roof due to local fire hazards. It’s at 6200 feet in the Sierra Nevada mountains.
The owner does not want the roof to look chunkier. I am concerned with the ice dam potential, thermal bridging of the rafters, and of course air leaks into the cathedral ceiling section.
The job starts late April.
My first thought was remove the 3/4 ply, air seal from the top, discard the fiberglass, install rockwool, add 2″ or 4″ of Hunter SIP panels, then an impermeable membrane and the fire resistant shakes.
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