Detailing a Vented Cathedral Ceiling
We are in the design stage for a home, we plan to break ground summer 2020.
It’s a very simple 28’x36’ house with a 6/12 pitch vented roof. No valleys. The front 22ft are going to be cathedral ceilings with parallel chord trusses. The rear of the house will be conventional trusses.
Northwest Montana Climate Zone 6
The cathedral roof plan currently is:
Standing seam metal
Rain Gap Furring Strips
Ice & Water Membrane
Sheathing (Taped Seams)
Parallel chord Trusses w/ energy heel (not engineered yet, but estimate 20-24” depth due to span)
– Vented Channel (2” site build rigid foam) foam sealed
– 20+” of dense pack cellulose
Drywall air sealed
Will the dense pack settle and leave uninsulated cavities at the ridge?
When the foam sealed vent channels meet at the ridge how do you seal them to each other?
Do I need some sort of air barrier material under the drywall to protect the cellulose from moisture?
I want to avoid exterior rigid foam but want to minimize thermal bridging.
My thought was if I dense pack the cavity and between the truss webbing I would minimize thermal bridging. Thoughts?
What’s the best way to transition the air barrier and insulation on the vertical wall between the conventional trusses to the cathedral ceiling?
Thanks for any help and advice.
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