T&G cathedral ceiling with 1/2 inch XPS instead of gypsum wallboard?
Hi out there,
New to this forum, thanks for having me.
Jumping right in. I’m getting ready to insulate and finish a cathedral ceiling in a small cabin (~600 sq ft of lid) and trying to get the details right.
I’ve been reading the suggested courses of action elsewhere on this site (https://www.greenbuildingadvisor.com/blogs/dept/musings/how-build-insulated-cathedral-ceiling) and here is the plan I’m thinking of at the moment:
The rafters are 2×10 @ 24″ oc. There is 1″ of screened vent above the bird blocks and a vented (metal) ridge, and I plan to insulate with r-30 fiberglass, leaving 1″ vent space at the top of the rafter bays.
The ceiling finish will be t & g doug-fir. The linked article strongly recommends taped drywall underneath the t&g to act as an air seal – but my thinking is that 1/2″ xps (closed-cell foam) with caulked seams would accomplish the same thing as taped gwb while also adding additional R value.
Does anyone have an objection?
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