How do you insulate a cathedral ceiling?

Raoul Lions
Updated: Aug. 7, 2020

to vent or not to vent a cathedral ceiling. 

I'm leaning towards not venting my cathedral ceiling and using closed-cell spray foam insulation.  My walls are double 2x4 stud walls 12 inches deep and will have 2-3 inches of closed cell spray foam insulation to create a air and vapour barrier first, then the rest of the cavity will be  filled with dense pack cellulose insulation, with an intello vapour barrier holding cellulose all in. 

I'm wondering if I can do the same for vaulted ceiling? or am I better off going with straight closed-cell foam insulation. 

The builder is using 16.5 deep trusses 24” off centre, I want to achieve R-80 in roof. 



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