Cathedral celling insulation technique in a northern climate
I have seen a few discussions about insulating cathedral ceilings but none that relate to the method that I had in mind for my 24′ cathedral here in Vermont.
* Penetrating water sealer on all surfaces that have the potential to rot.
* One inch strapping to create an air gap for ventilation.
* Multiple overlapping layers of ridged foam(open or closed cell?)
* All seams taped because expansion and contraction will break a DIY spray foam seal.
* One or two inches of spray foam insulation applied professionally to hopefully create a secure air seal. Total ridged foam is enough to prevent condensation from temperature variations of the outside and indoor air. What happens when the air seal fails despite your best efforts?
* R 30 batt insulation
* Vapor barrier, vapor resistant or nothing?
* A layer of ridged foam over the celling joists or would it be diminishing returns?
* If a wood celling, Sheetrock first?
* No recessed lighting.
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