Hot Roof – Cathedral Ceiling
I am in the process of insulating my cathedral ceiling. I have searched through the site but haven’t found exactly what I’m wondering.
Originally I planned on doing full depth closed cell spray foam (as shown here: https://www.greenbuildingadvisor.com/blogs/dept/musings/how-build-insulated-cathedral-ceiling#ixzz5GzUfq9Pr)
The problem with this is that the spray foam contractors I have talked to have been reluctant to spray this deep since they think it is not only unnecessary but that it will also be difficult and time consuming since they have to spray 1.5″-2″ at a time and no more than 3″ in a day (or so I’m told).
So I’ve been weighing my options as far as closed cell depth vs. a mix of closed cell and fiberglass/mineral wool (as described in the article linked above) but my main question is about interior rigid foam.
I am wondering about doing adding an interior layer of rigid foam to boost r value and reduce thermal bridging (I’m nervous about Ice dams). I would like to use XPS foam but I am concerned that this will prevent drying to the inside.
I have attached one of the design ideas I have, like I said, the foam vs. batt insulation ratios are up for discussion but my main question is about the interior rigid foam with a hot roof design.
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