Roof insulation on new build — newbie question
We are building a 1200 square foot house, cape cod style, 1.5 story (so upstairs has one bedroom, storage, and some general living space). The house is located in climate zone 5 and close to climate zone 6 in the Pocono mountains area of PA. We are building the home ourselves – not as green as we would ideally like because of our limited budget and desire to have as little debt as possible, trying to stay on the green side where we can manage it.
The question – we used 2 x 10 rafters when building the roof and later realized that we cannot quite achieve the code-required R-38 with batt insulation (oops). We were wondering whether it would work to put R-30 batts in and then add rigid foam insulation sufficient to bring our roof R value up to 38 or slightly better. We would then attach the drywall to the rafters through the rigid foam.
If this is a good idea what type of rigid foam is our best option (considering that it is an interior-ish application) and do we then use faced insulation batts or unfaced?
Or should we just suck it up and rip down 2x4s to the right dimension and attach them to each rafter so we have space for the R-38 batts?
Any other suggestions would be appreciated – these are just the ideas we came up with.
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