Kraft-faced Insulation at Shed Roof
The shed roof shown in the attached photo is built with 11 7/8″ high I-joist rafters. After reading this article once again (https://www.greenbuildingadvisor.com/article/how-to-build-an-insulated-cathedral-ceiling), I’m embarrassed to say that I still have a question. For the ceiling insulation, we are planning on using R-38C, which will give us about 1 5/8″ air space above the batts. We have created vent holes in the webs of the I-joist blocking, and rigid foam baffles at the top and bottom of each rafter bay. Please see Eave and Ridge Details, attached. The R-38C is below the code minimum, but we have approval from the building inspector. We have insulated the walls with Kraft-faced R-21. The project is in the Columbia Gorge, in Climate Zone 5B.
Please also see my other question, here:
Question 1) We DO want to use the Kraft-faced R-38C, right? To provide a vapor-retarder layer. The ceiling will have drywall, with latex primer and paint.
Side note: thanks to supply-chain problems, we’re not sure when the R-38C will be available again.