Rooftop rigid insulation and solar panels
We are in the design phase of a modest story and a half house in SE Minnesota, zone 6. My builder suggested room in attic trusses for our upper floor, as well as a few inches of closed cell foam on the interior against the roof deck, followed by fiberglass or cellulose. I realized that may not be enough to control moisture in a cold climate and am debating getting a quote on 4 inches vs looking into rigid foam on the outside of the roof deck. One detail that makes it interesting is we are looking at a bonus room above the garage as well. We plan on using metal roofing of some sort.
My questions are: Can someone help me cost compare the two options for my area as well as help me understand the right way to install the exterior foam so that I can install solar panels in the near future? (Sheathing vs strapping) A polyiso/esp combo seems appropriate to me, but expensive. (I would love to find reclaimed) Also, can someone direct me to some pictures of what a thick roof like that will look like when done?
Thanks for the help.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part