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Sealing rafter roof for SIP home const – GreenBuildingAdvisor
user-1072251 | | #1
Whatever else you do, vent the SIPS with 1×3 strapping above the strapping! If you don’t, there is a good chance of shingles falling off in a few years because the SIPS sheathing has rotted off. I’ve seen this more than once and repaired those roofs. Not sure I understand where you are going to spray foam the rim joist, but it doesn’t matter much as the foam will crack in a few years as the wood dries out; it is a short term solution. A quality flexible caulking would last much. longer. I don’t where you are building, but in most areas you need a good vent channel in the rafters – above the insulation. Using the fiberglass or whatever against the roof sheathing can lead to moisture on the sheathing – and rot. (Bob Irving)