Vented or Unvented Roof with Exterior Rigid Foam
The question of venting or not has been discussed many times on this site. Unfortunately we still do not have a definitive solution that satisfies both our architect and our roofer. I am wondering if the experts would chime in. We are renovating a wood frame 640 sf cabin in zone 5 with a cathedral ceiling. One of our roof slopes is 2.5/12 the other slope is 7/12.
- Given that we have the minimum board insulation on the exterior, is venting below the cladding adding any extra value?
- Does the vapor permeability difference between polyiso and GPS relevant here?
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