Roof structure, insulation and lighting
I am planning a new home in northern Idaho climate zone 6 and have some questions regarding the roofing structure/insulation and lighting within this system. this will be a mostly cathedral ceiling with a flat part across the middle in which I intend to put the lighting and ceiling fans. The thought is to keep these items out of the insulated roof. It will be a non vented roof. I have attached two drawings to help illustrate my thoughts. I would like to build the roof as follows from top to bottom:
1. Dutch Seam metal roofing
2. 2×4 furring strips
3. Two layers of XPS foam total R30 with the seams of the top layer taped (I can to more layers and also consider a sandwich of XPS and Polyiso). Peal and Stick applied over the foam under the furring strips.
4. 1/2″ Zip roofing panels with all seams taped
5. R30 blown in insulation (I am open to any type of insulation in this area)
6. 5/8″ drywall with latex paint and primer
1.Will this system work and be a long lasting assembly (with the understanding that air sealing will be a top priority)?
2. Do I need to install another layer of plywood over the furring strips (my air gap)?
3. Is there a less costly approach to this roof assembly?
4. Will placing the electrical in the flat area of the ceiling solve the issue of air leakage and heat causing problems within the roof assembly?
5. With the Zip panels, can the peel and stick go directly on the foam as the primary water barrier?
Any thoughts would be appreciated and questions are welcomed
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