Hello,

I’m working on a home design and wanted to ask for any constructive comments the community might have. We are looking to build a very well-insulated envelope with a straightforward process that most building crews could implement. Cost is not the primary factor, insulation-value and durability is. This is in climate zone 5.

I’ve attached my first pass at a shingle roof (RF-1) and stucco wall (PL-1). The basic concept I am working with is that the exterior Zip sheathing on walls/roof is our water/air barrier that will dry to the exterior. The interior side of sheathing and framing would be coated in a generous pass of closed-cell spray foam, creating an impermeable air layer. This prevents the condensation issue of interior vapor reaching the exterior sheathing. Extra space in the cavity would be filled with readily available batt insulation.

Walls get Zip R12-Sheathing for the thermal break. The roof gets a layer of rigid foam on the interior side for a thermal break. I looked at options for applying foam to the roof exterior (nailbase, for ex.) but I thought it would be simple and hard to mess up the continuous seal between the Zip R wall sheathing and Zip roof sheathing if I kept it exposed. Would it be problematic to layer additional rigid insulation on the exterior roof sheathing as it would inhibit drying?

I’ve attached some detail drawings showing what I currently have.

Thank you!!!