Insulation, Radiant and Vapor Barriers - Using Rigid Insulation as Sheathing

I'm enclosing my screened porch and plan on using vinyl siding on the exterior. I'm concerned about keeping the room warm in winter and cool in summer. As such, I'd like to maximize my insulation where I can. I've heard of using rigid insulation as sheathing under vinyl siding to add additional R-value to walls. Is this appropriate to do? Any drawbacks as far as framing around window openings?

Sure check the window trim and see if it will fit Are block out under them with wood and let the insulation board come up to them. If thats all you have first on the studs Id put the flat metal sway brace on all the corners. Under the insulation board.

ED ;)

I'm enclosing my screened porch and plan on using vinyl siding on the exterior. I'm concerned about keeping the room warm in winter and cool in summer. As such, I'd like to maximize my insulation where I can. I've heard of using rigid insulation as sheathing under vinyl siding to add additional R-value to walls. Is this appropriate to do? Any drawbacks as far as framing around window openings?
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You can use rigid foam insulation either OVER plywood or OSB exterior wall sheathing OR you can use rigid foam insulation IN LIEU OF plywood or OSB wall sheathing PROVIDING you install 'let-in' or other types of structural bracings to stabilize the wall framing.


Either way, installing rigid foam insulation may be the ONLY way to meet and obtain Federally or State mandated energy codes.