Use less insulation in South-facing wall?
I’ve been discussing the frame wall assembly of our South-facing wall with my architect. The home uses some passive solar design, so the South wall is tall (just under 21′) with a lot of windows (19). I am using 2″-3″ of exterior rigid foam on the other walls, but he suggests going with less foam and using OSB sheathing on the South wall. His reasons are 1) there is very little insulated wall on the South elevation, so the rigid foam may not make as much of an impact, and 2) this would enable us to use standard 6-9/16″ extended window jambs. Does it make sense to reduce insulation to allow for more standard-sized window jambs? I’m concerned about my sheathing falling below the dew point temp.
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