Cold climate basement insulation and code questions
I live in SE Wisconsin (Climate Zone 6) in a 1930s house that has a currently unfinished cinder block basement with a concrete slab floor. The basement is unconditioned but stays at or above 55 degrees in the dead of winter. Basement walls are 95% below grade, and there are some small windows at the top of the walls. The house is heated with hot water radiant heat but there are no radiators or other heat / HVAC sources in basement.
I would like to add a rec room in part of the basement with finished walls and a floor and ceiling, as well as a workshop. I do not plan on adding heating or cooling, other than using an electric fireplace on occasion as a heat source in the living room.
I’m planning on using 2″ XPS (R10) foam board on the perimeter walls and butting 2×4 wall studs up to the insulation. I’ll either drywall over that or use some other type of finish wall paneling. I have read that Code requirements for basement wall insulation in climate zone 6 are R13, but does that apply to this situation? Is this even a finished basement if there is not a heat source and it is not otherwise conditioned? I am not sure I meet other Code requirements for finished basements either, as the max. ceiling height is about 6’6″ or slightly less after I add a floor and ceiling. Is there a risk of condensation issues if I am only using 2″ of R10?
Other question is whether I should insulate the entire perimeter of the basement or just the perimeter walls adjacent to the rec room area. Due to some gas and waste pipes running parallel to a wall about 1.5″ inches from the wall (that is not adjacent to the rec area), I cannot get 2″ of insulation and framed walls there. Any recommendations for how to handle that without rerouting pipes? Can I use foam faced polyiso and leave it exposed? Or does use of that risk condensation issues?
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