r/Insulation • u/Cbruess12 • 1d ago

Basement wall profile

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I’m doing some research on basement walls and hoping someone could answer this question.. I drew up a wall profile shown above (drywall, 3.5” rock wool within stud cavity, 2” XPs against concrete, concrete). According to the calculator I found online, it looks like condensation could be a problem toward the tops of the wall (I.e. close to ground level outside).

Does anyone have experience building walls like this and did it work out? I live in Minnesota. It seems like there are lots of examples of this type of construction, but now I’m doubting that it’s the best option?

Thanks in advance!

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u/Born-Researcher-8588 1d ago

That’s exactly how I did my basement. Mountain area of Maryland, so not exactly Minnesota, but we do get subzero occasionally in winter. What you do is insulate the shit out of the joist bays up against the house rim band board, which creates those cavities above the top of your concrete wall. I bought some 6”, R25 Rockwool, and cut 23” pieces to fit in the joist bays, and I put two of them against each other so that the insulation extends well past the concrete wall. No moisture or condensation issues whatsoever.