Basement Wall Insulation Question
I’m looking for some advice on how to properly insulate my basement walls in Passaic County, NJ. Right on the border of zone #4 and #5. Basement will eventually be finished and conditioned w/ a mini split HVAC unit.
The house is 12 years old, basement is CMU block, painted with 2 coats of Drylok. French drains around w/ floating slab & sump pump. Walls are dry w/ the exception of one very small leak that is due to a gutter which I will fix in the spring.
I’m getting a lot of conflicting information online and from my architect on how to properly insulate. Currently the basement is framed w/ 2×4″s w/ a 1″ gap between the CMU and backside of the stud wall. Architect detail shows to install R13 Rockwool between the studs then green sheetrock but leaving a 1″ gap between the back of the Rockwool and CMU.
However, I see multiple instances of online resources saying that XPS foamboard should be installed against foundation, then 2×4’s and cavities filled w/ batts. Obviously that would pose a problem for me at this point and I would have to rip out the framing to redo it.
I spoke w/ the Rockwool technical department and they recommended that if I cannot remove the studs to install the rigid XPS against the foundation, next best course of action would be to press the Rockwool directly against the CMU; then install a smart membrane like Certainteed Membrain on the inside of the wall prior to installing the sheetrock.
Ideally I’d like to be able to get this done without removing the framing but advice would be appreciated.
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