Basement Insulation for Mixed Concrete & Stud Half-Wall
I have not found an explicit answer for how to insulate a basement wall where the bottom is a concrete form and the top is existing 2×6 framing, so wanted to seed the options I have come up with and ask for feedback.
Minimally, I am planning on putting 2″ of XPS across the concrete half-wall portion and then would frame out a 2×4 interior wall in front, with mineral wool filling all the gaps. However in that config I was not 100% for where to put the vapor barrier given the foam is only on the concrete section. I show two possible positions in the graphic included. Logically, position (1) – keeping it on the internal side of the existing framed wall and then taping it to the XPS foam – makes the most sense, but then is there a limit for how much insulation can be internal to the vapor barrier?
The alternative is to just remove the existing vapor barrier on the existing framed portion and then bring XPS all the way up to the ceiling (and frame out the wall to be even with the concrete half-wall or pack that gap with 2″ of more foam). But as I write that out, that seems more complicated and expensive.
Both of those options are shown in the attached images.
Core Question: Is there a preferred path (between these two or something I am missing and a new one option to consider)?
Finally, the floor is slab on grade concrete, and I am leaning towards DriCore Subfloor R+ (https://dricore.com/products/dricore-subfloor-r/) to balance the thickness / height issues I am working with – if there are suggestions here, I am all ears too!
Note that I am climate zone 4C (Marine), i.e. Seattle area. Thank you in advance for your time and input!
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