Attached garage with steps leading into basement
We are building in SE Wisconsin. Currently just figuring out floor plan, in a rough design stage. Main level of house approx 1 ft above grade to approx 4 ft above grade on south side. Basement of house to be partially finished on south 1/2 of house. Attached garage on north side of house. Garage to be on same level as main floor of house. My questions deal with having a stairway in the garage leading to the basement level.
I would like to insulate the exterior of the basement walls. My reasoning is that the basement is going to only be partially finished and I want to keep it dry and warm as possible. I want to stop moisture and cold from getting into the concrete as much as possible from the outside rather than putting up a barrier inside.
So I am concerned on how to deal with the stairs from the garage, an unconditioned space to the basement, a conditioned space.
How is this situation treated as far as footings below the frost line? I assume that the bottom of the stairwell Or at the very least the basement floor has to have footings down an addition depth because the stairwell floor is now effectively “ground level”.
If I put either rigid foam or mineral wool on outside of basement walls do I insulate to the door opening on the bottom of the stairwell then pour concrete for stairwell up to the insulation effectively sandwiching insulation between basement wall and stairwell walls and floor?
Would it help to not insulate outside of stairwell walls below grade and build walls that could be insulated above garage floor adding an additional door on the top of the stairway. This would add a buffer area that would be “heated” from the ground in the stairwell and trapped there by the insulated walls above the garage floor.
Thanks for all responses.
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