In our basement we have two different framing setups that support our joists. Please see photos to help explain, but 2 of the walls have plate on the concrete foundation and 2 have for lack of a better term a small wall then the plate with joists on it. Any clue why this was done other that to save money? Also the small wall is insulated with fiberglass batting and covered with plastic. This seems to be leading to moisture and potentially mold issues. Any ideas what the plastic is there for? What is the best way to insulate this space, rigid foam board, spray insulation?
I'm no expert but sharing what I am doing. Using rigid foam r13 along studs exterior wall which is concrete. I used drylok extreme paint to water proof the porous concrete in my basement. It typically brings moisture in slowly but this should deter it. The 2" foam will act as my moisture and vapor barrier as well. The basement is typically controlled and should maintain fair temperatures. I am using drywall right on top with a 1.5" space between foam and drywall for breathing.