I have a 5-year old house in Minnesota with a full basement; the basement is concrete block. Inside the basement, the builder put in stud walls around the perimeter and insulated that with fiberglass bats covered with a plastic vapor barrier. However, the walls are offset from 1 to 4 inches from the concrete block walls and there is a Gap between the foundation sill plate and the top plate of the stud wall of, of course, 1 to 4 inches. The basement is heated and we run a dehumidifier. My question is should that gap be sealed and, if so, what is the best way to do it? There is no insulation in the rim cavity on the inside since there is rigid foam on the outside of the rim joist.