A vented garage attic shares a living space and the unconditioned garage underneath. A bedroom partially above the garage and partially above the living space has knee walls in this attic. The attic floor above the living space currently has cellulose and nothing above the garage. The knee walls have fiberglass insulation and a vapor barrier on the outside. There is an empty space where the knee walls meet the attic floor and hot air gets in between the bedroom and attic floors. I saw fiberglass batts inside this subfloor. I am trying to find the best way to insulate the bedroom and the living space. Area is Northern Virginia.