Im building a guest cabin on cement blocks that sit on grade. 3 6x6 treated beams on the blocks then 2x6 or 2x8 studs perp. to the beams. The floor will be about 24 inches off the ground. Whats the best way to insulate the floor between the studs? Ive heard that an oreo of plywood, fiberglass then plywood again is best. This true? Keeping in mind rodents and Northern MN climate. Thanks!!!