I am in the process of claiming garage space to use as living space in my home. The garage is attached to the house but the floor is about 6 inches lower that the slab of the main house. I intend on using 2x 6 pressure treated lumber to build the floor joists. I plan on isnsulating between each joist then put down tongue and groove plywood secured with liquid nails (or something like it) and screws. This should give me a sturdy floor. My real question is what type of insulation is best to use. Fiberglass like used in walls or the foam boards (not sure of the correct name) that are about 2 to 3 inches thick? Also do I need to lay a vapor barrier down before I start laying dowen the joists and the insulation? Any help/advise is welcomed and appreciated!