I recently purchased a home (built in 1928, located in the northeast US) that has a side entrace foyer converted into a bathroom. The house is on a hill and the floor of the bathroom stands 8 feet or so off the ground (bare dirt) and is completely uninsulated. The area below the floor is open to the outside and used as outdoor storage space (it is walled on 3 sides). I am a complete newbie and have found some information on the web, but much of it is conflicting or not completely applicable to my situation. My question is, what would be the best way to insulate the floor of this bathroom? Thanks in advance.
Use fiberglass batts between the floor joists, placing the kraft paper up against the floor. R-19 is probably the right thickness for that application. Then cover it up with something like OSB or plywood to hold it in place, and keep the wind out of the insulation.