We bought a house this spring with detached garage, 20x23 with plywood floor. It's off the ground ~8-10" on one end and about 3' at the other end. Entire thing is insulated R13 walls/ceiling and a NG garage heater is in there for heat (previous owner used it as a shop).
We have turned it into a gym, and in the process of bolting down the squat rack found out that the floor is not insulated. I'm trying to find the best way to go about insulating the floor so that we can workout throughout the winter without freezing our rears off. Floor is currently primed (Kilz) plywood covered with 8mm rubber flooring. Shed has older windows that let in a fair amount of draft, painted plywood walls and open kraft faced insulation under metal roof.
I had thought about doing something similar to kraft faced R13 (probably warmer) under the floor, then foam board as a thermal barrier over the floor studs and cover with hardware cloth to keep the rodents out. Where/do I need a vapor barrier? If needed, would it need to go below the insulation between the insulation and the ground, or above the insulation, attached to the bottom of the floor studs?
I don't know much/anything about this so any/all info helps!