We are converting our attached garage into a bedroom/bath. The current garage sits about 3' lower than the rest of the house's main floor. We are going to build the subfloor directly on top of current concrete floor (so it basically will rest on the floor).
My question is, how should I prepare the concrete floor for this? I planned on using a water proofing paint and then covering the floor with thick plastic to act as a moisture barrier. I would then lay 2x8 (to give myself enough spacing for plumbing) atop the plastic. I would like to be able to use regular lumber to stay away from pressure treated due to cost, but I didn't know if there was another "best" way.
plastic sheeting & p/t lumber's FAR less expensive & easier'n using epoxy coatings,,, there is NO paint that's permanent on conc,,, use sleeper 2x4's for better results,,, few like a cold floor against their footsies.
I am thinking of using a waterproofing paint on the slab, followed by 6 mm poly. Then I will add rigid foam insulation across the entire floor (attached to slab). After the foam I would add my joists ontop....I am considering using a ledger across one wall an inch or two off the flab to accommodate the uneven floor. Then run 2x8 or 2x10 joists with batt insulation in between. Would this be acceptable?
I know there's not paint that's permanent, but apply a waterproofing paint with stands 10 lbs of water pressure and I'm sure it wouldn't hurt to HELP keep additional moisture out. Regardless of whether i paint or not.....would the rest of what I describe work?