I have a 1960s home built off the ground on piers. The bathroom floor is tile set in a 2″ thick grout bed. If I remove the grout bed, will I have a 2” gap under the wall plates? -Tom
Since your house was built off the ground on piers, there’s very little chance that the grout bed or concrete slab under the ceramic tile floor in the bathroom are supporting the walls. Typically, the walls were framed up as usual with the floor joists for a tiled bathroom set lower than the other joists to accommodate the thickness of a grout bed or concrete slab.
A wood or plywood subfloor was then attached to the joists and covered with felt paper. The grout bed or concrete slab was poured on top of the subfloor to bring the floor height up to that in the rest of the house. So the wall plates shouldn’t be left hanging in air if you remove the ceramic tile and grout bed.
After you remove the mortar bed or concrete slab, you’ll need to add additional framing to raise the joists up to the proper level, then install a plywood subfloor topped by cement backer board, followed by tile secured with thin-set adhesive.
If your old tile floor is in good shape without a lot of cracks or loose tile, and it won’t make your floor too high, you could tile over the existing tile floor (instead of removing it) using thin-set adhesive.
Before you start tearing up the old tile floor and grout bed, pick up a home test kit for asbestos and have the tile and adhesive tested. Some old tile and floor adhesive contained asbestos, and you don’t want to stir up those fibers unknowingly. It’s considered safe, however, to tile over a floor that contains asbestos.
Good luck with your project,