How should I prepare a sub-floor for porcelain tile?
wirelath nailed over the plywood(overlapping the lath 2",use paper backed lath to avoid moisture of setting/grout materials)nail or staple(pneumatic,not a hand staple)in a 8"x8" grid.wire acts as a trampoline,the thinset gets into the mesh but won't twist when the plywood deflects.normal thin-set is fine in the application(unless a modified is needed for the tile).