best underlayment for bathroom stone/tile?
We've recently noticed a crack running about 30 inches diagonally across the stone floor in our master bathroom.
Near the crack, there's another spot that seems to flex (and I can hear a faint squeak) if I step on the wrong spot. We hope to have this bathroom remodeled soon and want to be sure that the new floor is properly supported. It's on the first floor, above an unfinished basement level garage. My guess is that the large stone tiles were laid directly on the wood subfloor with no reinforcement or membrane used.
We'd like to have radiant floor heat installed during the remodel. What's the best way to insulate the subfloor so that the bathroom floor is warmed and heat isn't lost to the garage below? What should we expect the contractor to do to reduce the flex in the subfloor? Finally, we're thinking about going from stone tiles that are 18 in. to something much smaller. Can we do that and still have it look sufficiently upscale/on trend for future buyers? We don't know if we'll be here for just a few years or much longer, but need the house to be appropriate for its price.