We took out our old ceramic tile floor in the kitchen and hall. It was in 2-3" of mud. Now we are down to the original plywood floor which is not level, soft in spots and high where some panels join each other. What do we do? Do we use self leveling cement and then put down 1/4 or 1/2 hardiback? Do we put down 3/4 " new plywood over the old, then 1/4 " hardiback? Do we need to pull up the original plywood and install new subfloor? HELP!!! Also when putting down new plywood do we lay it over the joints on the old plywood or match up the joints?