I decided it was time to tear out the old vinyl floor in our guest bathroom and lay down tile. I've spent most of the day scraping off vinyl, but I've received a variety of suggestions on how to finish my floor prep (the folks at my local hardware store and tile shop all seem to have conflicting opinions). I have an OSB subfloor with a layer of 1/4" plywood on which the vinyl was installed. It looks like the ply was glued to the OSB, does that make sense?. Do I need to pull up the plywood and lay down cement board? I was alternatively told I could lay self leveling concrete down on the plywood and tile directly over that. I'm a little concerned about height. Appreciate the help in advance.

I've seen the question asked, but not answered. I am tiling a basement bathroom floor and heard from some to prep the concrete floor with a waterproofing product like Redgard. Is this necessary or even recommended? The floor is level and has no cracks so I am ready to go, as soon as I get a definitive answer about whether to apply :confused:the moisture barrier.