is it like from the bottom: floor joist, sub floor, cement board, tiles? or what?
When you got plywood floor or any wood floor and you want install tiles, you have first install cement boards with liquid nail and screws.
You use a cement board any where you need tile . You install it atop the standard 3/4 wood sub floor. And to install it properly you apply a thin set to the sub floor and then nail or screw it down. NEVER is construction adhesive used to properly install cement board. Using thin set creates a full coverage and won t cause gaps. Any questions you can e mail me through my avatar and check my qualifications there. GL
