(Also see Substrates)
Cement board is a good choice for most installations of tile and stone on shower walls, tub walls and floors. It is important to install cement board in strict accordance to the cement board manufacturer’s written instructions.
Floors: Installation instructions for cement board on floors typically include applying cement-based thin-set between the exterior-grade plywood and cement board. The cement board is then screwed into the plywood while the thin-set is fresh/wet. MAPEI recommends the use of MAPEI Large-Format Floor & Wall Tile Mortar or MAPEI Large Tile & Stone Mortar as thin-set under the cement board. If leveling is needed on interior cement board floors, MAPEI recommends the use of a pourable leveler such as MAPEI Self-Leveler Plus over the cement board. MAPEI Primer T should be used to prime the cement board before the use of a pourable leveler.
Walls: Installation instructions to treat corners and seams on cement board on walls typically include using a self-adhesive mesh tape and thin-set. MAPEI recommends the use of MAPEI Large-Format Floor & Wall Tile Mortar or MAPEI Large Tile & Stone Mortar in conjunction with mesh tape recommended by the cement board manufacturer.