Cement board is the foundation for tile installation in a shower area. It provides the solid foundation that is required to prevent tile from shifting and falling off the wall. Cement backer board will not rot when exposed to moisture, making it the ideal solution for high-moisture areas such as a bathroom.
Staple a 4- or 6-mil vapour barrier to the studs around the shower to add protection from moisture to prevent the studs from water damage and rot. Tape the overlapping edges as needed with vinyl tape. The bottom of the vapour barrier is to go in front of the shower pan or slightly over a tub flange.
Measure the height of the shower area, floor to ceiling.
Measure the distance between studs. The pieces must fit on centres of the studs to screw the edges to the studs to hold them securely on the wall.
Cut sheets of cement backer board to these measurements. Measure and mark the length, and use a square to draw a straight line across the cement backer board. Score at the location for the cut with a utility knife, turn the cement board over and press down on the piece so it breaks along the scored line. Measure and mark the width needed to fit between studs on the centres of the studs, mark, score and break to cut the cement board to the necessary width.
Attach the cement backer board to the wall with exterior, corrosion-resistant screws. Place screws along the sides and top, spaced approximately 6 inches apart. If there is a stud in the middle of the cement backer board, install screws there as well, spaced about 1 foot apart.
Use a drill with an appropriate-sized drill bit to create holes in the cement backer board for pipes.
Tape the joints and corners with self-adhesive fibreglass tape. Coat tape with thinset mortar using a spackle knife.
Apply caulk around pipes to prevent water from seeping behind the cement backer board.
When installing in a shower, the cement backer board is positioned over the bottom shower pan.