DIY: Installing a Backerboard Shower

Install a moisture barrier or waterproof membrane over the studs or existing drywall. Hold the barrier taut against the wall studs and staple it to the wood. If possible, use one single piece to cover the walls. If multiple pieces of barrier must be used, overlap the seams by several inches. The barrier should extend over the waterproof membrane secured to the pan and lower wall. Use an adhesive suitable for use with the specific membrane type or silicone caulk to secure the material from the walls to the lower membrane where they overlap. Place no staples where this overlap occurs. For additional assurance, dab a small amount of silicone over each staple that penetrates the moisture barrier.

Cut the backerboard as needed to fit the wall and accommodate any fixtures. Using a straightedge as a guide, score through the fiberglass mesh within the board using a utility knife. Snap the backerboard at this line and cut through the mesh on the other side to separate the pieces. For cutouts, score through the mesh on both sides of the backerboard and use a hammer to punch out the hole.

Place the backerboard against the wall studs with the textured side facing outward. Leave about 1/8-inch of space between all joints, including wherever the backerboard meets a different material. Use 1/4-inch wood shims to keep the bottom of the boards off the membrane on the shower floor.

Secure the cement backerboard to the wall studs using 1 1/2-inch galvanized roofing nails. Place the nails every 8 inches vertically along the length of the studs and pound nails in within 2 inches of each edge. Do not place any nails below the level of the top of the curb at the shower threshold or within the bottom 8 inches or so of the wall.

Fill the gaps between sections of backerboard and corners with thinset mortar

Embed alkali-resistant fiberglass mesh tape in the thinset mortar over all of the joints.

Cover the tape with thinset. Let the mortar cure before tiling over the backerboard.

Finish the surfacing as desired, typically with tiles or stone, once the shower pan has been completed. Use grout and sealant to treat spaces between tiles and seal all corners with silicone caulk.