How to Install Cement Backer Board in a Shower Stall

Updated February 21, 2017

Cement backer board is the product installed behind stone or ceramic tile. The cement backer board acts as a foundation for the tile that provides a stable substrate to keep the tile from moving or shifting over time. Since cement backer board resist rotting, warping, deterioration and moulding, it is an ideal material to use within bathroom shower stalls. Along with having simple carpenter skills, the installer must use a few common tools to place cement backer board in high-moisture areas such as shower stalls.

Secure 4-mil vapour barrier to the wall studs within the shower stall area with a staple gun, overlapping all the edges of the barrier by at least 1 inch. The vapour barrier will protect the wooden wall studs from moisture, reducing he risk of warping and mould.

Tape the overlapping edges of the vapour barrier down with vinyl tape.

Measure the area of the shower stall. Measure and mark the cement backer board to conform to the measurements of the shower stall area.

Score the marked locations on the cement backer board with a carbide-tipped utility knife. Run the utility knife over the score marks three or four times to make it easier to snap in two. Apply pressure from behind with your hands, on the score marks, to snap the backer board.

Cut pipe holes out of the cement backer board, using a hole saw equipped with a carbide tip.

Secure the cement backer boards to the shower stall area, leaving a 1/4-inch space between the shower pan and the bottom of the backer board. Hammer corrosion-resistant nails eight to 12 inches apart on every edge of the cement backer board, leaving a 1/8-inch space between the cement backer boards for expansion room.

Mix thinset in a small bucket according to the included directions. Fill the spaces between the cement backer boards with the mixed thinset, using a metal trowel to pack and smooth the thinset into the gaps.

Cover the 1/8-inch gaps between the backer boards with alkali-resistant fibreglass tape. Cover the tape with more thinset and use the metal trowel to smooth the surface to create a continuous surface for the intended tile.


Pure silicone caulk is also an option to use when filling the gaps between the cement backer boards.

Things You'll Need

  • 4-mil vapour barrier
  • Staple gun
  • Vinyl tape
  • Measuring tape
  • Carbide-tipped utility knife
  • Hole saw with carbide tip
  • Hammer
  • Corrosion-resistant nails
  • Thinset
  • Small bucket
  • Metal trowel
  • Alkali-resistant fibreglass tape
  • Pure silicone caulk (optional)
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About the Author

Rachel Turner has been writing professionally since 2000, focusing on gardening and home improvement topics. Her articles have appeared online at SlowTravel and in publications such as the "Arkansas Gardeners," "One Step Ahead" and "Writers Now." Turner holds a Bachelor of Arts in English from Arkansas State University.