How to Build a Tile Shower Floor

Because of the extreme amounts of water a shower faces each day, tiling a shower floor is one of the most challenging tile projects. Mistakes can quickly lead to leaks into the structure below and extensive water damage. Tiling a shower floor is not for the novice to tackle, so evaluate whether you have the skills necessary to complete the project correctly.

  • 2-by-4 wood
  • 2-by-10 wood
  • Staple gun
  • Staples
  • Drain assembly
  • Thick bed mortar
  • Level
  • Mixing paddle
  • Grout float
  • Vinyl shower base membrane
  • Membrane solvent glue
  • Adjustable wrench
  • Fiberglass batts
  • Plastic sheeting
  • Masking tape
  • Plumber's tape
  • Stone threshold
  • Tiles
  • Grout
  • Caulk
Frame the shower. The subfloor should be at least 1 1/2 inches of plywood and the walls should be framed with 2-by-4s that are 16 inches on center. Cut 2-by-10s to the right length and use nails or screws to install them on edge at the bottom of the bays between each stud. Build a sill at the entrance to the shower by installing three 2-by-4s across the opening.

Lay 15-pound tar paper over the floor, stapling it down and trimming it around the drain. Place wire mesh to fit over the floor, stapling it in place with a cutout for the drain.

Mark the shower wall for the mortar floor so that it is pitched inward at 1/4 inch per foot to the center.

Make a batch of thick-bed mortar mix in a 5-gallon bucket by following the manufacturer's instructions. Dump some mortar onto the shower floor and press it against the subfloor with a grout float. Level the mud floor using the mark on the wall and the drain level.

Use a utility knife to cut a sheet of vinyl shower-base membrane to cover the floor and extend 6 inches up each wall. Do this after the mortar has cured overnight. Press the membrane down into the corners and staple the upper 1 inch of the membrane to the 2-by-10 blocking. Fold the excess in the corners into a tight fit and glue the pieces together using membrane solvent.

Attach the drain plate and rotate to lock in place. Replace the bolts and cut the vinyl membrane inside the drain using a utility knife.

Insulate the shower walls with fiberglass batts and coat the interior walls with plastic sheeting by lapping it over the vinyl membrane by 4 inches and tacking into place along each stud. Install backerboard over the walls to create a 1/2-inch gap under the backerboard.

Cover the strainer with masking tape that has been trimmed around the upper circumference for protection. Wrap the threads of the strainer with plumber's tape and screw into the drain assembly.

Mark the floor for the second layer of mud by marking at a level higher than the edge of the strainer with an inward pitch of 1/4 inch. Using a level, transfer the marks into a level line all the way around the shower.

Prepare an second batch of thick-bed mortar mix in a 5-gallon bucket. Dump the mortar onto the vinyl floor and press against the subfloor with a grout float. Use a flat trowel to spread the grout over the pan and slope it from the line on the walls down to the height of the drain assembly.

Allow the mud to cure overnight at minimum. Install the tile by placing the sheets on a layer of latex-fortified thinset. Once in place, set a beater board over two or more sheets of the tile and tap with a rubber mallet to ensure they are firmly set.

Cut a solid piece of stone to fit over the sill for the threshold. Use a 1/4-inch square notch trowel to apply thinset over the surface of the sill and set the threshold. Level the stone so that it is pitched inward approximately 4 degrees (or when the bubble of the level just touches the outside line) to make the water drain inward.

Grout the area once the tiles are in place using a latex-containing grout, which is more flexible and less prone to cracking. In addition, caulk all seams, corners and wall intersects to prevent water from seeping into areas behind the tile.

Tips and Warnings

  • When leveling the mortar mix, a 2-by-4 can be used to get the pitch right by keeping one end at the level of the floor drain and the other level with the mark on the wall.
  • Mosaic tiles are best because they will conform to the pitched surface required for shower floors. It is best not to use anything larger than 3-inch squares for your tiles.

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