How to Build a Shower Pan Curb

Cut and install 2x4s to form the base for the curb. Attach three 2x4s to the studs and floor joists at the shower threshold using 16d galvanized nails. This should be done at the point during shower pan construction when the subfloor is still exposed.

Measure and cut waterproof membrane to fit over the shower pan after the mortar pre-pan has been placed and allowed to cure. It should be cut to extend about 8 inches up each wall and over the curb, or 16 inches.

Lay and attach the waterproof membrane to the pan and curb. Use an adhesive suitable for the membrane material and secure the membrane to the underlying mortar. The membrane can be stapled to the walls and curb for additional security, but staples should only be placed near the top of the membrane on the walls and on the top and outer side of the curb.

Glue dam corners into the corners where the curb meets the wall.

Cut metal lath to fit over the curb.

Attach the metal lath to the curb. Bend it to fit tightly over the curb and nail or staple the lath to the underlying wood. Only place nails or staples on the top or outer side of the curb.

Apply mortar to the two sides of the curb. Use a trowel to pack mortar into the lath. Place a thin, straight-edged board on the top of the curb to use as a guide. Smooth away excess mortar and use a level to check for evenness. Allow this mortar to cure overnight before continuing. The top of the curb will be mortared later.

Install tile on the curb after the mortar bed and tile placement in the pan have been completed. Use a scoring tool and your hands to break tiles to fit the curb sides. The tiles for the inside should extend 1/2 inch above the unfinished top, while the tiles for the exterior should extend 5/8 inch above the top to allow for a slight slope. Trowel mortar on the curb and place the tiles on the sides of the curb, using a level to check the tiles for evenness.

Pack mortar into the space at the top of the curb and screed off excess mortar to make it flush with the tops of the side tiles. Let this mortar cure.

Install bullnose cap tiles to the top of the curb.

Grout, clean and seal all of the tile once the wall tiling has been installed.

Apply a bead of silicone caulk along all corners or joints in the shower.