How to Build a Mortar Bed Shower Drain

Cut a hole for the drainpipe through any construction or felt paper that is covering the subfloor. Use a utility knife to remove a small section of paper from the drain opening.

Glue the bottom piece of the shower drain into the drain opening so the flange rests on the construction paper or subfloor. Use PVC glue or a cement suitable for the drain material.

Stuff a rag into the drain opening to prevent mortar from falling into the drain during subsequent mortar layer construction.

Screw bolts partly into their positions in the bottom drain piece. This is not a necessary step but will make it easier to locate the positions of the cuts that must be made through the membrane later.

Place a sloped mortar layer in the shower. Let the mortar cure as directed and cover the pan and lower portion of the wall with CPE waterproof membrane or another type of waterproof membrane. Remove the rag from the drain hole after this layer is completed.

Locate, mark and cut holes in the waterproofing membrane for the bolts to pass through. Cut a hole out of the membrane for the drain opening.

Remove the drain bolts if they were placed in the bottom drain piece earlier.

Position the middle drain piece over the drain opening and bolt holes and install the bolts, tightening them firmly to create a watertight seal.

Attach the drain strainer piece to the drain. Adjust it so it extends at least 1 1/2-inches above the shower pan plus the thickness of any tile or finish that will be applied to accommodate the thickness of the mortar, metal lath and tiles.

Spread tile spacers over the drain's weep holes before using mortar to build up the shower floor.