How to Make a Custom Size Shower Pan

Layer the floor of your shower stall with roofing paper and steel mesh. Staple both to the floor with a heavy duty hand stapler. Remove the paper and steel mesh from over the drain opening with metal cutters and a razor. Bolt the bottom flange of the drain into place inside the drain hole with a wrench and the bolts that come with the drain. Do not install the top portion of the drain just yet.

Mortar over the steel mesh with sand mix cement (cement and washed sand) and a trowel, creating a 1-1/2-inch thick bed that slopes gradually towards the drain. Measure the slope with a carpenter's level; a reading of 1/4 bead off center or more is recommended. Let this dry for 24 hours.

Lay down the shower liner in the shower stall over the mortar bed. Staple the liner to the framing around the shower and up and over the curb, if your shower has a curb. Cut a hole over the drain. Set the top of the drain on the bottom flange of the drain and bolt the drain in place with the mounting bolts and wrench.

Mortar over the shower liner with another layer of mortar. Trowel the mortar into the bed and smooth it out with the flat bottom of the trowel. Follow the slope off the first layer. Let the mortar dry for 24 hours.

Install drywall on the surrounding shower frames with drywall screws and a screwdriver. Tape the seams and finish with joint compound and a scraper. Apply tile mortar to the dried shower bed, and install the tiles. Continue to mortar and tile the surrounding drywall once the joint compound is dry (usually between 10 and 24 hours depending on climate and humidity).