How to Build a Shower Floor Curb

Measure the distance between the walls of the shower to determine the span of the floor curb. Cut two identical 2-by-4-inch boards to the measurement using a handsaw. These boards form the structure of the curb.

Set the boards on top of each other to form a wood block or wall. Ensure the ends of the boards are flush with each other. Place this block over the shower floor, between the walls. Drive roofing nails through each corner and the center of the block to secure them to each other and the floor directly below.

Measure the dimensions of the back, front, top and sides of the wood block. Wear thick gloves and cut the sheet to the size you need using tin snips. Pre-shape the lath so it fits snugly over the wood block. Use the straightedge or 1-by-4-inch board as a guide to bend the lath into a U-shaped sheet that fits snugly over the wood block. Repeat the process to cut and bend as many sheets of lath as needed to cover a long curb.

Install the preshaped lath on the wood curb. If using more than one sheet, overlap the edges of each subsequent sheet by 2 inches. Insert evenly spaced staples into the lath along the front, or outside, of the wood curb.

Prepare mortar in a bucket or wheelbarrow according to the manufacturer’s directions. Use a trowel to scoop some mortar and apply it over the top of the lath-covered curb, forming a 1-inch-thick layer. Continue to apply mortar over the top until the lath completely covered.

Place a 1-by-4-inch board or straightedge over the mortared top of the curb. Position the board so its front edge extends the curb by 1/2 to 3/4 inch.

Scoop mortar and apply it over the wood block along the front, forming a 1/2-to 3/4-inch-thick layer. Fill the gap along the protruding side of the straightedge with mortar.

Press the straightedge on the mortared top with one hand and scrape the mortar along the front of the curb with the other to smooth it out. Use a flat trowel to smooth the mortar. Move the straightedge over the back of the curb, ensuring it extends that side by 1/2 to 3/4 inch. Repeat the process to pack the gap with mortar and smooth its face.

Apply an even layer of thin-set mortar over the back of each tile before laying it over the front and back, and then the top. Use a notched trowel when spreading mortar on the back of the tiles.