How to Make a Dam at the Front of a PVC Shower Pan

Prepare the site. Remove any materials necessary to expose the wooden subfloor.

Measure the opening at the shower threshold. The curb should be placed between wall studs and over a floor joist.

Cut three lengths of 2-by-4 to fit the opening at the shower threshold.

Stack the 2-by-4s in the shower threshold and attach them to the floor joist and wall studs using 16d galvanized nails.

Measure the shower floor and transfer these measurements to the PVC membrane liner. Add an additional 8 inches for each of the shower walls and as much distance as needed to go up, over and down the face of the curb.

Cut the PVC along the marked measurements and place it in the shower. If desired, reinforce the drain area by gluing an additional circle of membrane 2 inches larger than the drain flange to the top of the membrane already over the drain.

Apply PVC adhesive to the area around the drain and press down to secure the PVC membrane. Work from the area around the drain outwards to the wall, applying the adhesive and pressing down to free air trapped under the membrane until you reach the walls.

Fold the extra material at the interior corners into a flap. Hold the material for one of the side walls against the wall and press it into the corner and along the next wall so that the corner is covered by a solid portion of the membrane and the flap is created on the back wall.

Glue the side wall and corner in place. Apply glue to the inside of the created flap and press it into place.

Staple the flaps and the rest of the membrane in place. Place staples only near the top of the membrane -- all staples must be above the top of the curb.

Cut the membrane for the curb along the stud so that it can be folded over the curb.

Fold the excess corner material for the curb so that the flap extends over the interior of the shower and glue and staple it in the same manner as the flaps for the inside corner.

Glue curb corners to the inside of each corner of the curb.