How to Cut Shower Pan Liner

Lay the shower pan liner flat over the shower floor. Center the shower pan liner so that it spreads out evenly on all sides. Place a heavy item on the shower pan liner to keep it from shifting as you measure and mark.

Fold the shower pan liner over the shower's curb. The shower pan liner must go up the inner wall, over the top and down to the bottom of the outer wall of the shower curb. Draw a line at the bottom of the shower curb to represent the cut length of that side. Draw a line on each of the other three sides of the shower pan at a point at least 3 inches above the shower floor. Press the shower pan liner into the edges of the shower floor as you measure to ensure accurate measurements.

Draw a circle over the drain hole in the bottom of the shower floor. Draw X's over each of the bolts or bolt holes around the drain assembly. Make each X exactly as wide as the bolts or bolt holes underneath it. Draw an arrow facing the shower curb so you don't forget the shower pan liner's orientation.

Lay the shower pan liner flat over a work surface covered with a flat sheet of plywood. The plywood will protect the surface from the utility knife.

Cut the edges of the shower pan liner along the lines drawn in Step 3. Use a utility knife and a straight edge to keep the lines straight. Cut through the bolt X's drawn in Step 4. Leave the drain hole alone for now. Cut the hole once the shower pan liner is in place and the drain -- all but the hair trap -- is assembled and in place.