How to: Fiberglass Shower Pan

Set the shower pan, without the drain, in the showering alcove and push it up against the framing walls. Mark the location of the drain on the floor with a pencil, then remove the pan. Cut a hole in the flooring at your mark, using a jigsaw.

Install the shower pan's drain. Place the top of the drain inside the shower base drain hole. Thread the lock nut onto the bottom of the drain from under the shower pan. Tighten the nut with a wrench.

Set the shower pan back inside the shower alcove. Push the pan up against the walls so the sides of the pan are even with the framing of the alcove. Line up the drain hole with the hole in the floor.

Check each side of the shower pan with a carpenter's level. Install shims as necessary under areas of the pan that are not level. Secure the shower pan to the framing walls by driving wood screws through the top lip of the shower pan and into the framing, using a screwdriver.

Push the PVC drain pipe through the drain hole from below with the help of an assistant. Slide a compression washer around the top of the drain pipe. Pound the compression washer and drain pipe back into the drain with a mallet.