Installing a new fiberglass shower pan can be done by most homeowners who have some mechanical ability. Probably the most challenging aspect of this task is making sure the existing shower pan drain and the new shower pan drain hole align when the new pan is installed. Next comes the securing and tiling around a new shower pan, but this is the easy part. Most, if not all, shower pans come with the hole centered in the pan and are constructed so that water flows naturally to it and down the drain. This hole is designed to fit the existing drain.
Step 1: Measurements
Carefully take measurements to decide where the exact center of the shower pan drain hole is located. Next, carefully measure the area where the shower pan will sit and determine if the shower drain is located in the exact center of where the shower pan will sit. This alignment is crucial and the most important part of this task.
Step 2: Sub-Flooring Considerations
Unless the shower pan will be sitting on part of the concrete slab of the foundation, make allowances for it to be set down on a level surface. This can be plywood, sand or plaster. Use a long liquid level to ensure the base is as flat as possible.
Step 3: Shower Pan Clearance
Make sure there is adequate clearance to move the shower pan within the enclosure so that the shower pan can be placed exactly above the shower pan drain. Slowly lower the shower pan over the drain pipe. The edges of the shower pan should fit snugly against the shower stall 2x4s. Slip a washer over a #8 wood screw, approximately 1 1/2 to 2 inches long and secure the base into several of the surrounding 2x4s.
Step 4: Drain Assembly Hardware
Several applications of drain assembly hardware are used to secure the shower pan drain assembly to the shower drain plumbing. Most call for the use of a silicone sealant applied with a caulking gun around the shower drain assembly. Apply this sparingly and wipe away any excess. Next, secure the drain locking ring, rubber assembly and tighten by hand. Be careful not to over tighten this assembly.
Step 5: Install Wallboard and Tiling
Let the silicone for the drain assembly set for at least 24 hours before continuing to work on the shower pan. Using the cardboard that the shower pan came in, tape pieces of it to the shower pan so that it does not get marred or scratched while tiling. Begin by placing the hardy-board around the shower pan extending it over the lip and to the top of the pan boarder. Secure the board with drywall screws and be sure to countersink them slightly.
Apply a generous coat of tile mortar to the base of the wallboard and work up and away from the shower pan. Begin attaching tiles to the mortar at the base and a corner of the wallboard.