The purpose of a shower pan is to collect water from a shower. It is designed to catch water that permeates a tile floor and direct it into the drain pipe. The so called “pan” is really an impermeable liner material fashioned under a concrete base.
They are often interchangeably called a shower pan, shower liner, shower pan membrane, waterproof barrier, shower base, shower tray, or shower receptor. Yet technically, each has a different meaning depending on the context and each available in a variety of materials.
How to Install a Shower Base Pan
If you are contemplating installing a shower pan yourself in a new bathroom or shower without the help of a professional, you can do it, but it is critical that it be done carefully and correctly. You should choose the strongest shower pan material available; this is to make sure it will not leak or allow any moisture into the surrounding drywall. Shower pans have been made out of various materials in the past, including lead and other metals.
Today, while other flexible waterproof materials may readily be used, such as rubber matting, fiberglass resin compounds, PVC (poly-vinyl chloride) is perhaps the most durable. At a thickness of 40 millimeters, a flexile or pre-molded PVC pan won’t rot and is virtually indestructible. A pre-molded or structured liner is easier to install than a custom made flexible liner pan.
Ceramic Tiled Shower
The old way to make is a shower is with a mortar bed. This method is quite tedious and involves a mortar bed, framing a base, and correctly sloping the floor to the drain. Only then can you start laying tile, grouting and so forth.
If you are creating a ceramic tiled shower, it is recommended that you build a “curb” around the sides in the shower floor with 2 X 4s, with the 4 inch side down. This is to allow your material to run up the wall about eight inches underneath your wallboard, to a point slightly above the top of the curb. This is necessary as ceramic tile walls are not waterproof, only water-repellent.
You then will need to buy enough mortar mix (sometimes called “mud”) and mix enough of it to evenly cover the surrounding area that the pan will be covering. You need to spread your mortar very smoothly on the area so that there are no lumps. Lumps could result in your floor having weak areas.
Pre-formed Shower Pan
With a pre-molded or structured shower pan, the actual slope that is required is already actually built in the pan. Most now come with built-in curbs as well. You just need to fit the preformed pan into it’s framed-in base and apply some mortar to the bottom and a bead of adhesive to the curb.
If using a ceramic tile shower floor, ensure that you allow for the full thickness of the tile, grout and mortar so that the top of the finished tile is the same height as the drain.
Preparing the Subfloor
Assuming the choice has been made for a pre-formed shower pan:
The first step is to prepare the subfloor. The sub-floor must be level and free from debris. To ensure a level floor, check the floor with a long level. Using the template provided, place the template on the floor and confirm that the drain is in the correct location.
Set the pan up on saw horses or any raised platform that allows access to the top and bottom. Use rubbing alcohol on the drain opening with a clean rag. Around the drain opening apply a generous bead of 100% silicone. Insert the metal drain assembly into the drain hole and press firmly into place.
Make sure that about a 1/8” space exists between the pan flange and the studs. With the level, confirm that the pan sits flat on the floor. If shimming is required, lift pan and place shimming material where required.
Lower the pan into place and check for level.
Apply silicone caulking on the underside in your shower pan and additional silicone around the drain opening in the sub-floor. Connect drain pipe to the drain assembly (details not provided here).
Finally, let your shower pan set for a minimum of 24 hours to allow the silicone to properly cure. At that point, the wallboard and tile can be installed.
Replacing a Shower Pan
Replacing a worn shower pan is, of course, an even bigger job. Yet a new and sturdy one will increase the life of a shower and prevent water damage to the surrounding walls. Replacement of an old shower pan is an option if the shower was built of mortar, rather than drywall.
Otherwise the entire shower stall would likely need replacement. If your shower has nothing more than sheetrock behind the tiles, this would be a good opportunity to completely rebuild it properly.
Photo by Barron Fujimoto; Creative Commons Attribution-NoDerivs License