What's Cooking In The Shower Pan

The shower pan is conventionally speaking the waterproofing that is preventing any water that may get through the grout from getting out and damaging the walls and floors. Originally this was made with a lead sheet formed, folded and then soldered in the corners. This was then filled with a mortar bed that was given the proper slope and drain assembly. On top of that the tile was mud set and then finally grouted. I was still working on jobs with lead pans into the late 2000s, most people have moved on.

The most common similar item would be membranes made from plastic sheet. There are also liquid membranes which are usually used in multiple dwelling buildings with a concrete structure. These receive the usual treatment of a mortar bed and mud set installation of the tile. These are an improvement over the lead pan, barely, it doesn't require a trained lead beater someone that's hard to come by these days.

The latest trend is for pre-sloped dense foam boards pre-covered in a water proofing membrane. These are made by various companies, Schluter and KBRS being two. For a small shower the pan can be one piece, for a larger shower it will be multiple pieces that need a piece of waterproofing tape applied over the joint. Next the drain assembly is set into the pan with caulking or thin set. The tile is thin set right on top of the pre sloped pan.

Lastly and there are fully finished pans or bases. These are more like a bathtub. They can be made from enameled cast iron, acrylic, fiberglass, cast stone, quartz, and even solid stone. These are no longer the ugly fiberglass shower bases of the 70's and 80's, many have sleek designs with hidden trough drains. Some pans may not have that custom look but there are a lot of options. The main draw back is when building a single family home a custom size will be a cost premium, but for multiple family or hotels these are my go to. The volume discount on a large order even makes custom sizes worth while. No matter what I find this a preferable solution to a traditional shower pan. They are easier and faster to install and maintain which means less labor and time spent on both.

The most important thing no matter what solution you decide on is to give your pan a water test. After the pan is installed stop the drain and fill it with water near to the top of the curb. Measure the depth and let it sit overnight. Usually if there is a leak it will be visibly noticeable but still measure the depth again. Expect a small amount to have evaporated but if you have lost a quarter inch you definitely have a problem and if there is water on the floor or ceiling below you know there is trouble. Even a fully finished shower base should get the overnight treatment to make sure the drain is properly sealed.