Another simpler, but more expensive option is a complete acrylic shower stall kit. They are really quite attractive, simple to install, and reasonably priced. Most major plumbing product companies offer them—Maax, Lasco Bathware, and Swan.
If you still want to install a classy-looking tiled-floor shower stall yourself, you will have to understand a few simple facts about ceramic tile and the concrete slab floor below it. Neither one alone will be sufficient to direct all the shower water to the drain. Whatever water does not get to the drain will end up on the floor next to the shower.
Ceramic tile itself is a very hard, durable material ideal for flooring. The weak point is the grout and the grout/tile interfaces. Although a tile shower floor with its neat, uniform grout appears to be waterproof, in reality, it is not. Especially as the grout sets and ages, tiny fractures and pits can develop that will slowly leak water.
The key to a leak-free shower floor, over a slab or a framed floor, is a pan liner. This fits under the ceramic tile and runs partially up the side of the shower. Its purpose is to catch the water that penetrates the tile grout and direct it to the drain. You cannot expect the concrete slab floor to take care of this task by itself.
In the old days, plumbers used thin lead sheets to make the shower pan. Today, with modern plastics, you will find that 40-millimeter chlorinated polyethylene (CPE) plastic sheet is easy to work with. You will probably have to visit a professional plumber’s supply outlet to find CPE.
CPE feels somewhat like rubber and does not have memory (tries to straighten itself back out) like PVC sheets. This makes it much easier to fold around the corners and lap up the sides, about six to nine inches. PVC tends to want to spring back flat when you release it.
Don’t frame the shower corner lumber tightly together when building the stall. Leave a small gap to tuck in the excess CPE film where it gets folded in the corners. If not, it will lump up and not allow the sidewall cement backer board to rest flush against the framing.
Use a special plastic plumbing drain with a clamping ring for simplicity. Lay it over the drain hole. Cut a hole in the CPE liner small enough so that it overlaps the flange on the drain. This will allow the drain clamping ring to trap the liner for a sealed, waterproof floor.
If you have a router, rout a channel in the wooden shower subfloor so that the drain will be recessed with the film, level with the drain weep holes. This keeps water that makes its way through the tile and grout from just puddling up on the CPE shower pan at the edge of the drain. Be sure not to plug the weep hole with the cement base.
