Of all the different designs that are available for shower replacements, there are really only two basic types: those with a shower pan, and those without. Showers that lack a pan are generally of the one-piece fiberglass design, and simply slide into the place of the old assembly, after which the shower valve and drainage can be hooked back up. Showers with pans are the tiled type, usually from top to bottom. These showers are far more attractive and can be tailored to
suit almost any custom or creative design the homeowner might want to implement. However, one simply cannot stand on the shower's tile floor and expect to be supported just by the tiles themselves. Under the tile is a cement/mud mixture that hardens into the base for the shower. In the middle of this base is the shower drain. Under these items in the shower pan itself. In older homes the pan was constructed of lead due to its soft and pliable nature. In current construction, shower pans are made of a vinyl material that is easier to work with.
Shower pan constructions begins with stripping away all of the tile and cement base mix from the old installation. The older lead pan is removed, and the area is thoroughly cleaned. The new pan liner (the vinyl) is then laid in place, covering and wrapping over the lower ledge of the shower stall, to a minimum of four inches high. The front ledge (the step-in) is then wrapped, and all the edges are glued with a special bonding agent that seals the shower pan liner and prevents leaks. The shower drain is inserted into the center of the pan, and is a two-piece affair that clamps down on both the underside and the top of the liner. The new drain is then stubbed up and the cement mixture is poured into place and allowed to harden. The new shower can now be tiled and finished.
This is, of course, and over-simplified summary, and the actual installation takes the better part of a day. As always, the work is fully warranted against leaks. These types of shower pans generally last many, many years.