In everything, there is a system. While individual pieces make up a whole, it needs one, solid purpose to make it work. The same way works when waterproofing shower areas.
Professional installers know that it's not the tiles or adhesives, or mortar or sealer alone, Waterproofing Direct states. There must be an outlined waterproofing plan to make the most out of these materials.
One complete shower system used is the traditional tiled shower assemblies. In this method, the base is the mortar bed installed in a slope position in the drain. Crushed stones surround the weep stones in the drain to avoid blockage. Then pan liner tops the mortar bed and clamps into the drainage.
The Tile Council of North America Handbook for Ceramic Tile Installation is a good source for traditional method, which is also known as a water-in/water-out system.
The sealed system is also an option made for the direct installation of tile. On the subfloor installed is a sloped mortar base with solid backing on the floors. Then on top adhered is a waterproof membrane that includes sheet products and may come with reinforced mesh at corners and joints and over the surface. Tile tops the membrane with a thin-set mortar.
It prevents moisture from getting into the mortar bed or solid backing. As a result, it dries completely in between uses and removes the possibility of mold growth within the system. This sealed system makes direct application of the tile possible.
A sealed system will need a special drain for this method. An example would be one with integrated bonding flanges. It has a design meant for waterproof bonded membranes.
Vapor-resistant products are also ideal to use, especially where there is steamed shower. Materials with water vapor permeance of 1.0 or lower are better in managing water vapor than those that simply meet the ANSI 118.1 standards.
Waterproofing seems to be an exercise in easy DIY method. It's not, especially with the factors above.