“…Since we know that the tile itself does not create a waterproof environment, additional measures need to be taken as part of the installation process. For the most part, the tile surface, either glazed or unglazed, does repel water, but other than a porcelain product, the body of the tile is absorptive to some degree. The only way to stop the movement of the water absorbed through the grout joints and into the tile body is to provide a positive water barrier behind the tile, while also providing a load-bearing capacity.

The application of a waterproof membrane is an excellent way to segregate the water from the substrate. These products come in three basic categories — liquid, trowel-applied and sheet — and they are designed to accomplish three objectives. The first is to bond tenaciously to the surface, which is being protected. Second, the membrane must allow the mortar or adhesive to bond adequately in order to support the weight of the tile products being installed. And third, it needs to prevent the water from entering the substrate efficiently and effectively…”

Read more about waterproofing membranes below:

“Installing tile in wet areas”

Tile Magazine
July 1, 2013
By: Scott Carothers

http://www.tile-magazine.com/articles/87396-installing-tile-in-wet-areas