If we recognize the premise that “water always wins” and the fact that it is the tile installer’s job to keep it where it belongs, it makes understanding the process of water management much easier. The term “prone” means “likely to” or “apt to” do something. Therefore, we will consider water-prone areas as those areas that are likely to see some amount of water and how to properly control that likelihood.
Another premise that we need to understand is that a tile installation is not waterproof in and of itself. That may sound unusual, but there are people who believe that tile on any surface creates a waterproof environment. This is not true, and the failure of the substrate material causes the tile to also be considered a failure when in actuality the tile may have had little or nothing to do with it.