As mentioned, you want to start by asking yourself where the tiled wall will be located. This is because the location of the tiled wall will influence the type of installation you will need, as well as, the type of materials. Usually, people tile walls in rooms or areas of properties that are moisture-rich, such as bathrooms, showers, mud rooms, above kitchen sinks (backsplashes), and the spaces behind bathroom and kitchen sinks. This prevents the production of mold growth, and preserves the property’s structural integrity. Once you determine, or consider, which room and wall will be tiled, you can better answer your next question regarding water exposure.
It is important to ask yourself whether or not the tiled wall will be exposed to water or moisture-rich conditions. For instance, showers and kitchen backsplashes are going to get wet and be exposed to water and moisture daily, whereas a tiled wall in the laundry room or vanity room may not. For areas that will not be affected or touched by water, you can simply move forward with your project and tile over the drywall using the proper tools and instructions. But if you are going to install tile over drywall in an area that will be subjected to water and moisture, you will need to add backer board first. Also called “cement board”, backer board goes between the drywall and the tile, and works as a barrier against moisture and water penetration. It is a waterproof material that comes in sheets, similar to drywall, and can be purchased at most home improvement stores.