Building a Waterproof Ceramic Tile Shower Ceramic tiles need a system to ensure that water doesn't cause damage.

By Stacy Hunt There's something about a tiled shower that speaks to the homeowner looking for a luxurious retreat from daily life. However, beauty aside, it's a basic fact of construction that ceramic tile installations by themselves aren't waterproof, just water-resistant. To be used effectively as a surface in the shower, ceramic tiles need the help of a good, waterproof system to ensure that water doesn't penetrate to the subfloor and cause damage. The most common issues in ceramic tile shower installation come from assuming waterproof properties of materials that are not waterproof — green board, mortar, grout and tile — and building an ineffective drainage system behind the tile installation to direct water away from subfloors and framing. Here are some key things to pay attention to while installing ceramic tile showers to create a beautiful and functional finished system: General Make sure your work surface is level, and take all precautions to prevent tile from cracking, as discussed here. Create a good drainage plane. Make sure that all water from the shower is directed across waterproof surfaces, into a waterproof shower pan, and through a waterproof drain installation. Gaps and goofs cause water intrusion — and problems. Focus on areas where different surfaces join, such as windowsills and where backerboard meets shower pan. Use the right backerboard. Select a backerboard, such as cement backerboard or fiberglass-coated gypsum board, that's waterproof and not just water-resistant. Don't use green board. It can get wet, doesn't dry, and is against code in most places. Use waterproof mortar and grout, and make sure that homeowners know how to maintain it. Shower-Pan Liners Use an appropriate shower-pan membrane liner, made of polyvinyl chloride (PVC) or chlorinated polyethylene (CPE), and install it correctly below the mortar and tile to funnel any water that may leak through tile and grout to the shower drain. PVC liners are less expensive than CPE and provide a more professional surface, but are slightly more rigid. Be sure to use the correct bonding adhesive for your choice of liner. Be aware of the weepholes in the drain and make sure not to block them with your liner or get them gummed up with construction debris during installation. To ensure that water doesn't pool, slope your shower bed toward the drain using a layer of mortar under the shower pan liner. Plumbing code requires a slope of 1/4 inch per foot. Specialized pan liners can be purchased that create the slope for you, such as this one from Dix Systems. Lap your shower liner at least 9 inches up the framed wall and secure appropriately. Never allow a break in the pan liner. Use a special solvent to join two pieces if more than one piece must be used, and the liner must be attached outside of the drainage plane (i.e. lapped over a shower curb and attached on the outside). Consider using a prefabricated shower system, like those commonly used in commercial applications (such as hotels and apartments). The systems, like this one offered by Schluter Systems, provide everything you need to create a waterproof system, including the shower-pan assembly, waterproofing membrane and vapor retarder, drain system, trim pieces and edge protection. Tiled showers can add beauty to any bathroom and new products, and prefabricated systems and a bit of extra planning can help ensure years of durable service. Stacy Hunt is a freelance writer and consultant on building science and green building. She is the former business manager of BuildIQ. RELATED ARTICLES: Types of Membranes for Tile Installations Backerboards: Properties and Installations Installing Tile Surfaces That Won't Crack Choosing the Right Substrate