The standard shower is one of the wettest places on earth with the equivalent of 2,500 inches of rainfall a year. This means that properly waterproofing a shower is not just a recommendation, it is essential in protecting your home or commercial structure from the effects of water. Excessive water migration into wall cavities can cause expensive structural damage and invite mold growth which leads to illness and an unsafe environment.
Before even starting the process of waterproofing, it is important to prepare the substrate. First, make sure that the foundation is solid. The floor and frame must be built to industry standards. Then carefully plan drain placement to ensure proper water removal. In addition, check for level and pitch to create adequate drainage.
Contrary to popular belief, ceramic tile and grout, by themselves are not waterproof. Water can penetrate through cement-based grout and work its way through the substrate. To prevent water damage, you must install a waterproof membrane just below the tile bonding mortar as close to the tile as possible. There are two types of waterproof membranes, sheet and liquid applied options.
Sheet membranes are plastic or elastometric sheets that have to be bonded to the substrate before tile installation. Some sheets have adhesive backing and others require separate adhesives or cement mortar. Pressure-sensitive adhesive-backed membranes almost always require a primer be applied to the substrate. The primer may take an hour or more to dry. Other membranes must be bonded using a cement-based thin-set mortar which also takes time to cure.
When installing a sheet membrane, it is important to remember to treat and seal the seams where the sheets come together in order to maintain waterproofing. Pay close attention to all transitions and changes of plane to create a continuous waterproof membrane. Prefabricated sheet membranes are typically not as fast and easy to install as advertised. All components (membrane, preformed corners, bonding mortar, primer and sealant) must be gathered before installation can begin and the sheets must be cut. Sheet membranes are also more costly and require more labor and time.
Liquid membranes eliminate much of the hassle of installing prefabricated sheet membranes. There is no need for primers, no seams to treat and no worries about transitions up walls and through corners. RedGard Waterproofing and Crack Prevention Membrane is a ready-to-use, liquid applied elastometric membrane that creates a continuous waterproofing barrier with outstanding adhesion. It can also be used to effectively vapor-proof steam rooms and gang showers. RedGard can be applied by brushing, troweling, rolling and spraying. To assure a continuous film with no voids on the floor, apply a second coat over the first. Embed a thin fiberglass mesh into the membrane for changes of plane and for gaps 1/8” or greater for the best performance.
These are just a few of our recommended tips and tricks when preparing to waterproof a shower. For further details, read our Technical White Paper on waterproofing or view our Top Five Tips for Shower Waterproofing video.