Build Problem-free Tiled Showers – On the House

Build Problem-free Tiled Showers

By on February 14, 2014
water proof shower

Unfortunately, many people don’t realize that tile and grout―even sealed grout―are not waterproof, so the moisture and water vapor inside a shower can seep through to the wall and floor structures. If these structures beneath the tile are not sealed with a good waterproofing membrane, moisture will collect in the wall and floor cavities, leading to mold infestation, which can cause health problems and costly damage.

Not all waterproof membranes, however, guarantee a mold-free environment. Membranes that are installed beneath the mortar bed, for example, instead of on top, dramatically increase the risk of efflorescence (crusty deposits), bacteria, and fungus growth. Others, such as trowel-on membranes, are very messy and can be difficult to apply evenly.

Materials and methods like the bonded waterproofing membrane system from Schluter-Systems or the Kerdi-Board system of waterproof polystyrene building panels make it easier than ever to build a tiled shower that will remain waterproof and mold-free.

Bonded Waterproof Membranes – Make Showers Waterproof Before Installing Tiles

Unlike traditional shower pan liners, bonded waterproof membranes are applied on top of the setting bed and walls, with the tile applied directly over the membrane with thin-set mortar. The primary advantage of the bonded waterproofing system is that water and vapor are not allowed to saturate the setting bed or enter the wall cavity, thus reducing the potential for mold growth in the system and the need for special backing materials. The KERDI membrane can be installed over virtually any wallboard material including standard drywall.

The membrane is applied using thin-set mortar to all wall, floor, curb, bench, and niche surfaces in the shower area. This process makes the area completely waterproof and ready for tiles to be installed.

Using a drain featuring an integrated bonding flange, such as the KERDI-DRAIN from Schluter-Systems, ensures a simple and secure connection to the waterproofing membrane at the top of the assembly rather than below it, which is where traditional drains connect to pan liners. By putting all waterproofing on top of the assembly, moisture is prevented from soaking into the mortar bed.

Another product that helps achieve a completely watertight assembly without a mortar bed is a prefabricated sloped shower tray made of expanded polystyrene (EPS). The tray simplifies the process of sloping the floor and eliminates waiting for the setting bed to harden. Once the tray is secured to the substrate, the waterproofing membrane can be applied immediately and then the floor can be tiled. In the past, homeowners intimidated by the challenge of installing a mortar bed may have compromised their vision of a fully tiled shower area by installing a solid surface shower floor. The prefabricated polystyrene tray makes it possible to have a beautiful tiled shower floor without building a mortar bed.

Barrier-free Showers and Linear Drains

Barrier-free bathrooms have exploded in popularity, offering homeowners an opportunity to create an oasis within their own home, with curb-free showers and custom building elements like shower seats and vanities. The use of linear drains dramatically increases the design options for barrier-free showers. Linear drains offer certain advantages over typical “point” drains. Shower bases must be sloped from all directions to point drains, therefore limiting tile selection to mosaics or other relatively small-format tiles. However, the shower base can be sloped on a single plane to linear drains, which enables the use of large-format tiles. Large-format tiles are by far the most popular option for floors. In barrier-free applications using linear drains, the large-format tiles on the floor can be continued into the shower enclosure, creating a seamless transition and furthering the open-concept design. Linear drains can be installed at various locations, including adjacent to walls and at intermediate locations on the floor. These open-concept bathrooms provide both flexibility in design, and when approached correctly, durability that ensures the beauty of the bathroom will stand the test of time.

Creating a Full Wet Room

Waterproofing must be installed in all areas subject to water exposure. The problem is that you can’t always predict where the water will go. What was once considered the “wet area” and the “dry area,” separated by a curb, has now become a “wet area” and a “drying area.” In other words, we have to consider moisture management in areas that we traditionally didn’t have that much concern about, namely outside the shower. Schluter-Systems recommends continuing the waterproofing throughout the bathroom, effectively creating a full wet room to protect against moisture inside and outside the shower area. With membranes such as DITRA and KERDI, wet rooms can be created easily and economically.

Approved Methods Lead to Leak-free Showers

Because of growing concerns about mold and moisture issues, care must be taken to ensure that tiled showers are installed using an approved method. The cost of cutting corners or missing a step in tiled shower construction can be substantial. Homeowners and installers must choose and closely adhere to the approved installation method that best suits their requirements.

Detailed installation instructions and technical information can be downloaded at or requested by calling 1-800-472-4588.

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