Tile is one of the most flexible of all shower materials because, unlike factory-made, cast or laminated units that are available in a limited range of sizes and shapes, showers made with tile can be built to any size or shape. As well, showers made with tile can be the most durable if built properly. Showers made with tiles and a factory-made base (or receptor), are also limited in size and shape and are not included in this article, which begins with all-tile showers.
Traditional Mortar Setting BedsLike any other construction material, there is good mortar and there is mortar of sub-standard quality. Assuming that a mortar bed is dense with a low relative porosity (compared to a mortar bed that is poorly proportioned, mixed, or applied), the issue is where best to locate the moisture management system - behind the mortar bed, or on its surface. Traditionally, a mortar bed’s cleavage membrane, installed to prevent moisture wicking from the fresh mortar and considered by some installers to be a “waterproofing” membrane, is located between the mortar bed and the wall or floor structure. In this type of application, a tar paper or plastic film membrane, if properly sealed and joined, can provide a moderate to good level of moisture management protection. A down side to this method occurs when an installation is not allowed to dry out between uses and the mortar bed becomes water-logged and a potential safe harbor for mold and mildew to invade.
Shower PansTraditional shower pans, made from lead, copper, or synthetic sheets, and joined to a clamping-type drain, have been the heart of shower construction for many years. In many areas, the clamping-type drain is the only acceptable drain for a shower stall, but a new type of drain, known as a bonding flange drain, is gaining acceptance because it does not depend on traditional setting bed mortar(Photo 4). In place of a pan or membrane, another method simplifies the process (at the expense of a limited range of dimensions and shapes) with a one-piece, watertight, ready-to-tile setting bed that incorporates a sloped floor, upturned walls, and an integral curb.(Photo 5)
Surface-Applied Membrane SystemsAn alternative method to protecting a mortar bed floor still requires the traditional cleavage membrane (needed for all unbonded mortar beds) to protect the fresh mortar, but once the bed hardens, moisture management is provided by a loads-bearing, surface-applied membrane made specifically for use with tile. Such systems are available in two forms: factory-made sheet that is laminated on-site(Photo 6); or a trowel-applied system composed of a reinforcing fabric and a liquid, paste, or gel (some systems may not require the use of the fabric) that is applied to surfaces on-site in one or more coats(Photo 7). The advantage of these systems is they isolate the setting bed from moisture, and limit penetration to the tiles, adhesive layer, and grout.
In addition to protecting mortar setting bed, surface-applied systems (depending on the brand) can be used to protect other suitably strong materials such as concrete, plywood, cement backer boards, and self-leveling underlayment. They can also be applied to most non-mortar, factory-made shower components such as benches, inset boxes, and sloped floors.
- Photos courtesy of Mike Mesikep and Paul Winn.
- Tiles courtesy Michelle Griffoul Studios
- Tile Redi pan: www.tileredi.com
- Schluter Kerdi system: www.schluter.com
- NobleFlex, Nobleseal TS: www.noblecompany.com
- ProSpec B-6000: www.prospec.com