Installing showers spells the difference between professionals who know what they’re doing and those who do not. In flooring installation a mistake can lead to something relatively minor, such as slight discoloration in the material, or something catastrophic, such as a total adhesive failure. But in shower installations almost any mistake can lead to a catastrophic result, especially when a waterproofing membrane is haphazardly applied or the floor is not pitched with a 1/4” per foot pre-slope.

Jennifer Panning, Artisan Tile, said it is critical for installers and contractors to always follow manufacturer’s instructions when working with shower components and when possible use the same manufacturer for multiple parts of the installation. “We prefer to use the same manufacturer for the entire shower system, waterproofing and tile setting.”

When working with niches, benches and other shower features, Panning recommends installers use products with which they’re most comfortable, whether that means framing the feature in themselves or using pre-formed products. “With all the advancements in products, pre-formed materials can be beneficial for less experienced installers.”

Kevin Fox, Fox Ceramic Tile, said installers should “first and foremost review and understand the installation methods as detailed in the TCNA Handbook. Secondly, if you are using a proprietary system, thoroughly understand the requirements. Most manufacturers have instructional videos to review.”

Fox said when installing a liquid waterproofing membrane, don’t assume you know what you’re doing as “every manufacturer will have their own requirements. Some require fabric to reinforce corners, and some require fabric throughout. One, two or more applications may also be required and minimum thickness of the liquid must be attained. A mill thickness gauge needs to be used to measure this. These usually are available from the distributor at no cost.”

 He also cautioned not to use a non-alkaline product to tape wall board seams. “Alkaline-resistant fiber must be used so it can be imbedded in a Portland-based mortar. This is not the [same] reinforcing tape that a gypsum contractor uses.”

According to Matt Sletten of Sletten Tile, always take the time to do a water test before the tile is installed. “You want to know that shower will not leak. If you have a pinhole anywhere, it only takes about 20 minutes for water to start seeping through. Read the instructions and the TCNA Handbook to be sure you know what you’re doing.”

He added to make sure all the products in the installation work together as a complete system. “For example, the drain system is going to dictate what type of waterproof membrane you’re going to use, and all your installation components have to work together. If you have just one incorrect component for the application, it will fail.”

Most importantly, Sletten stated, take the time to do the installation right. “If you are just starting out, find somebody you trust and pay them for consulting to help walk you through it the first time or two. Ask questions. It’s not just a matter of diluting somebody’s spaghetti on the dinner table when water starts falling from the ceiling. It causes mold issues and structural issues.”

Mark Pennine, Ardex Americas tile & stone installation systems technical manager, said to follow all instructions when working with a liquid-applied waterproofing membrane, “such as using a waterproofing mesh for all change of planes and corners. Always install the recommended material thickness and number of coats, and allow the membrane to dry for the recommended time before conducting a flood test. Also, check local plumbing codes to determine if the waterproofing membrane is approved as a shower pan.”

He added, “Most failures stem from poor installation practices like not installing the required thickness of material or not transitioning the waterproofing membrane on to the drain assembly with a drain mesh. The drain tie-in and the waterproofing membrane is the most important spot in the pan if proper pre-slope has been installed. Always place pea gravel or spacers around the drain to ensure the weep holes do not get clogged with deck mud.”

While pre-formed materials have their benefits, Pennine said he prefers installing fabricated marble or granite corner seats, anchored into the cement board with thin set. “When installed with the proper pitch and a neat bead of silicone where the tile meets the seat, they are fail-proof.”

Tom Plaskota, H.B. Fuller Construction Products technical support manager, said the shower substrate must be compatible with both the waterproofing system (whether sheet, roll-on or trowel-on) and the tile. Approved substrates include “cement backer board, fiber cement backer board, mortar bed, glass mat water-resistant gypsum backer board, cementitious-coated extruded foam backer board walls, fiber-reinforced water-resistant gypsum backer board, concrete or masonry. For a tub surround with no showerhead, water-resistant gypsum board is also approved.”

He stressed the importance of ensuring that tiles have 95% mortar coverage and natural stone has 100% coverage when installed in wet areas. “Especially when working with large-format tile, installers commonly make the mistake of using the ‘dot method’ of installation, putting globs or dots of mortar on the back of the tile rather than carefully troweling it. It does not create full substrate contact or proper embedding and may create voids behind the tile that collect moisture and potentially harbor bacteria.”

According to Duane Farley, Loxcreen Flooring Group’s Canadian national sales manager, when installing a corner bench in a shower, “ensure that the walls where the bench will be installed are reasonably square, and measure in the shower where the bench will be installed the desired height and width for the front panel of the bench – typical bench height is 18 to 20 inches.”

He noted the bench should be installed in such a way that “the proper slope of the bench surface is maintained. This step will prevent water from pooling on the bench.” Before installing tile, “ensure that all joints are filled with Prova Seal by applying a 3/8” wide bead to each panel-to-panel and panel-to-wall joint that forms the bench. Trowel excess sealant flat.”

Brian Maloney, MAPEI technical services representative, said installers should be aware of state, county and city building codes before starting on a shower and to know which materials can be used “in most common types of wet areas, according to the degree of water exposure.”

One common misconception he often hears is that tile, grout and sealers are waterproof products on their own, though they are not. Other mistakes he sees are: “little or no slope to the drain; penetrating or puncturing of the waterproof membrane with nails or screws when attaching curbs, benches, or cement boards; improper mortar coverage and improperly prepared waterproofing membrane; the wrong selection of tile or stone for a wet area; and failure to perform a flood test.”

When building a bench, the installer needs to decide whether to build it out of wood, cinder blocks or a pre-made high-density polystyrene, Maloney stated. “Block installations should be covered with a paint-on waterproofer that also must tie into the shower pan and wall waterproofing. A wood seat must first be covered with plastic sheeting which is stapled in place and runs down to the pan liner. A layer of 1/2” concrete board is then screwed onto the wood frame, then a liquid waterproofer is applied to the surface.”

When applying waterproofing, “make certain it is continuous from the wall, over the top of the bench, and down the face of it, also making sure the top is sloped toward the drain. If there is any wood it needs to have waterproofing over it and the waterproofing needs to tie into both the floor and wall membranes.”

According to Tim McDonald, Merkrete vice president of sales, liquid-applied waterproofing membranes are very forgiving products. “Even if you punch a hole in it, you can apply more and it will dry monolithically again. These products have a tendency to be user-friendly.”

One misconception he sees about the product’s application, however, is that “a little is good and a lot more is better. But when you build it up too much it will take a long time for the membrane to cure, and it could emulsify in a flood test. Make sure to follow the instructions and allow plenty of time for proper curing.”

One advantage of liquid-applied products is their ease of use, he added. “When you’re building a feature like a bench or niche, liquid-applied is easier than a sheet membrane because you can take that liquid and apply it at any degree and in any turn. With sheet that becomes a little more complicated when working with cut-outs, seats and footrests.”

Sean Gerolimatos, Schluter Systems technical director, said installers should not only be familiar with manufacturer instructions and the TCNA Handbook when tackling a shower installation, but also “take advantage of education and training opportunities. For example, Schluter Systems has an entire series of installation videos on our website and YouTube, and we run training sessions and workshops for professional installers regularly.”

He noted common mistakes when installing tradition pan liner systems include “ignoring pre-slope installation, plugging drain weep holes with mortar, and fastening tile backer boards through the liner, on or below the curb. Leaving out the pre-slope and plugging the weep holes will cause the mortar bed to remain saturated, increasing the risk of efflorescence and mold growth in the system. Penetrations through the liner on or below the curb will result in leaks that damage surrounding building materials like wood framing and gypsum board ceilings.”

Jeb Broomell, USG product marketing manager, tile & flooring, recommends a shower system with all the components from one manufacturer. His company’s Durock Shower System features “a pre-sloped tray, one-inch at the perimeter, guaranteeing a proper, comfortable slope. When applying the included waterproofing membrane, it is critical to ensure the two-inch overlap of all membranes, banding and pre-formed corners, which are all part of the system.”

He added that pre-formed benches and niches are also available as part of the Durock Shower System in multiple sizes. “Additionally, the pre-formed benches can be cut to virtually any size or shape to accommodate any jobsite.”