Best practices for completing concrete pool interiors

Waterline tile

All concrete pools require some sort of tile or stone edge vertical border around the top perimeter. There are hundreds of tile options to choose from, including: porcelain, slate, ceramic, granite, and glass. However, not all are advisable to use in certain regions where frost climates exist during winter months. Geographical regions where bitter winter frost exists (northeast Canada and U.S.) versus non-frost areas (southern and southwestern U.S.) highly dictate the type of tile that is commonly installed by pool builders in those regions.

The vertical perimeter tile waterline serves two purposes:

1. Protecting the cement-based pool interior finish plaster (described later) that would be exposed to
   air and susceptible to unsightly cracking and/or delamination when not constantly hydrated.
2. To display the high-end detail that defines the elegance and prestige of a concrete pool.

Frost can damage the pool’s tile and interior finish, more so if the wrong tile and tile depth are installed; therefore, it is important to note, tile depth, as a standard, should be installed a minimum of 305 mm (12 in.) down vertically from the top. The option of continuing the tile further down is possible and recommended, but not necessary if proper winterizing techniques are used. Consumers are limited in their options when living in regions with yearly seasonal freeze-thaw cycles. When selecting a mosaic tile, it is important it has silicone backing dots (not a mesh backing) to ensure better bonding and a longer life.

When installing a larger tile, the act of back-buttering is important. Back-buttering tile is the process of applying, by trowel, a thin-set adhesive to the back of the tile prior to installation. Once the substrate wall has been combed with thin set, the back-buttered tile can be installed. Applying a wet thin set to the back of the tile, and on the substrate, minimizes voids where water and frost can travel through, reducing the possibility of premature failure.

In contrast, pools installed in regions that do not experience these seasonal freeze-thaw cycles require a minimum tile depth of only 152 mm (6 in.) since the water level is not lowered during the winter. This also means consumers in these regions have a wider selection of tile options (see Figure 1 below) to choose from as they are not limited to choosing frost-proof tile.

Thin-set adhesives

In any region, pool tiles should be adhered with latex modified thin-set adhesive to achieve the best results. Different adhesives should be used depending on the type of tiles being installed. For example, porcelain tile will require a different type of adhesive then glass tile. The manufacturer’s recommendations should always be followed when choosing adhesives as they are not all the same.

Tile grouts

When it comes to grout options, there are basically two types to choose from—cement or epoxy. Cement has been used for grouting pools for many decades and is described as the standard when pool tile is installed. It is economical to purchase and apply, and is still the most widely used for tile waterline on residential concrete pools.

Epoxy grout is a more durable option, however. This grout is waterproof and extremely resistant to chemicals. These added benefits come with a hefty price tag, as the materials and its application will often cost five to six times more than cement grout.

Commercial pools often have epoxy grout listed in the design specifications when the pool is being built due to its chemical resistance qualities.