For years, fiberglass pools had the public perception as being the less-sophisticated option in the bunch. The idea of having a luxury pool leaves most customers thinking about concrete and sends them searching for their local shotcrete builder. But such assumptions couldn’t be further from the truth when it comes to these pre-molded products.

“With fiberglass pools, we can pretty much do what anyone else does with any other pools,” says Russ Hinderliter, co-owner of San Juan Pools & Spas of Pekin, Ill. “We’re doing some very nice projects. The only thing I’m limited in is dimensions.”

What often sets a shotcrete pool apart from its fiberglass cousins is the details. Tile work elevates the look of concrete pools, motivating more fiberglass projects to include these elements.

A trend has been emerging among fiberglass pool builders and manufacturers to go even beyond the waterline, with tile extending over the lip and onto the decking, a design strategy meant to highlight features on the fiberglass shell and surrounding areas.

Here, professionals explain how to choose tile and apply it to fiberglass shells.

Why consider it

There are two reasons to add a tile line to a fiberglass pool — aesthetics and function.

“I personally don’t think a pool looks finished unless it has ceramic tile on it,” says John Anderson, president of Anderson Pools and Spas in Murfreesboro, Tenn.

At his company, tile and coping are included in every pool package. In fact, picking out the tile is one of the first decisions a homeowner makes. To help them, Anderson’s showroom includes a tile display with types grouped by price range.

Beyond enhancing a pool’s look, a tile line can help prevent wear on the shell. Water can leave a scum line around the pool, and some professionals have more confidence in tile to hold up to the scrubbing needed to remove the build-up.

Tile choice

Adding tile to a fiberglass project, though, usually serves purely aesthetic purposes and helps make a fiberglass bid more competitive against other types of pools that regularly include such features.

But recommending tile to customers also has challenges to consider.

First, the size of the tile is very important. “[Some] beautiful tile may not fit on the curves and contours in the fiberglass swimming pools,” says Bob Ault Sr., founder of FSP Inc. in Lecanto, Fla.

The smaller the tile, the easier it is to apply to the shape of the shell.

Ault, who has installed tile on fiberglass projects for more than 40 years, discourages patterned pieces exceeding 2 inches in width. “That seems to be the magic number that will wrap around the curves and contours and still be relatively flat along the sides of the pool,” he says.

Larger tile can be used in certain shapes of fiberglass pools, but the smaller the tile, the easier it is to apply to the contours without cutting.

“The large majority of the tile we use is 2-by-3, 2-by-6 or 3-by-3 inches, because you can’t make it go around the curves with a 6-inch-[wide] tile,” Anderson says. “But if it’s pretty straight lines, 6-inch works fine.”

Builders also should be cautious while applying tile that has a pattern or direction to it. It’s not uncommon for a piece to be installed incorrectly or out of pattern order.

“On some tiles, the pattern is such that you have to make sure you place the tiles properly all the way around the pool,” Ault says. “Otherwise, there will be interruptions in the pattern. It won’t be the same all the way.”

Prepping the surface

Tile application techniques may vary from builder to builder, but the basic steps remain the same among all professionals: Surface preparation, adhesive application, and affixing of the tile.

As with a tile job on any type of pool, surface preparation is a make-or-break proposition.

“Laminating things on top of something else, you just have to be very cautious, so the prep work is very important,” Hinderliter says. That includes sanding before applying the silicone and tile, and ensuring the surface is clean and free of dirt or other particles that can interrupt adhesion.

At Anderson Pools and Spas, crews begin by sanding the fiberglass surface with 60-grit sandpaper in an area matching the width of the tile that’s going to be applied.

If a builder doesn’t want to sand, though, there is another way. Decades ago, Ault experienced some failures in his tile jobs resulting from sanding debris interfering with adhesion. So he ran tests in a lab to determine whether sanding was necessary. He found no advantage to it.

Instead, he prefers to wipe the surface with a solvent or alcohol before applying the tile.

When it comes to setting at the waterline only, the experts recommend installing the shell and filling the pool most of the way before applying the tile. A fiberglass install is usually level to within ½ inch or less, but that still leaves room for error. Using the waterline as a guide for placing the tile allows the builder to always have a level job.

When applying heavier tiles or to ensure a straight bottom edge, Anderson recommends using a product commonly found at the hardware store: weatherstripping.

“Sometimes we have to put a piece of weatherstrip around at the bottom of the tile for it to rest on so it doesn’t slide until the silicone sets,” he says.

In his years working with tile, Ault has picked up a trick for installing and removing the weatherstripping without leaving residue on the fiberglass shell.

“I’ll take ¾-inch masking tape,” Ault says. “I put that all around the pool, then I put the weatherstripping on top of the tape. Now when it’s time to remove it, … everything comes off with no mess on the wall.”

Adhering the tile

Hands down, silicone is the winner for applying tile to a fiberglass shell, these veterans agree.

Through trial and error, they each have found their favorite product among the hundreds of silicone formulas available on the market.

For instance, Anderson prefers Dow Corning 799. “There are a number of those on the market that would be fine, but that’s what we use,” he says.

Ault, after years of trying brand after brand, developed his own proprietary silicone formula to attach tile to fiberglass.

He recommends one of the several formulas specifically geared toward application on fiberglass. He suggests that contractors search past the obvious outlets to find the product that makes the best fit.

“Almost all consumers and also most contractors are only aware of one silicone: that’s the product sold in a hardware store,” Ault says. “There are at least 2,000 silicone rubber formulas. … Silicone can be formulated for almost any purpose.”

When it comes time to set the tile, installers can put the silicone on the back of the tile or to the shell itself. Either way, remember that silicone is quick-drying, so installers should apply it as they go.

Whether or not to use grout is a matter of builder preference (see “To grout or not to grout,” page 50).

Ault recommends using silicone grout because of its longevity of wear and resistance to fading, cracking, and coming out.

It’s true that the portion of tile that continuously sits underwater likely will delaminate over time. But the dry side will stay put, and the grout will keep the bottom half in place.

“You will not know the adhesive has let go behind the tile... because the grout won’t let go of that tile for any reason,” Ault says.

The cure time for silicone grout is very short, so only apply half a tube — 3 or 4 square feet — at a time, and clean it off before continuing on with the job

For his tile lines, Anderson prefers a groutless installation, and instead places the tiles tightly side-by-side.

“I ask every customer: ‘Have you ever cleaned the white grout lines in a tile shower?’” he says. “That’s a real scourge.”

But without grout, there can be alignment problems, so keeping the tile vertical can be an issue.

“If it gets out of vertical … immediately correct for it by leaving a very tiny bit of space between the tiles that doesn’t show,” Anderson says.

To grout or not to grout

When installing tile onto a fiberglass pool, the question of whether or not to grout pops up.

There are arguments for and against.

Some say that, with the right grout, this step can add longevity to the tile and make upkeep and repairs easier.

Bob Ault Sr., founder of Lecanto, Fla.-based FSP Inc., recommends performing this step — with a rubber silicone grout. It just helps everything stay put, he says.

“This grouting material permanently adheres to every tile and its neighbor and goes through the grout joint and adheres to the substrate, holding everything in place on the wall,” he says.

But John Anderson, president of Anderson Pools and Spas in Murfreesboro, Tenn., says his crew never grouts their tile. “You can’t have rigid grouts joints in it, because the wall’s flexible and as the temperate changes the grout will come out,” he says.