Glass tile is hot. Page through shelter magazines from Dwell to House Beautiful , and you'll be mesmerized by sparkly, jewel-like glass tile installations in cutting-edge kitchens and baths. Ask any design-forward pool builder, and he'll tell you more clients are asking for glass tile than ever before.
In addition to its unquestionable design advantages — it's just plain beautiful — glass tile is a good choice for a pool or spa because it's durable and unaffected by water chemistry when properly installed. But it's not for everyone: Glass tile can be expensive, and any tile installation will add 14 to 21 days to a job schedule to allow for sufficient curing time.
Builders should work with a skilled and qualified tile contractor to do the tile installation, but the more the builder knows about the process, the smoother the project will go. Greg Andrews, a tile contractor in California, has become synonymous with extraordinary glass tile installations in pools. He took time from a busy speaking — and tile-setting — schedule to share his thoughts on the anatomy of a glass tile pool.
SHELL INSPECTION
The pool shell is the foundation of any project, and while controlling cracks, fittings, pipe location and the like are important in all pools, they are critical in an all-tile pool. An applied finish like plaster or pebble can tolerate more variance, but tile requires more precision. For this reason, Andrews starts every pool by inspecting the shell and bringing it up to standard where necessary.
"Cracks are one big thing I look for. In particular, the interface of the coping with the top of the bond beam," says Andrews. "There's movement there, and those movements will translate into cracks.
"At that interface where the coping meets the tile we always put a joint [that allows for movement and keeps tile and coping from cracking]. Movement is going to happen. If it's isolated from the tile, so the crack doesn't penetrate behind the tile, it's not a disaster."
Andrews also looks for other cracks or weaknesses in the shell. If the cracks aren't remedied to his satisfaction, he spells it out in the contract. "I just finished writing up a contract for a super-high-end pool that had failed; it was done about five years ago and tiles were falling off — they have to redo it," he says. "And that's one contingency clause that I put into my contract: The price is contingent on the inspection of the shell. The last thing we want to do is rip off the tile and then realize there's a huge fissure going across the pool."
Because the vessel and its surface need to be as precise as possible, Andrews next determines if there are any areas where he might need to move pipes. "If an inlet pipe or a return line or anything like that is in an odd place and needs to be moved, that's the time to do it, because you don't want to start the tile work and then realize you have to move the pipe and start jackhammering."
Andrews also inspects for areas of the shell that may be out of square or out of round, and he examines the lights to make sure they're square and in position.
SHELL PREPARATION
After the inspection, Andrews may have a list of problem areas to add to his usual preparation work, which includes chipping around all pipe penetrations and checking for voids or cavities; moving and/or straightening out pipes identified during inspection; straightening light rings if necessary; jackhammering any out-of-round or out-of-square surfaces and washing the entire surface in preparation for waterproofing.
"Most leaks occur around either a light or a pipe fitting," says Andrews. "There's always a little bit of settling or slump before the concrete sets up, and that generally occurs around fittings and in particular around lights, because there's a larger mass of concrete underneath, and when the concrete is wet it will slump a little and create a cavity."
"We always like to take a light chipping hammer and clean out around all of the fittings and pipes, and deal with voids in the shell right then and there." This extra work may not be cost effective with a plaster application, but it's well worth the extra time for a glass tile pool. "A plaster job may be $5,000, and if it leaks, they have to go back and deal with the leak, but it's not as disastrous as a $100,000 tile swimming pool. Once you have something tiled it's difficult to tell where a leak is coming from. We just have to be very careful," he says.
WATERPROOFING
While there may be legendary discussions over whose responsibility it is to waterproof the shell, Andrews takes it on himself to make sure he's working with a watertight shell.
"Contrary to popular belief, tile is not waterproof, so a waterproof coating needs to be applied to the shell prior to application of the mortar bed," he says. "In some cases, when a pool needs to be absolutely watertight, as if it were a shower pan or roman tub inside a residence, an elastomeric waterproof system can be used. This might be necessary if a pool is in such close proximity to a downstairs living quarters that there is a threat that moisture might migrate into the house, but in most cases, I would consider it an unnecessary overkill.
"I generally use a cementitious waterproofing material such as Thoroseal or Xypex. Thoroseal creates a waterproof barrier while Xypex actually grows crystals into the concrete to block water penetration. I've used both products successfully, however I feel that Xypex is more specifically designed for the waterproofing needs of a pool.
"Apply the waterproofing following the manufacturer's instructions. I always like to apply a scratch coat of mortar while applying the final coat of waterproofing in order to achieve a positive bond between the two products."
Andrews uses one part Portland cement to four parts washed plaster sand for the scratch coat, and advises leaving plenty of room around pipes for fittings that will be installed after the final coat of cement is complete.
FLOAT COAT
After the waterproofing and scratch coat, Andrews applies a mixture of one part Portland cement to four parts washed plaster sand as the float coat. "This is a very important phase of the installation, as any inconsistencies in the surface will show up at night when the pool lights are on," says Andrews. "While we're doing that step, we take a lot of time in measuring out dimensions so that when we do steps and seats and things of that nature, we don't end up cutting a bunch of tile. We try to do the cement work and .oat it out for full tiles. That way, once we do start laying tile, it falls right into place."
FITTINGS
"After we do our cement work, we set our fittings," says Andrews. "You never know exactly where the finished surface of the pool is going to be until all the cement work is done, because we do build out to particular dimensions.
"Once the finished surface is established, all of the pipe fittings can be installed. Just prior to installing the fittings is a good time to straighten any crooked pipes by heating and bending them into place if necessary. They can be cut and glued into place so that they flush out with the surface of the tile. Once they're installed, the cavity around them should be packed with hydrolic cement to ensure a watertight seal."
THROUGH THE LOOKING GLASS
Best practices dictate careful preparation of the pool shell for any surface, whether paint, plaster or porcelain tile. But with glass tile, there's one more reason to start with a perfect shell: Glass tile is often transparent.
"With a lot of the glass products these days, they serve as sort of a window looking into the substrate behind them," says Andrws.
"If there are inconsistencies in the substrate, that thinset can cure differently depending on the rate of suction, or if there's a heavy buildup in certain areas. In years past, as long as the tile didn't fall off the wall, we were fine with it. Nobody knows what goes on behind it and nobody really cares, quite frankly, because if the tile's not falling off, there's no issue! But now not only does the tile have to be well-bonded and wellset, but the substrate has to be very carefully prepared, because we're going to be looking at it."
Next month Andrews discusses installing the tile onto the prepared shell.
Worth The Wait
"As new setting materials and new techniques come along, sometimes the folks doing tiles in the pool industry may not be getting the information quite as quickly," says Scott Fleming of Oceanside Glass Tile. "That's why you see us at AQUA and other shows; we're truly interested in helping the pool industry learn more about what the tile industry has to offer."
Fleming notes that time is one significant requirement that builders must factor into the job. "What hurts all tile installations, including glass tile installations, is using the wrong setting materials and not curing them a long enough period of time. Most of the thinset manufacturers recommend a minimum of 14 to 21 days cure time prior to submersion in water. It is very unusual for a pool contractor to wait that long to submerse a pool, but that requirement is written on the bag of most thinsets that are recommended for installing glass tile and other tiles in pools."
