Around the pool perimeter we're laying 30mm ivory travertine stone and continuing it onto the pool deck. The 30mm thickness provides a nice lip for the pool edge. The two main edging options for the lip are square edge or bullnose (i.e. rounded). Our stone tiles already have a square edge (bullnose edging typically costs more) and we'll be keeping it.
Pretty much every tile needs to be cut to size
The coping overhangs the pool by around 25mm and also overhangs the stackstone-clad walls slightly. The width also varies around the perimeter given different features (garden bed, deck etc) on each side.
The 30mm stone comes in a few different sizes all the way up to 600x600mm, with price (per area) increasing with size. ~600mm is a good length for the coping so we are using 610x405mm pieces, laid lengthways and cut to the appropriate width. The figure above shows the plan. To minimize cuts - which are a huge pain - I'm using the full tile on the deck side of the pool, as it will only marginally overhang the edge of the pool beam and the pool deck in continuing there anyway.
The cutting process involves using our table saw to slice of the excess and then polishing (and beveling) the cut edge to match the honed finish on the original edges. Since the guides on the table saw are terrible (for $200 I'm lucky it cuts at all ;-) I used my construction laser to more easily line up the tiles. Unfortunately the saw only cuts a maximum length of around 580mm and so the process involved cutting halfway, stopping the saw, sliding the tile back around 50mm, and then completing the cut.
The corners require a larger tile to allow for a reasonable radius for the rounded inside edge. These are 600x600mm tiles and weigh around 30kg each. To create a nice rounded corner, I bought this unwieldly, 150mm diamond hole saw bit:
With the combination of this, the tile saw, an angle grinder, some sandpaper, and a very steady grip, I was able to create a pretty decent corner in the large tiles:
Mildly alkaline, chlorinated, salt water is not ideal for travertine
Travertine is a soft, highly porous stone. In the absence of any protection, the pool water will cause significant damage to it over time. To protect it and ensure longevity, we will be both consolidating and sealing it.
Whereas a sealer simply tries to avoid the ingress of water into the stone, a consolidator also strengthens the stone from within, reducing friability (fancy word for crumbling under pressure) and softness.
For the coping tiles that are immediately adjacent to the pool water and thus most at risk, we are pre-treating with Dry-treat 40SK. If one believes the marketing, the 40SK offers:
- Penetrating, permanent water repellency plus consolidation of softer materials, for premium protection against problems caused by water and water borne salts, including: efflorescence, salt spalling, freeze-thaw spalling and picture framing
- Popular for sealing sandstone, limestone, travertine, concrete dry-stamped pavers and composite stone pavers around salt water swimming pools
- Retains natural surface color and finish
- Keeps surfaces looking new for longer, makes cleaning easier, and dries quickly even after heavy rain
- Breathable: water vapor escapes freely, avoiding moisture build-up inside the material
Treating the stone prior to laying it allows for it to be almost immersed in the product, increasing penetration and ensuring a good application.
Once the stone is laid and grouted, we'll seal again with an impregnating Silane/Siloxane based sealer designed for chlorine and salt water pool environments. We'll also usre that on the pool deck.
Adhering to multiple substrates
The concrete bond beam we poured around the top of the pool is level with the top of the fiberglass shell. The coping tiles will sit atop this beam, straddling the concrete on the outside and the fiberglass on the inside. This presents a potential problem, as different substrates have different adhesion properties, different thermal expansion coefficients etc.
Since we are already using SMP Evo on the wall tiles, we'll also use it for the concrete portion of the coping. For the fiberglass to coping stone, we're using Sikaflex 11fc. I've become a bit of a fan of Sika products during this build, and the 11fc promises to perform well for this task. It's a polyurethane based adhesive that remains permanently flexible, which is important given the potential for differential movement between the concrete and fiberglass substrates.
I got some unwelcome insight as to just how strong and flexible the 11fc is, as I decided to recut a tile I had already glue down around 20 hours prior. The tiling cement was not fully cured and was relative easy to dislodge. The 11fc on other hand, was well and truly stuck. Flexible, but not budging.
In the end it took over an hour with a hacksaw blade between the tile and beam to get it free.
The (almost) finished product
We still need to grout the gaps, and the inside fiberglass/stone join needs to be sealed against water ingress with some Sikasil Pool silicone sealant, but it's looking good so far!