Case #465, titled “Dealers Choice” has a Mr. Jacques Chardonnay, aka “Black Jack”, due to his propensity to lay down a few bucks at the gaming table, unsure as to where to place his next bet. At stake is the future of his ceramic kitchen floor.
Black Jack very much likes his ceramic floor, but with six to seven cracked tiles in need of replacement, the question is, does he roll the dice, and surgically remove and replace each cracked tile individually? Or, with a five-pound sledge, cover all his bets, pound the hell out of the floor, then replace the entire surface?
Jacques, a gambler, and with several spare ceramic tiles in the basement (because a good gambler always hedges his bet) he’s leaning towards the strategy of replacing the six to seven tiles, since it would would be far less intrusive to the general workings of the household, rather than having to destroy and replace about 200 pieces.
The gamble of course, or risk factor in replacing only the cracked tiles, lies in the fact his kitchen floor may inherently be compromised. In other words, if the integrity of the floor’s joist system falters as guests linger around the center island, thereby allowing for a little bounce, or the plywood used as the underlay was too thin, these newly cemented tiles may crack as easily as their predecessors. After all the effort that would be required to carefully remove, reinstall, and grout even a small number of tiles, it would be heartbreaking to watch them crack all over again.
Decision? We’re replacing only the cracked tiles. Are we carelessly throwing caution to the wind, tempting fate, or playing a game where the odds overwhelmingly favor the house? Perhaps. However, before setting these new replacement tiles in position, we’re going to tilt the odds a little more in our favor, load the dice, or mark the cards, so to speak, in order to lessen our risk of going bust.
The reason for tile failure is most likely related to the floor moving, as opposed to these tiles being simply defective. Once the cracked tiles have been removed, and before we simply mortar the new tiles in position, we’re going to re-strengthen the bond between the 5/8” plywood floor, and what’s in this case, a half-inch plywood underlay. Once standard issue, spruce plywood is no longer the preferred choice as an underlay. Plywood is strong, but it always remains somewhat flexible, which is great in most cases of general household construction, except for the case of ceramic tiled floors, which need an underlay to be inflexible and rock solid.
With some of the cracked tiles sporadically spaced amongst the good tiles, and others creating only a small cluster of cracked tiles, it’ impossible in this case to replace the underlay. With the cracked tiles removed, make sure to completely remove the old mortar and grouting from the space. Because any mortar or grout residue left behind will either lessen the strength of the bond between ceramic and plywood, or interfere with how the replacement tiles lay in position, really cleaning out the space is key. Use a Shop-Vac and water dampened cloth to ensure every bit of dust is removed from the plywood underlay. Next, use 1-1/2 inch laminating screws, screwed every four inches apart, to effectively bond this weak spot in the underlay to the plywood subfloor.
Don’t use regular wood or floor screws. Floor screws work well to fasten plywood to spruce lumber, relying on their length for strength. Laminating screws have a heavier thread that runs the entire length of the shaft, and are more effective at bonding two sheets of plywood together. With this weakened area now a lot more solid, the tiling can begin. Then, we wait and see how the cards fall.
Case #465 closed. Good building.