Today more than ever, the world’s ceramic tile community rightly insists that its products be considered as an installed system. They fully recognize that tile doesn’t serve its purpose or demonstrate its capabilities until it’s not only properly manufactured but installed. This is also where the Ceramic Tile Education Foundation dedicates most of its efforts. It should also be extremely important to retailers or contractors who do business in tile to fully grasp the technical basis for a successful job, and to understand the critical properties of ceramic tile and the environment in which the tile will be installed.
There are several types of ceramic tiles. Broadly speaking, ceramic tile is made when non-metallic and inorganic materials are heated to a temperature high enough to cause particle fusion. Specifically, tile is surfacing product with a thin cross section, made of clays, quartzes, talcs, feldspar and other earthen products which are shaped and heated until fusion occurs. Marble and other types of products are often referred to as “tile” but in reality they only share the modular nature of tile. A successful stone installation is far more demanding than a job involving ceramic products. For now, let’s focus on ceramic tile products.
Sometimes it appears to be a well-kept secret, but let me start by assuring you there are performance standards for ceramic tile products. The properties of tile are spelled out in American National Standard Specification for Ceramic Tile (ANSI A 137.1). This publication has recently been updated to reflect the latest in manufacturing innovations as well as the availability of new tests for performance properties. The many revisions include a reduction in allowable size variation, a new classification system for tile, and for the first time ever, a shading guideline for field tile. This long-awaited document is currently out for review and will likely be balloted this year. There is also an International Standards Organization (ISO) standard 10545-1 to 17. The majority of U.S. test methods use the same ISO methods with minimal variations. In the U.S., tile is tested using what is known as the American Standards for Test Methods (ASTM). Test labs currently use 16 tests to determine tile type and whether they meet specifications.
The Tile Council of North America has a lab for its own ceramic tile tests. It also helps manufacturers and purchasers determine if the products they make or use meet the required specifications. What does all this mean to distributors and retailers? The tests offer independent verification of performance standards. Without them there can be no expectation of performance beyond those represented by the manufacturer. Buyer beware. Keep your customer happy, use tile that meets basic performance standards.
I would need a book-actually a very large set of books-to detail all the nuances of a top quality tile installation. So let’s just focus on a few hot button items anyone selling tiles needs to know. The most popular products these days seem to revolve around glass and large tile, especially rectangles. Glass tile is very tricky to install. What works with one manufacturer’s product does not work with another’s. Many tile installers wrongly assume it is “just like tile.” Not quite. It is modular, and you do bond it but from there the cautions abound. Glass has very little if any porosity to it so it lacks the capillary structure needed for cement to bond. What’s needed is a premium latex or polymer modified product. Some glass favors one product over another due to properties of the glass and the thinset. To safely install glass, use only the specific recommendation from the manufacturer of the product you are installing. Most manufacturers will tell you not to use a membrane; others strongly recommend it.
One definite requirement is time. From my experience, impervious products-those with no absorption-installed over other impervious products will require a very long drying time prior to grouting or even foot traffic. If using a cementious grout, a rule of thumb is one day per square inch for grouting, using the correct thinset, and two days for traffic. Using an epoxy grout on glass is a bad idea in my opinion. (And the calls and e-mails I receive from readers back me up.) Epoxy will not allow the setting material to reach final cure, typically 14 to 28 days. Nor will it allow for movement, because the strength is too great. There are many additional cautions, but these are the areas that seem to be most widely misunderstood.
Large tile used to mean anything over an 8”by 8”. Now I’m not sure what it means. We ‘re seeing 2’ by 2’ and even 2’ by 4’ on the market, and with advances in technology they’ll get even bigger. Bonding, of course is going to be a major concern with tiles that big and so is lippage, the condition where one tile is higher than the other. Let’s start with bonding. Current concrete specifications and practices do not allow for satisfactory installation of tile much bigger than a 12”by 12”. Also, wood construction does not fall in the category of “super flat,” the type of finish profile that allows for lippage free installations. These two points come into play when you are determining what installation method to use. Unless you have a super flat floor you won’t be able to use a standard thinset. It will not do the job for several reasons. One, above 3/8” to a 1/2” in thickness, this type of thinset has very little bond strength.
To put it in perspective, this is why they don’t build roads out of brick mortar. If the undulation of the floor is minimal, you may be able to use a medium bed mortar which is designed to be applied from 5/8” to 3/4” thickness. That may be fine but the customer needs to be made aware that this will result in a higher installation cost. Not only does the product cost more, but you will need twice the thickness of a conventional thinset mortar. It is not at all unusual to come across a floor where even that amount will not allow for a flat floor. This is where trouble begins. The tile must be fully supported with a minimum of 80% coverage equally distributed. This can be quite challenging when troweling out a floor.
Many installers use a popular method called “5 spotting,” where a dab is placed at each corner and the center of the tile. This makes it much easier to level the tile as there is minimum contact with the tile itself. But that too can lead to problems. Ceramic tile, a thin clay surfacing unit, is NOT a structural panel. It needs support equally distributed to support any type of weight or absorb any type of normal building movement. If you do a “5 Spot,” moisture (even high vapor emission in the slab) will eventually collect in the voids under the tile. This can manifest itself as either latex leaching (the re-emulsification of polymers) or effloresce, the diffusion of a naturally occurring salt in all cement products. If you have some white spots here and there, it is either one or the other.
That is just some of the considerations involved in tile selection. As beautiful and versatile as it is, from a product perspective, ceramic tile is as complex as any flooring material. Also, given the endless array of variables, ceramic tile installation is perhaps the most challenging. And that’s just the floor. If you add tubs and showers, that is unequivocally a true statement. Expert installation requires a substantial knowledge of building construction and installation methods. If you are fortunate enough to have found someone with these qualifications, I advise you to treat him or her as a very valuable commodity.