Light Coverage

Get the skinny on how to install thin porcelain tiles
By Arthur Mintie
March 25, 2010

There is no question that for the “wet areas” of the home—the kitchen, bath and foyers—ceramic tile has been and will continue to be the surfacing material of choice. Durable, easy to clean and maintain, and available in a multitude of sizes, shapes, textures, designs and colors, it is one construction product offering that always seems to make sense. And when it’s professionally installed with state-of-the-art systems consisting of a fast-curing adhesive, waterproofing that protects the substrate and a high-performance, nonporous grout that comes in a full spectrum of non-fading colors, virtually any ceramic tile project will last for decades.

On top of that, many of today’s best tiles and installation systems contain antimicrobial components such as Microban. This means your fantastic, long-lasting installation helps to prevent mold, mildew and harmful bacteria strains. It all sounds too good to be true!

So what’s next? With all of this progress and upgrading, what could possibly be more beneficial for the kitchen and bath relative to ceramic tile installations? The answer is a product category that has received high marks in those countries around the world that consume a greater amount of ceramic tile per capita than we do in the United States: thin porcelain tiles.


What are these thin tiles, exactly? Most, which recently have been successfully introduced throughout Europe and the Middle East, are durable yet ultra-thin large-format, fully rectified porcelain tiles. Many measure less than 1/5 in. thick and still represent the perfect blend of technical finesse and design aesthetic. Some are offered in formats as large as 24 in. x 24 in., and all are lightweight and ideal for use both as indoor wall tile or in any kitchen or bath flooring project. Most notably, the cost of removing or demolishing existing floor coverings can be eliminated, since this unique category of tile can be directly installed over the previous floor or wall product.

But what about installation?


First, some history. More than 50 years ago, when tile was called for in the home, a thick mortar bed had to be used to ensure a strong installation. Housing construction had to be set up to accommodate this procedure. Translated, this meant rooms such as the “wet areas” had to be built with a recessed substrate. Over time, installation procedures changed, offering an alternative process to the thick mortar bed method. For the most part, since the adoption of those changes, most tile installations now utilize the “thinset method,” which, in very condensed wording, replaces the thick mortar bed with an efficient, thinner stratum of bonding material.

This process, which was invented by Dr. Henry M. Rothberg, founder and chairman emeritus of Laticrete International, Inc., revolutionized tile installation worldwide. For new construction, areas that were formerly designated for thick mortar beds and required being recessed to a lower level than surrounding substrates could now be on the same plane. The amount of weight on the substrate when the thinset method was put in place was much less than that when a thick mortar bed was used.

With today’s thinner tiles, the height from substrate to surface is shortened—thus minimizing the need for “shaving” door bottoms and “adjusting” thresholds—and in certain cases, if the correct installation system is used, thin tiles may be installed right over existing tile. To ease the challenges associated with installing these innovative porcelain tiles, the following installation systems can be specified.
thin tile installation SUBSTRATE PREPARATION

The main challenge for installers is to make sure that the substrate is extremely flat so as to achieve the required coverage on the back of the thin porcelain tiles. The goal is to attain at least 95 percent continuous adhesive mortar coverage (with no voids) for interior wet area and exterior applications, and at least 80 percent coverage for interior dry areas. Therefore, the flatter the substrate, the easier it will be to create the desired coverage for the large-format thin porcelain tiles. Self-leveling underlayments or polymer-fortified leveling mortars can be utilized to properly prepare the substrates. In addition, the inclusion of a thin load-bearing waterproofing membrane is also a good idea for wet area applications to protect adjacent spaces and areas below the tile installation.


Once the substrate is prepared, the thin porcelain tiles are typically installed with a high-performance polymer-fortified thinset mortar specially designed for large-format tiles. These adhesive mortar types include non-sag properties and help the installer to achieve the required coverage. Some tile types are supplied with a mesh/resin backing. Although the same high-performance polymer-fortified thinset mortar can be used for tiles with a mesh/resin backing, at times an epoxy adhesive may be better suited.

In all cases, maximum adhesive mortar coverage in accord with the appropriate ANSI requirements must be achieved in order to prevent the tiles from cracking. Care must also be taken when simply removing a tile to inspect the thinset mortar coverage during the installation process and while the mortar is still wet. The tiles can crack during this process.


Since the tiles are so thin, extra attention must be given to “clean out” any adhesive mortar left in the joints during the installation in order to facilitate grouting and the acceptance of enough grout within the grout joint. In most cases, half the depth of the grout joint should be available to receive the grout. For 1/8-in.-thick porcelain tile, that would be only 1/16 in. This may not be enough to allow the grout to remain in place. Therefore, the entire depth of the tile should be free of adhesive in the joints to receive the grout.

Joints scheduled to act as movement joints should also be cleaned out of all adhesive mortar and grout in order to receive a bond breaker tape and the suitable sealant so as to allow the movement joint to function correctly. Use a suitable flexible silicone sealant to treat the movement joints. Follow standard industry guidelines for movement joints in accord with the Tile Council of North America’s movement joint details and information EJ-171.


Because today’s thin tiles are half the weight of their more conventional counterparts, which generally measure roughly 1/2 in. in thickness, their use can result in a significant load-bearing reduction on any building structure. Thin tiles also make economic sense, as they save precious time and labor expense relative to removing the existing wall or floor surface prior to the actual installation.

—Arthur Mintie is director of technical services for Laticrete International, Inc., a family-owned business dedicated to innovative tile and stone installation systems. For more information on the company, visit www.laticrete.com.
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