Ceramic tile and natural stone remain important cornerstones of the flooring installation industry, with new methods and installation materials constantly being released to keep pace with product advances including longer and thinner formats. Manufacturers of installation materials for the segment weighed in to talk about new trends, common mistakes when installing the product and what to watch for when branching out into more specialized installations.

Trends in the market. Mark Pennine, Ardex Americas tile and stone specialist, said one trend he sees is “the development of lightweight, highly-modified thin set mortars designed to improve adhesion, extend working time and offer improved non-sag properties.”

However, to get the best performance out of these products, manufacturer instructions need to be followed. “Each product must be mixed and applied in a certain way to achieve optimal performance. Overwatering cement-based products results in a weaker finished product and heightens the risk of surface efflorescence.”

Mike Boenisch, Bonsal American/ProSpec technical services manager, said panels as large as 3’ x 9’ and thin tiles ranging from 3 to 6 mm are becoming popular, requiring more specialized installation. “The unique size and thinness requires special installation methods and materials. I would estimate that you will begin to see new ANSI standards to cover large, thin tiles in the near future.”

No matter what product is being installed, he follows one rule of thumb. “It is important to choose the correct adhesive or mortar for the tile type, substrate conditions and environment based on performance criteria and not just price.”

Steve Taylor, Custom Building Products director of architecture and technical marketing, said the advances in the segment include “products that are easier to use, require less prep work, contain fewer components and are easier to mix and spread. Grouts have better color consistency throughout the assembly and are more stain-resistant. More mortars are suitable for both thin set and medium bed applications.”

He said the most common mistake he sees with installers and contractors choosing a product is “using a thin set mortar for large tiles greater than 15”, when a medium bed mortar should be used. Dense tiles require higher polymer-modified mortars and we find the installer using the lowest-cost and least-modified mortar. These types of errors will lead to bond failures in the future.”

According to Tom Domenici, H.B. Fuller Construction Products area technical manager, a recent development in tile-setting products is “the improvement of premixed polymer resin grout. While there is currently no product or installation standard for this type of grout, it provides an excellent alternative to the cementitious grout that requires mixing with water or an admix.”

Arthur Mintie, Laticrete senior director of technical services, said the rise of reduced thickness porcelain tiles has led to the need for technologically advanced setting materials. “It requires high-performance adhesives to provide not only the proper bond strength, but sufficient ‘build’/non-slumping performance to prevent tile lippage. In addition, tile adhesive manufacturers need to ensure the tile adhesives are compatible with the multitude of backing materials used today as reinforcement on the back of large-format or reduced thickness tile.”

He also stressed the importance of training. “It is imperative that contractors take the time to effectively train their employees on the use of the new technologically advanced products that continue to be released into the marketplace.”

According to Dan Marvin, director of MAPEI technical services, the products used today are simply not the same as the ones used many years ago. “The days when a 1/2” thick tile or stone bore the brunt of the loads on the floor is rapidly dwindling. Thin tile panels are pushing the limits of tile installation products. Tiles 3’ x 10’ or even larger require products that are flexible, don’t slump and provide superior support when set. When an individual tile covers 30 feet without a grout joint, the mortars and grouts used must be highly modified.”

He added that contractors and installers need to pay special attention to movement joints, no matter whether the installation uses tile or stone. “Allowing for expansion is a must. Most of the bonding failures we see are due to the tile (and especially glass tile which expands more) expanding and contracting at a different rate than the substrate on which it is applied. The Tile Council of North America (TCNA) publishes guidelines for movement joints in tile and stone installation to help installers and architects plan for this movement.”

Michael Venturelli, Q.E.P. vice president of sales, said, “The increase in various types of natural stone and the new thin tile has seen an increase in new mortars and grouts such as high-strength adhesives and one-component grouts.”

He added, “Coverage is the single most common error and cause of failure. This is typically due to worn out trowels and application tools. Q.E.P. continually promotes information to contractors and installers to be sure they check the gauge on the trowels and the condition of grout floats.”

Alan Kin, Texrite sales/technical, sees advancements in grout for better color retention and resistance to color shading as well as the move toward medium bed tile-setting mortars for large format tiles. The biggest mistake he still sees installers and contractors make is “installing over contaminated bond surfaces. An easy test is to put droplets of clean water on the concrete/slab surface, which should readily absorb or soak into the surface to show a clean bond is ready for installation.”

Dealing with efflorescence. To remove efflorescence, which can appear as a white, chalky powder on the surface of a grout joint, “use a nylon brush, wet or dry, to scrub the surface of the grout joint and remove the salt residue. If efflorescence has already occurred, use a grout cleaner specifically manufactured [for the task]. Severe cases may require the use of phosphoric acid or sulfamic acid crystals,” Pennine said.

Boenisch offered these tips: “Check the substrate for moisture coming up to the surface and if present correct before installing the tile. Use factory-prepared grouts following the manufacturer’s recommendation for water amount. Before cleaning, allow the cement grout to cure until there is no transfer of grout when lightly touched. When cleaning the grout, use as little water as possible, being sure not to leave any water pooled in the joint.”

Taylor said, “The best way to remove efflorescence is with a mild acid.  However, some stone tiles are sensitive to acids and in this case one should use a mild, non-acidic abrasive cleaner. In all cases one should check with the manufacturer for the best procedure and test in an inconspicuous location.”

According to Domenici, “Preventing efflorescence is often easier than removing it. Some high-performance, polymer-modified grouts have been specifically formulated to prevent efflorescence and provide color consistency. Consult with your manufacturer to learn more about these options.”

Added Mintie, “If efflorescence manifests itself, typically a light phosphoric or sulfamic acid wash with a scrub pad or brush can be used to remove it.”

Marvin recommends choosing a non Portland-cement-based grout to eliminate efflorescence concerns. “The difference in cost per square foot is pennies but the advantage in not having to figure out how to clean or replace the grout is enormous.”

Venturelli noted, “The single most important key to stopping efflorescence is preventing moisture from traveling up through the substrate with a cleavage membrane.”

Kin said efflorescence can appear in three ways. One is the look of frost or haze. “This is more just a nuisance.” The second is the type that cleans off but shortly returns. “This is due to a water vapor source being drawn to the surface.” The final is a heavy occurrence resembling spilled paint or an “oozing and heavy white flow, due to an improper barrier or an improper material in the structure or adjacent to the structure.” He said while there are products out there to help with efflorescence, the best treatment is prevention. “Minor efflorescence cases could be avoided by letting the mortar setting bed cure for 24-48-plus hours before grouting. Use of fast-setting mortar products and faster hydration grouts can counter the extended wait time.”

Specialized installation conditions. Specialized installations such as those completed outdoors, using glass or metal tile, or requiring natural stone may present different challenges than the typical ceramic tile installation. “Anytime an installer is faced with an unfamiliar tile installation or an installation they may have never done before, they should always contact the tile manufacturer for proper installation procedures and setting material recommendations. The TCNA Handbook is a wealth of information for installation procedures,” Pennine noted.

Always be sure to understand the technical requirements of the product, Boenisch said. “Coverage of the tile mortar is critical. Exterior applications require 95 percent or greater coverage while interior is a minimum of 80 percent. For large tile, be sure to have all edges and corners supported with mortar to prevent cracking. Glass tile, typically being translucent, requires 100 percent coverage and a white polymer-modified thin set mortar. Metal tiles may require an epoxy adhesive or modified mortar. Underwater applications, which typically use a porcelain tile, should use a polymer-modified mortar with 95 percent or greater coverage.”

Stone can be extremely sensitive to moisture, Taylor stated. “Some stone will curl or warp when exposed to the moisture in standard thin set mortars. All stone should be tested by a qualified lab, and if it is found to be sensitive to moisture it is best to install it with a 100% epoxy mortar. In some cases a rapid-setting mortar can be used, but the manufacturer should be consulted before starting the project.”

Domenici stressed the importance of achieving proper mortar coverage – up to 95 percent for exterior, shower and wet-area installations, and 100 percent coverage for natural stone. “For natural stone and large-format tile, back-buttering will help ensure 95 to 100 percent coverage.”

He also shared some tips for outdoor installations. He recommends tenting the area to protect the installation from direct sunlight. In cold temperatures “leaving bags of mortar outside will extend their cure times. If doing so is unavoidable, be sure to keep these extended cure times in mind during and after installation.” He added, “Choose a polymer-modified grout that has lower water absorption for outdoor installation. Sealants and caulks can prevent external moisture from penetrating your installation, further protecting it from the elements.”

When it doubt, consult industry resources such as the TCNA Handbook, Mintie said. “A contractor should work with their tile and stone installation manufacturer to ensure that the appropriate installation materials are selected for the specific application. It’s important to note that tile and stone finishes can behave very differently when installed in a specific application. In addition, not all installation products are suitable for every application.”

When working with tile or stone outside, “take into account freeze-thaw and heat soak when selecting installation products,” Marvin noted. “Select an ANSI A118.15 mortar for exterior and elevated installations and make sure the mortar meets all of the requirements of the standard.” Additionally, when working with glass tile, “use a white mortar and flatten trowel ridges to maximize the likelihood of success.” As for underwater applications, “these require mortars that set up quickly, can expand somewhat with temperature swings and won’t degrade in bond over time due to chemicals.”

Venturelli stated, “All [of these specialized installations] require special consideration on adhesives and grouts, such as polymer-modified adhesives and non-sanded grout for glass and metal tiles.”

For natural stone, “white Portland cement-based dry-set mortars are recommended unless the use of 100 percent solids epoxy mortar is specified by the stone manufacturer,” Kin noted. As for glass tile, “approved glass tiles meet different indoor/outdoor exposure levels as compared to their ceramic or porcelain counterparts. The establishment of ANSI A137.2 was created for this very reason.”

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Kin also shared his perspective on working with metal tiles. “All metal tiles are not the same; some metal tiles require epoxy or silicone adhesion and other alloys/metals are not designed for Portland cement-based setting mortars. There are also many metal alloy compositions that could vary in color or finish and not be generally applied with a single method or adhesive. Unless some history or testing of the metal tiles are known, it would be a best practice method to proceed with care and conduct a pretest.  An experience installer bids extra tile sheets/materials to perform test cutting, test bonding and test grouting of metal tiles.”