Tech Talk – October 2014


Tiling commercial kitchens

tom_plaskota_webBy Tom Plaskota, Technical Support Manager, H.B. Fuller Construction Products

In a typical commercial kitchen, chefs stay on their feet for hours as they hurry from station to station, waiters race to get food out to eager patrons and, inevitably, hot food, drinks and raw ingredients slosh onto the floor – all in a space that must be sanitized frequently to ensure the safety of both employees and customers. Tile installations in commercial kitchens must hold up to these unique demands, because a temporary closure of a restaurant can be costly. Carefully considered product selection and installation strategies will help you create safe, long-lasting and beautiful commercial kitchens.

1-TT-1014Tile selection

For commercial kitchens, look for unglazed tile rated for extra heavy or heavy use. Durable tile with nonslip characteristics will help keep fast-moving restaurant employees on their feet. The tile should also have low porosity and chemical resistance, since these areas will be frequently exposed to moisture and cleaning agents. Select tile that has been tested according to ISO standard 10545-13, which evaluates resistance to chemical interaction. Quarry tile often meets the requirements of commercial kitchen environments.

Substrate preparation

Subfloor requirements for commercial kitchens vary by state. Some states dictate the installation of floor drains, and require that the floor slope toward the drain, going so far as to specify the exact degree of slope. You should familiarize yourself with your state’s codes, and the general contractor or specifier on each commercial kitchen job should clearly communicate whether achieving the required slope is the job of the concrete contractor or the tile installer. If the concrete contractor is responsible for sloping the subfloor, check that they have correctly done so before beginning tile installation.

2-TT-1014If creating the proper slope is your job, use a mortar bed up to 2” in thickness to facilitate accurate slopes or planes, as per the TCNA Handbook. In wet areas, the use of a mortar additive in the mortar bed is recommended. Be sure to create the mortar bed before the application of a waterproofing membrane. The NTCA Reference Manual notes that, “If the proper slope to drains is not already established in the substrate, it should be established prior to the application of the membrane. Failure to slope the membrane results in moisture or water collecting in the mud bed or setting material.”

Following this recommendation is often essential, because many commercial kitchen installations require waterproofing crack-isolation membranes. These membranes protect the substrate from the repeated moisture exposure that occurs in commercial kitchens and help prevent the growth of mold and mildew. They also prevent in-plane cracks in the subfloor from telegraphing through to tile. In commercial kitchen environments, a cracked tile – beyond being a tripping hazard – can foster the growth of bacteria. For these reasons, waterproofing crack-isolation membranes are recommended.

Setting material selection

3-TT-1014Tile can be bonded directly to some waterproofing membranes, including TEC® Hydraflex™ Waterproofing Crack Isolation Membrane. However, for any installation, you must confirm that your mortar and membrane are compatible. Also, ensure that you select a mortar that will hold up to the unique demands of the commercial kitchen environment.

Very busy commercial kitchens – such as those in fast food restaurants – are often exposed to harsh cleaning agents. For these spaces, an epoxy mortar might be the best choice. Epoxy mortars offer high chemical resistance and are also extremely durable and impact resistant.

For all commercial kitchen installations, bond and durability are critical factors. Specific recommended mortars will vary for tile size and type, but for all tile, bond strength is essential. In kitchens, disbonded tiles can be both costly and dangerous. With this in mind, look for a premium polymer-modified mortar specifically formulated for your tile. For example, if the design requires large-format tile, opt for a premium mortar with non-slump and non-slip characteristics to meet the requirements of both the tile and the installation environment.

4-TT-1014The grout must also hold up to heavy commercial use and frequent cleaning. Look for a grout with superior performance – like TEC® AccuColor EFX® Epoxy Special Effects Grout. TEC® AccuColor EFX® was tested for use in food service environments and found to be resistant to food soils and compatible with enzymatic cleaners. Enzymatic cleaners are often used to break down food soils and accumulated grease, and no loss of grout occurred when TEC® AccuColor EFX® was exposed to these products. Its high-temperature formula is approved for surfaces subject to extreme heat or steam cleaning (up to 350°F or 177°C).

A properly-installed commercial kitchen installation, created with thoughtfully-selected products, will continue to be a safe, productive environment. Your understanding of the unique requirements of these spaces will help keep restaurant employees and patrons alike healthy and happy.

For more information about TEC® visit

The TEC® brand is offered by H.B. Fuller Construction Products Inc. – a leading provider of technologically advanced construction materials and solutions to the commercial, industrial and residential construction industry. Headquartered in Aurora, Illinois, the company’s recognized and trusted brands – TEC®, CHAPCO®, Grout Boost®, Foster®, AIM™ and others – are available through an extensive network of distributors and dealers, as well as home improvement retailers. For more information, visit

TEC®, Hydraflex™ and AccuColor EFX® are trademarks of H.B. Fuller Construction Products Inc. 

Tech Talk – September 2014

TEC-sponsorTile not manufactured to industry standards

In the upcoming NTCA Reference Manual, 2014/2015 edition, there is a revised section on the use of tile that is not manufactured to industry standards (p. 128 in the new NTCA Reference Manual; page 124 in the 2013/2014 NTCA Reference Manual if you have a current one on hand.)

This section is pertinent for a range of tile, especially large thin porcelain tile such as Laminam by Crossville®, Plane by StonePeak Ceramics, SlimLite™ by Daltile and the upcoming Thinner by Florida Tile, among others, discussed in the last two TileLetter issues.

The “tile contractor precautions” section is followed in the NTCA Reference Manual, by two letters – one that alerts the architect or general contractor about precautions concerning using tile that does not yet conform to ANSI Standards; the second is a sample letter the contractor can customize to the customer, A&D professional, or distributor that provides some cautions specifically about the use of thin porcelain tile.

For more information about the NTCA Reference Manual, visit online.

1-TT-0914Manufacturers’ standards

American National Standard Specification For Ceramic Tile A137.1 is the only nationally recognized specification for ceramic tile.

Many domestic and foreign manufacturers of tile produce tile products made to the “manufacturer’s own standards.”

In many cases, these standards allow variation in shade, density, consistency of texture, wear resistance, absorption, fractures, squareness, size, thickness, warpage, and mounting that are considerably less stringent than ANSI standards.

Some manufacturers make broad disclaimers in their literature, virtually relieving themselves of responsibility for owner dissatisfaction or for the performance and appearance of their products.

Some disclaimers deny responsibility after the tile is installed. Often, visual inspection prior to installation does not reveal inadequacies of the tile’s performance or possible installation problems.


New to the tile marketplace are families of “thin” porcelain tile products ranging from 3 mm to 7 mm in thickness. Consumer and installer familiarity with thin tiles is increasing in Europe, and such products have already entered the U.S. market. Thin tiles offer new design, environmental, and business opportunities for tile installers, but performance characteristics and installation requirements are different from those of traditional ceramic tiles, especially in flooring applications.

In general, there are four categories of tiles being promoted as “thin” – traditional dust pressed tiles (5-7 mm thick), tiles formed using a “lamina” process (3 mm thick), lamina products reinforced with backing materials, typically with fiberglass (3.5 – 4 mm thick), and lamina tiles sandwiched with fiberglass (6.5 – 7 mm thick).

The first category of thin tiles, which closely resemble traditional ceramic tiles (only thinner), behave similarly to traditional tiles, but are lighter. For flooring applications, they should conform to ANSI A137.1 pressed floor and porcelain tile requirements. They should exceed 250 lbf breaking strength unless otherwise guaranteed by the manufacturer for flooring applications. For wall applications, they should exceed 125 lbf breaking strength, unless otherwise guaranteed.

The second category of thin tiles (non-reinforced lamina tiles) is recommended by manufacturers for wall applications only.

The third and fourth categories of thin tiles (reinforced lamina tiles) have innovative mechanical properties, including impact resistance and deflection capabilities, and manufacturers guarantee such products can be used in both floor and wall applications. However, their inherent thinness, tendency to be large (sometimes up to 3 square meters), and ability to bend require different installation methods and handling. While different from regular tile installation methods, our members should have no difficulty mastering them. Manufacturers usually have thorough guidelines for installation, which should be closely followed.

Until such products are defined by standards, and consistent installation specifications for thin tile are developed, we urge our members and the industry at large to request installation and performance criteria from manufacturers and follow their instructions explicitly for suitable application.

Tile contractor precautions

The tile contractor should carefully review the manufacturer’s warranties and disclaimers to determine the extent of his risk and to take steps to avoid assuming the manufacturer’s and the architect’s responsibilities.

First, the tile contractor should clearly state the manufacturer’s responsibility in the tile contractor’s purchase order to the supplier.

Second, advise the architect or owner, in writing, that the tile he has selected is not manufactured to ANSI Standard Specifications and point out how the manufacturer has been relieved of responsibility by disclaimers and warranty limitations.

Tech Talk – Large thin porcelain tile update, part 2 – August 2014

TEC-sponsorLarge thin porcelain tile update, part 2

Manufacturers share wisdom about successful LTPT installation; contractors counsel caution

By Lesley Goddin

Last month, we looked at the burgeoning new category of large format thin porcelain tile (LTPT) from the contractor’s perspective. This month, we get the low-down from manufacturers of the products themselves – and tips on how to ensure a successful installation, with some words of caution with several more contractors who have had first-hand experience installing the materials.

Training – and experience with the product – cannot be emphasized enough! As an introduction to the product, NTCA has been offering training on LTPT all year at its Tile & Stone Workshop Programs, presented by Gerald Sloan and Michael Whistler at host sites around the country. Sloan and Whistler have attended trainings at various suppliers and setting material manufacturers to get up to speed on what these parties are advising for successful LTPT installation.

1-TechTalk-0814Training reduces fear factor

Crossville, Inc. has been very big on the scene with its Italian-made Laminam by Crossville LTPT – and has been at the forefront of conducting trainings for contractors to familiarize them with the products and the best way to work with them.

“It is not a big learning curve – the material is easy to work with –but without proper tools and training on the job, learning could be not so fun and maybe even expensive,” said Noah Chitty, director of technical services for Crossville.

StonePeak Ceramics, who manufactures Plane 5’ x 10’ LTPT in 6mm thickness, has been conducting twice-monthly, packed-to-the-limit classes at its Tennessee facilities to train installers on using the material. And it also sends a team to distributor locations and invites installers in to witness a live installation for a showroom vignette.

2-TechTalk-0814Todd Ward, vice president of national accounts and director of StonePeak Ceramics’ Plane program says, “Don’t over think it. We are still dealing with porcelain tile – it’s just a bigger size.” Ward points out that 25 years ago, the typical tile size was 8” x 8”, and then it grew to be 12” x 12”, 24” x 24” and larger. With training and familiarity with the product and the new installation methods required for the larger tiles, installers became proficient at working with this new material, he said.

These training opportunities are important, said Ben Szell of European Tile Masters (ETM), a company that has pioneered a number of different tools and pieces of equipment to simplify working with LTPT. They “equip the contractor to stage and choreograph the jobsite before the material are transported to minimize breakage, loss of time, and frustration.”

3-TechTalk-0814Daltile, which supplies fiberglass-backed 1m x 3 m 3.5mm SlimLite™ tile for wall use, has developed a CEU unit for the A&D community that “we are trying to coordinate with our architectural reps, to increase knowledge level and exposure,” said Gregg Link, product director for glazed wall/ceramic mosaics. And Daltile holds clinics at its local Sales Service Centers near projects where SlimLite will be used, to educate the installing contractor on information about the material, including handling, back buttering, and hanging it, so they go into the job feeling confident.

Crossville’s Chitty said that obtaining training can be a real feather in the contractor’s cap, offering “a way to be able to do something their competition can’t.” He recommends selling the tile simply as “large porcelain tile” to the end user, but with the caveat that it “requires qualified labor and specialized equipment if used in full sizes.”

4-TechTalk-0814And confidence is important, because several suppliers have seen skittish contractors overbidding jobs rather than rejecting them – “maybe 200% – 300% more than what a realistic labor rate would be – up to $25/sq. ft. to install,” Link said. “Which is really the same as saying ‘I don’t want to do it.’”

Chitty said that out-of-the-ballpark bids “aren’t good for anyone,” – it’s best to just step away gracefully or send the client to the supplier so they can help.

The right tools make or break the job

ETM’s Szell called LTPT “user-friendly,” since the virtual lack of tension in the product allows contractors to cut and drill very close to the edge. Tools that are specifically designed for this material are essential, Szell said, starting with proper transportation, and suction cup-based equipment to remove LTPT from crates and A-frame racks, cutters, tables and lippage-control systems, as well as trowels designed for full thinset coverage and an edge-finishing machine for beveling, mitering and bullnosing.

Adequate staff is key when handling the tiles, said Jim Whitfield, product manager for Florida Tile. The company will supply fiberglass-reinforced Thinner 1m x 1 m and 1m x 3m tile in 3plus (3.5mm) and 5.5mm thicknesses in 2015.

“The size of these large thin tiles requires at least two people to properly handle the tile from the container to the table for back buttering and also to the installation,” Whitfield said.” This is best accomplished by an aluminum frame with suction cup mounted on it to grab the finished side of the tile.”

And Daltile’s Lynn Mantha, product manager, glazed wall tile, suggested setting up a staging area with a large table ahead of time to handle the material. “You need a stable table for cuts and back buttering,” she said.

5-TechTalk-0814Though LTPTs are usually too large for typical jobsite wet saws, they can be cut by a good straight edge and glass cutter, Whitfield said. “There are also scoring tools on rails that can be mounted right on the face of the tile, making a cut precise and allowing for continuous pressure of the scoring wheel.”

Follow directions!

Florida Tile’s Whitfield emphasized that contractors need to know the specifics of the thin tile they are working with, since LTPTs run the gamut from 3mm to 7mm in thickness, different sizes and with or without fiberglass reinforcement.
“Careful attention should be paid to the manufacturer’s technical manual or installation instructions,” he said, particularly, “areas of use, tools needed, mortar recommendations and detailed installation recommendations.”

Whitfield noted that, “Mortar coverage at all of the edges and corners is critical. The substrates will commonly require a self-leveling underlayment, mortar bed or wall float to meet the industry requirements of substrate variation not to exceed 1/8” in 10’ (3mm in 3m) and 1/16” in 24” (1.5mm in 60 cm) when measured with a straight edge from the high points of the substrate.”

6-TechTalk-0814The thinset is keyed into the substrate and back of the tile then notched with unique trowels like Raimondi’s slant “flow ridge” trowels, which increase the coverage of the mortar between the tile and the properly prepared substrate, he said.

In terms of setting the tiles, Whitfield said that “most mortar manufacturers recommend that thin large format tile floor installations not be walked on within the first 72 hours after installation. A rapid-setting mortar may allow the floor to be opened to light traffic quicker.” Whitfield emphasized that installers and other trades follow these recommendations to a “t.”

Caution counseled by contractors

But some contractors contend that a day or two of training really doesn’t provide all the necessary information to deal with the material successfully – and that there are still a lot of unanswered questions about working with LTPT.

James Woelfel of NTCA Five Star Contractor Artcraft Granite, Marble and Tile, Mesa, Ariz., NTCA 1st vice president and head of the NTCA Technical Committee, asked, “What are the thermal expansion/contraction rates? What are the deflection or torquing rates? How am I – in Phoenix – going to spread 100 sq. ft. of mortar without the mortar skinning over? Mortar manufacturers advised mixing my thinset on the high end of water content. But with that formula, what is the chance that I’ll over-water my mortar to install a 50-sq.-ft. tile 30 feet in the air?”

He continued, noting that the jury is still out about how setting materials can fully support these new LTPTs. “When we discussed the manufacturer’s wish list of standards, including 1/64” in lippage maximum, the question was raised to mortar manufacturers as to what their shrinkage rates for the recommended medium-bed mortar were. Were they more or less than 1/64”? Unfortunately, they didn’t have an answer, nor did they have an answer about how to measure 1/64”. However, that 1/64” was insisted upon so that so the edges will be protected.”

7-TechTalk-0814NTCA Five Star Contractor Nyle Wadford and past NTCA president added, “This is tailor-made for professional contracting firms, especially Five Star contractors. If the product is brought to market the wrong way, failures will increase and the demand will evaporate due to lack of successful installations. We need for this to be successful, but other organizations from around the world are having reservations about installation methods. We just want to see this done correctly.”

Martin Howard of NTCA Five Star Contractor David Allen Company and NTCA 2nd vice president feels more product development is needed on the part of the manufacturers before the product is fully ready for market. “In my opinion the manufacturers have only completed half of the product development process,” Howard said. “Until they have developed a consistently reliable and reproducible system of installation with defined criteria, this product is not market-ready and should not be sold to the unsuspecting public without some warning of the potential risks.”


As stated in part I of our story in the July issue of TileLetter, standards for LTPT are currently under development. Florida’s Whitfield makes the point that it’s not new in our industry to have products in use in the field as standards are developing, as is the current case with premixed grouts, uncoupling membranes, and sealers.

But NTCA’s executive director Bart Bettiga emphasizes that though standards don’t yet exist, there IS some consensus about the materials that is critical for contractors to heed for their own protection.

“Most manufacturers haven’t produced test results that lend confidence to install for any material thinner than 5.5mm for the floor,” he said. “LTPT is groundbreaking technology. We don’t want to get careless and start using this material in a risky way, or in thicknesses less than 5.5mm on the floor until more testing is done and a new consensus is achieved. The tile contractor accepts all the liability in a LTPT project, so we want to be sure contractors are installing tested and approved materials using tested and approved methods and recommendations. “

In fact, a “Thin Tile Position Statement” has been issued by the National Tile Contractors Association (NTCA), Tile Contractors Association of America (TCAA), International Masonry Institute (IMI) and International Union of Bricklayers and Allied Craftworkers (IUBAC). In it, all these organizations “recommend that tile contractors not install thin porcelain tile panels in any thickness less than 5.5 mm for floor installations until standards are developed and consensus is reached that thinner materials may be used on floors. It is our assertion that installations of thin porcelain tiles that are no less than 5.5 mm thick may be successfully accomplished in properly-prepared floor applications with the proper care and processes.

“The tile contractor should be aware that significant training and education are required to successfully install these products and that an investment in tools and equipment is necessary,” the statement continues. “The manufacturer of the tile and setting materials recommendations should be secured in writing prior to installation and the contractor should follow these instructions carefully or potentially be exposed to increased risk and liability.”

Obtaining training, taking care with installations and following manufacturer recommendations set the stage for the greatest success with these new products. And that’s important, because there are many factors that make LTPT an attractive product with a great future: thinner tile; fewer raw materials; lower temperatures and shorter length of time in the kiln vs. traditional porcelains and much less weight to ship, Whitfield said. Plus, “owners like the fewer grout joints, ease of maintenance, and most important the look and thin profile of these tiles,” he said.

Stay tuned for part III later in the year, which explores the topic of LTPT from the setting-material manufacturer viewpoint.

Tech Talk – July 2014


Summertime exterior installations from start to finish

tom_plaskota_webBy Tom Plaskota, Technical Support Manager, H.B. Fuller Construction Products

The arrival of summer often inspires (or requires) homeowners and building owners to beautify their outdoor spaces. A new tile installation can freshen up a pool area, breathe life into a patio or update a building’s façade. While the summer sunshine sparks imaginations, turning your clients’ exterior visions into reality requires special expertise.

Whether remodeling an existing exterior tile installation or starting from scratch, substrate preparation is key. Concrete is the ideal substrate for exterior floor installations, while other firm substrates, including backer board or concrete block walls, can be used for wall installations. When setting tile on existing concrete, make sure you address any liquid-membrane curing compound residues. These products can prevent proper bonding of mortar to the concrete surface, so should be removed through scarification or covered with an appropriate primer.

Laitance – a thin layer of hardened, yet weak, cement – can also affect the substrate’s bonding potential. If laitance exists, the concrete’s surface layer may appear strong and stable, but actually risks causing bond failure. Laitance can be identified by scraping the concrete with a razor or knife. If the concrete scratches or powders, laitance may exist. Formal testing can then be undertaken by measuring the tensile strength of the concrete surface with specialized equipment. The remedy for a weak layer of laitance is removal, which is often done by sandblasting.

1-TT-0714Prepare substrate for a solid foundation

After these preliminary steps, any variation in the substrate should be corrected. Use an appropriate patching compound to flatten the substrate surface. Exterior floors, decks or patios should be sloped to allow for drainage. Concrete on grade should also have a gravel bed or other means of drainage below the slab. Drainage is particularly important for installations subject to freeze/thaw cycling, snow and ice accumulation and/or where snow melting chemicals are used as these conditions can cause degradation over time.

Exterior installations may be subject to changes in temperature and humidity level. This cycle can put mechanical stress on the substrate – which can cause cracking. Waterproofing and crack isolation membranes can help isolate substrate cracks and keep in-plane cracks in the subfloor from telegraphing to the tile. Their waterproofing characteristics can also prevent moisture changes from affecting the substrate.

Combining the right tile with a carefully-prepared substrate helps make exterior installations last. For outdoor floor installations, unglazed tile with its nonslip characteristics is often ideal. All tile used in exterior application should have low porosity. According to industry standards, tile with a porosity of greater than 5% should never be used in exterior applications.


Be mindful of moisture

When your substrate is prepared, your tile is selected, and you’re ready to begin tiling, make sure the installation won’t suffer from excessive porosity in the substrate. Before you begin mortaring, splash water on the concrete. If the water disappears in a few seconds, the substrate is very porous. One way to remedy this problem is to dampen the substrate and allow the surface to dry. Mortar should be applied after the surface dries, but before the moisture below the surface is lost. This will prevent the transfer of moisture from the mortar and result in a proper cure and well-bonded tile. A primer may also minimize the pull of moisture from the mortar into the substrate, ensuring proper curing and bonding.

Moisture can be lost to the atmosphere when the installation is conducted or allowed to cure in direct sunlight on hot, dry days. Excessive heat can prevent fresh mortar from curing properly and developing the necessary strength for long-term installation. On hot days, shield the installation from direct sunlight by tenting. Also, avoid storing unused mortar in direct sunlight.

3-TT-0714Create consistent coverage

To make all of these precautions worthwhile and keep your installation from slumping, sagging or slipping, be sure to achieve proper coverage with a polymer-modified thin-set mortar appropriate for exterior installations. Outdoor installations require 95% coverage – and this requirement increases to 100% with natural stone. Substrate variation, bonding material, trowel selection, and troweling technique are critical factors to consider when trying to achieve proper coverage.

For outdoor environments, use a polymer-modified grout with low water absorption. Consider the use of a grout additive, which can help provide a grout that is stronger, denser, more resistant to water penetration and more flexible. Sealants and caulks can also prevent external elements from penetrating your installation – without changing its appearance.

When working on exterior installations in the hot summer months, you and your crew should take proper precautions not only with the installation, but also with your own health and safety. Make sure you stay hydrated and take breaks as needed. With a healthy crew, a properly-prepared substrate, carefully-selected products and the right installation techniques, you’ll help your clients achieve the outdoor spaces they imagine.

The TEC® brand is offered by H.B. Fuller Construction Products Inc. – a leading provider of technologically advanced construction materials and solutions to the commercial, industrial and residential construction industry. Headquartered in Aurora, Illinois, the company’s recognized and trusted brands – TEC®, CHAPCO®, Grout Boost®, Foster®, AIM™ and others – are available through an extensive network of distributors and dealers, as well as home improvement retailers. For more information, visit

Tech Talk – June 2014

TEC-sponsorANSI requirements for porcelain tile shears are too low

NTCA Recognized Consultant recommends minimum of  300 psi shear rating

1-TT_0614By Tom D. Lynch, CSI

Nearly every ceramic tile floor installation failure that I inspect involves porcelain tile. Perhaps that is due to the popularity of these types of tiles, but a very disturbing trend has emerged that I think warrants discussion. In more cases than not, adequate mortar coverage has been achieved by installers, yet tiles shear off in alarming numbers from the lateral stress that has been applied. Tiles do not let loose from substrates without some sort of stress being applied, usually in the form of a crack appearing somewhere, but I think the extent of these failures can be reduced dramatically.

We all agree that it takes a polymer-modified mortar to hold porcelain tiles in place. The mechanical bond achieved with non-modified mortars is just not enough. The adhesive bond that polymers provide must be added. With this in mind, ANSI insists that a minimum A118.4 porcelain tile shear of 200 pounds per square inch (psi) with a polymer-modified mortar must be obtained for installations of impervious porcelain tile. Do you realize that a good high-quality, non-modified mortar will achieve close to 195 psi on a porcelain shear test? Add about a thimble full of polymer and these mortars could easily hit 200 psi. NOT ENOUGH, I say. For the betterment of the industry, porcelain tile minimum shears must be increased.

2-TT-0614Let me give you another reason why they must be increased. The A118.4 porcelain tile shear test is performed by bonding 2” x 2” porcelain tiles together with a 1/8” offset. After curing, the tiles are sheared by applying lateral pressure and measuring the amount of pounds per square inch that it takes for failure to occur. It must be noted that the coverage of the bonding mortar is basically 100%, yet ANSI A108.5 paragraph 3.3.2 allows only 80% coverage for interior installations of tile (other than wet areas where 95% is required).

In essence, 80% coverage of a 200 psi mortar will only accomplish 160 psi of strength, which is 40 psi short of the minimum requirements for porcelain tiles. At the 95% allowable coverage for interior wet areas and all exterior installations, only 190 psi is obtained. Raising the minimum requirements for the A118.4 porcelain shear is a must, but how much is enough?

Engineering cement/polymer chemistry for thin-set mortars is not as simple as baking a cake. There is a fine point where adding too much volume of polymers with high-flex qualities will greatly increase the adhesive bond but unfortunately will reduce shear strengths. What we do not want is a thin-set modified polymer that will bond to nearly any substrate but cannot hit minimum shear strengths.

3-TT-0614Shoot for 300 psi minimum shear rating

In my opinion, the key is to engineer a polymer modified thin-set that will obtain at least a 300 psi shear rating for porcelain tile. I chose this number for a couple of reasons. First, it greatly increases the current requirement and allows for 240 psi at 80% coverage and secondly it coincides nicely with the newer ANSI A118.15 specification that calls for a minimum 400 psi porcelain shear for many applications.

Porcelain shears of 500-600 psi and more are not unheard of in the industry, but at some point costs must be considered along with performance. I know that many people will complain that the additional cost of a higher-performing A118.4 or an A118.15 mortar for porcelain tiles will be too inflationary, but I say “no way!” Porcelain tiles will likely continue to dominate the industry as the floor tiles of choice, but it is in all of our best interests to lower the number and the extent of porcelain tile failures. A few cents per square foot of additional costs to insist on a better-performing mortar should not be a deal breaker on any project.

By the way, I do not advocate increasing the ANSI A108.5 coverage minimums. Tile installers are, after all, human and insisting on 100% coverage is totally unrealistic.


Tom D. Lynch is an experienced and accomplished technical consultant to the ceramic and stone tile industry. Honored to be one of the first Recognized Industry Consultants by the NTCA, Lynch now has 52 years of experience to draw from. He can be reached at 181 Sunnyside Park Road, Jefferson, NC 28640 or by phone at 336-877-6951. Website is Email at: [email protected]

Tech Talk – Why movement joints and sealants must be installed in tile and stone installations

TEC-sponsorCurrent industry standards and design options

514-pompoBy Donato Pompo, CTC, CSI, CDT, MBA, Ceramic Tile and Stone Consultants (CTaSC); University of Ceramic Tile and Stone (UofCTS)

Many end users don’t want movement joints because they think they are distractive and ruin the appearance of their tile installation. So why should tile installers make sure that movement joints are installed in all of their tile installations?

The short answer is because industry standards say that all tile installations must have movement joints. If you don’t install movement joints, and there is some problem with the tile installation, then the fingers will be pointing your way and you will be held responsible even if the problem isn’t directly related to the lack of movement joints. Lack of movement joints can be a contributing factor to many different types of tile failures, so it’s not worth the risk to exclude them from your installations.


Cracked grout due to missing transition movement joint.

All tile and stone assemblies move in one way or another, whether due to thermal movement, moisture movement, shrinkage, freezing, or dynamic structural movements. To ensure a long-lasting installation, it’s important for architects to specify and provide the requirements for movement-joint design and placement, and to specify the correct type of sealant (caulking) for filling those joints. When there isn’t an architect – and the tile installer is determining how to install the tile – then it becomes the tile installer’s responsibility to specify and install the movement joints or to find someone else to specify them.


Tented glazed tile floor

“Movement joint” is a general term used for all types of joints seen in construction materials that control and allow movement. Most commonly we refer to these joints as either “expansion joints” or “control joints,” but there are various categories of movement joints. Generally they contain an appropriate pliable sealant for the intended application that is often referred to as a soft joint. Movement joints allow for the material in which they are placed to move without restraint, and they control where the movement manifests, avoiding random cracking in finish materials. An example would be the joints or separations in a concrete sidewalk. If there were no movement joints in the concrete sidewalk, then it would crack at some random point as it is subjected to shrinkage (contraction) as it cures, or subjected to expansion when it is exposed to moisture or heat, and then contraction again as it dries and cools.

514-tt-3I have seen tile floors without adequate movement joints where a portion of the floor was literally tented (debonded and raised) several inches off its substrate during the heat of the day, but laid flat at night when it cooled down. To see how small horizontal movements can result in exponentially larger vertical movements, take a 48’ (1219 mm) metal ruler and lay it on a horizontal surface. Restrain one end of the ruler and move the other end toward the center 1/8” (3.2 mm), and you will see a 2” (51 mm) rise at the apex of the ruler. In effect, this is what happens to tile floors when they tent. They are constrained at their perimeters with no movement relief and the tile expands.

514-tt-4Guidelines for movement joints

The Tile Council of North America (TCNA) provides general movement joint guidelines for tile and stone applications in its TCNA Handbook for Ceramic, Glass, and Stone Tile Installation. The guidelines are listed under EJ171 Movement Joint Guidelines for Ceramic, Glass, and Stone section. When there isn’t an architect on the job then the tile installer should refer to these standards to determine where to install movement joints. If there is an architect and they haven’t specified movement joints, then the tile installer should submit an RFI (request for information) to ask for the movement-joint layout and design.

The general rule is that movement joints should be placed at the perimeters of tile installations and at all transitions of planes or transitions to different materials, as well as within the field of tile. Inside and outside vertical joints on framed walls should have movement joints and should not be hard-grouted. Bathtub or shower receptor to wall transitions should have a movement joint. In wet areas, movement joints are important not only to control movement, but they act as a water-stop at those transitions, providing another layer of protection against potentially costly water damages.

TCNA EJ171 states that movement joints for interior applications should be placed at least every 20’ to 25’ in each direction unless the tile work is exposed to direct sunlight or moisture. In that case, movement joints should be placed at least every 8’ to 12’ in each direction – the same for exterior applications.

EJ171 states that all underlying movement joints in the substrate need to continue through the tile assembly. This means that in addition to honoring the substrate movement joints, the tile assembly needs additional movement joints within its assembly. If there is a mortar bed over the substrate, then the movement joint has to be continuous through it to the tile surface, which is considered an expansion joint. If the tile is being bonded directly to the substrate, and there is no substrate movement joint continuing up from beneath, then it is called a generic movement joint. The generic movement joints are often the same width as the grout joints if they were designed to work at that width. The movement joint widths within the tile work should never be narrower than the substrate joint on which it is placed.

Membrane cautions

Some manufacturers of ANSI A118.12 crack-isolation membranes allow their membrane to cover non-structural movement joints (joints that only move horizontally, but without any vertical displacement) such as saw-cut or cold-control joints, even though TCNA does not recommend it. Structural expansion joints can never be covered with membranes, since the vertical displacement cannot be mitigated with a crack-isolation membrane. Crack-isolation membrane manufacturers require that movement joints are installed within the tile assembly installed over their membrane. Some manufacturers allow the movement joints to not line up exactly over the substrate control joints. Each manufacturer of crack-isolation membranes may have different recommendations and limitations, so it is always important to follow manufacturers’ instructions.

TCNA F125-Partial and F125-Full Crack Isolation Membrane details provide guidelines for isolating non-structural cracks with an ANSI A118.12 crack-isolation membrane. This detail recommends that a movement joint be placed at one or both ends of the tile, parallel to the crack which is bridging the underlying shrinkage crack or non-structural control joint, as recommended by the membrane manufacturer.

Sealants for soft joints

The type of sealant (caulking) used to fill movement joints is critical to the success of the tile installation. TCNA EJ171 states that an appropriate ASTM C920 sealant must be used to fill movement joints of all types. An ASTM C920 sealant includes high-quality silicone, urethanes, and polysulfide sealants. These types of sealants are normally rated as highly weather resistant with high-elongation properties, and high-adhesion characteristics that come with 20-year commercial warranties. Too often we find installers using some type of acrylic, latex, or siliconized sealant, because they are easier to work with, but these sealants have very low performance values and basically no warranty.


Using sealants that are not suitable for foot traffic may may be dangerous to those who wear high heels.

Different sealants have different physical properties and performance capabilities. EJ171 provides guidelines and the nomenclature for determining the appropriate Type, Grade, Class and Use sealant for the intended application. For instance, some sealants are not suitable for foot or vehicle traffic, so you must use a “Use T” sealant for those applications. A traffic sealant should have a Shore A Hardness of 35 or greater, which is critical because otherwise it would be dangerous to those who wear high heels. Some sealants can’t be used in a submerged application and some can’t be subjected to certain chemicals. Not all ASTM C920 sealants are compatible with natural stone and could cause the stone to stain. Some sealants require the surfaces to be primed after cleaning the joints and prior to installing the sealant.

Movement joint aesthetics

Movement joints are a necessary part of tile and stone installations and can even accentuate design features, rendering the joints unnoticeable, when specifiers take the time to design the movement joints into the installation.

Manufacturers of one-part silicone sealants have a broad range of colors available; custom colors are generally available to match the grout. Two-part urethane sealants can be mixed on the job by experienced sealant installers and can easily match the color of the tile grout. Movement joints placed more frequently in the installation can be narrower to match the width of the grout, also making them less noticeable. If your tile pattern has staggered joints, you can use the staggered-grout joint (referred to as a saw-tooth joints or zipper joints) as a generic movement joint to make it less noticeable. When done well, movements joints are not noticeable and can enhance the features of the installation.


All tile and stone assemblies move in one way or the other, whether due to thermal movement, moisture movement, shrinkage, freezing, or dynamic structural movement. To ensure a long-lasting installation, install movement joints and use the correct type of sealant (caulking) for filling those joints. The key to a successful tile and stone installation is to follow industry standards.


Donato Pompo, CTC, CSI, CDT, MBA, is the founder of Ceramic Tile and Stone Consultants (CTaSC), and of the University of Ceramic Tile and Stone (UofCTS). He has more than 35 years of experience in the ceramic tile and stone industry from installation to distribution to manufacturing of installation products. Pompo provides services in forensic investigations, quality control (QC) services for products and installation methods, training programs, testing, and onsite quality control inspection services. He received the 2012 Construction Specifier magazine Article of the Year Award. Pompo can be reached at [email protected]

Tech Talk – The price of beauty: addressing challenges of glass tile

TEC-sponsorGlass tile continues to grow in popularity for both aesthetic and functional reasons. It provides an elegant, upscale look, and its composition makes it easy to clean and maintain. Because it can contain recycled glass, glass tile is also a sensible choice where sustainability is a concern.


By Tom Plaskota, Technical Support Manager, H.B. Fuller Construction Products

However, the same attributes that benefit the end user of glass tile can also challenge its installer. For example, its imperviousness makes it ideal for wet areas like pools, showers and backsplashes, but also makes it difficult to bond. The translucence of some glass tile gives it a highly desirable appearance, but requires that the installer take extra care to create a uniform look when applying mortar and grout. To help the end user reap the benefits of glass tile, here are some proven installation strategies.

Mind the mounting

If glass mosaic tiles are specified, keep in mind that they are often pre-assembled into sheets with some type of mounting material. Before installing back-mounted mosaic glass tile in wet or submerged applications, check with the glass tile manufacturer to ensure the back mounting is suitable for wet areas. The adhesive used to bond the tiles to the mounting material may be water sensitive, resulting in bond issues in wet environments.

Mortars: bond and color

For any glass tile installation, you will need to address potential bond problems with your mortar selection. Glass tile’s lack of porosity requires the use of a latex-modified thin-set mortar, but not all modified mortars are suitable for glass tile. Some manufacturers have specific mortars designed for use with glass tiles.

With translucent tile, mortar color matters. White mortars provide a bright, consistent backing for translucent or transparent glass tile. They also minimize the effects of high alkalinity found in gray mortars that can result in glass tile discoloration and loss of bond strength.

However, the TEC® brand of setting materials offers additional aesthetic and functional options for bonding glass tile. To install glass tile, you may use TEC® AccuColor® Unsanded Grout (white cement-based colors only) mixed with XtraFlex Acrylic Mortar Additive. AccuColor® Unsanded Grout comes in a variety of white cement-based colors, which can enhance the final appearance of clear or translucent tile. Use of the mortar additive, rather than water, for mixing produces extremely high bond strengths.


For a consistent appearance, be sure to flatten notch trowel ridges before setting translucent or transparent glass tile. Voids or gaps in the mortar can show through the tile.

Mastic is typically not recommended for glass tile. However, if the glass tile is pre-bonded to a colored backing, mastic may be the best option, because mortar can cause degradation of these backings. In dry areas, mastic is the preferred setting material for these types of tiles.

Room to move

Expansion joints also contribute to successful long-term installations of glass tile. Glass tile has a high level of expansion and contraction. Proper placement of expansion joints prevents the development of resulting stresses that disrupt the bond. For example, problems have occurred when dark glass tiles were installed on exterior walls without any expansion joints. When subjected to direct sunlight, the dark glass warmed and expanded. Without flexible expansion joints to accommodate the movement, the tile lost bond and “tented” up off the substrate. For recommendations regarding expansion joints, refer to Installation Method EJ171 in the TCNA Handbook or ANSI Specification A108.01, Sections 3.7 through


Glass tile can have specific requirements for grout to prevent surface scratching and ensure long-term performance. Check with the glass tile and grout manufacturer for compatibility.

Grout is an equally important consideration for a successful glass tile installation and requires consultation with glass tile and setting material manufacturers. Some glass tile can be susceptible to surface scratching when installed with sanded grouts and therefore requires the use of unsanded grout. Other glass tiles are compatible with sanded grouts. The same holds true of epoxy grout: some glass tile manufacturers recommend installing with it and some do not. In addition to traditional cement and epoxy grouts, some grouts, like TEC® Design FX™, are specifically formulated to be functionally compatible with and enhance the appearance of glass tile.

As you can see, there are some aspects of glass tile installations that are universal and some that vary by manufacturer, and even product line. Pre-installation communication with your suppliers and/or manufacturers is necessary to overcome these complexities, ensure successful installations and minimize callbacks.


Some grouts, like TEC® Design FX™, are specifically formulated to be functionally compatible with and enhance the appearance of glass tile.

TEC®, AccuColor®, XtraFlex™, and Design FX™ are trademarks of H.B. Fuller Construction Products Inc. 

Tech Talk – Tile industry-recognized certification can make the difference in your business

TEC-sponsorAccept no substitutes – CTI and ACT are the only officially recognized certifications in the tile industry

I just returned from the International Surface West event in Las Vegas. It was clearly evident that all the organizations that represent the floor-covering industry are emphasizing the importance of quality installation as an essential component to the growth of their respective industries. Throughout the show floor, you could find training seminars, live demonstrations, and certification testing taking place. This is a really good thing to see.


By Bart Bettiga, executive director, NTCA and CTEF and member of ACT Taskforce

As a leader in the tile industry, I want to point out something that I think is very important about the word CERTIFICATION. It can be used in a variety of ways, and the tile industry needs to address this word immediately, so that we understand the difference as it relates to who is qualified to do what type of work in commercial and residential installations.

There are training programs currently being offered by some organizations that are entry-level relating to installing tile. At the end of the training session, “certifications” are given that the installer has successfully completed this program. There are also proprietary manufacturer training programs and online, knowledge-based seminars that offer “certification” for completing the course.

I want to be very clear in my point here. These are great things to see happen. Anyone who is offering training and increasing knowledge for the sale or installation of tile and stone is contributing to our industry growth.

All “certifications” are not created equally

But – and this is a big but – if these programs are marketed in the incorrect way, then all the good they have done is quickly swept away. This is, in fact, dangerous for our industry.

This is why the tile industry has taken a strong stance on the word CERTIFICATION. This is why we have written clear language related to qualified labor in the TCNA Handbook and in Master Specifications. We have to differentiate the installers that are truly qualified from those who are not.

TT-1The ONLY OFFICIAL certification currently being recognized by the tile industry – in accordance with standards set out by the tile industry – are the CTEF Certified Tile Installer (CTI) certification and the Advanced Certifications for Tile Installers (ACT) Program. The language is clear. In addition to these two certifications, we recognize Department of Labor-approved apprenticeship programs as a way to qualify installers as well.

Why is tile so different and why are we so serious about this? For one thing, tile installations are often designed to be permanent, often installed in wet areas, and at times with other living space underneath the installation. It is very expensive to replace, and other products have to be moved and can be damaged when replacement has to take place.

Tile and stone comes in different sizes, shapes, and formats, is extremely challenging, and not forgiving in regard to installation. It needs to be looked at differently than other floor coverings when considering who is qualified to perform the work.

Our own industry recognized that even a rigorous certification test like the CTI exam the CTEF offers was not enough. That is why we partnered with all the leading tile industry trade associations to develop the ACT program – so that we go further into specific skills such as shower pans, mudwork, waterproofing and crack isolation, and large-format tile. We will be adding grouting applications and thin-tile installation very soon.

Invest in industry-recognized certifications: CTI and ACT

To every tile installation contractor who reads TileLetter regularly I am telling you today: contact the CTEF or your local union representatives to discuss the official, tile-industry-recognized CTI or ACT programs. If you are already a CTI, you need to make plans to become ACT-certified. You need to differentiate yourself from the competition. And you definitely need to understand the difference between these certifications and others that are being offered and rewarded out there.

I can’t think of anything more damaging in our industry than a beginning tile installer getting hired instead of a more qualified tile contractor because they have a piece of paper that says they are “certified” in a program that the tile industry doesn’t recognize. How would a consumer or builder know the difference? They wouldn’t! You need to get officially certified in a program our industry supports and recognizes, and you need to understand how to explain that to your customer.

Certification is here to stay. The specifications are starting to call for it. Our industry needs it; the quality tile contractors need it as well. Contact us immediately to discuss how we can help you set yourself apart from the competition.

[email protected]

Tech Talk – January 2014

TEC-sponsorInstalling ceramic tile, glass tile and stone in interior wet areas

Slope, weeps, and flashing are key to managing water and avoiding failures

Donato PBy Donato Pompo, CTC, CSI, CDT, MBA,
Ceramic Tile and Stone Consultants (CTaSC),
University of Ceramic Tile and Stone (UofCTS).  

Exterior decks and balconies, and interior showers and bathrooms have historically been problematic areas for the installation of ceramic tile, glass tile, stone tile and other stone products. Typically problems are due to installer error, such as not using appropriate materials for those applications, or not having clear enough specifications. In each case it is the result of not following industry standards. Exploration into the intricacies of exterior decks and balconies can be an entire article in itself, but for this story, we will focus on interior showers and bathrooms.

Industry standards are created by industry consensus groups consisting of installers, producers, and industry experts through organizations such as ANSI (American National Standards Institute), TCNA (Tile Council of North America), ASTM (America Society for Testing and Materials) or ICC (International Code Council).  These consensus group members combine their many years of experience with science to establish standards so problems and failures can be avoided and not repeated.  Thus if standards are not followed then known potential problems can’t be avoided.

As a forensic investigator for over 11 years, I have investigated many failed interior showers and bathrooms. I have found that the common denominators to tile and stone failures in these applications were the lack of proper slope, plugged weep holes, and inadequate flashing to contain or manage the water that resulted in various types of damages.

Managing water volume


First, consider the volume of water that showers are subjected to on a daily basis. Since these areas are likely to be subjected to more water than a typical roof is subjected to annually, it is imperative that extra care and attention are spent on specifying and constructing them. This is accomplished by properly managing the water so it is controlled and safely evacuated from those areas.

Lack of adequate slope is a common problem in interior wet horizontal applications such as shower floors, shelves and seats. It is very clear in the tile and stone industry standards, as well as in the Uniform Plumbing Code (UPC), and in the IRC (International Residential Code) or IBC (International Building Code) building codes, that the slope to drain, or away from the building, should be a minimum 2% slope. That calculates to 1/4” per foot (6 mm per 305 mm). UPC says the slope to drain in a shower must be a minimum of 1/4” per foot (6 mm per 305 mm), but not more than 1/2” per foot (13 mm per 305 mm).

Not only is it important for that slope to drain to be at the surface of the tile or stone, but it is critical that the minimum 1/4” per foot (6 mm per 305 mm) slope to drain is at the surface of the waterproof membrane or drain plane. Drains come in two sections. Where the drain clamps down on the waterproof membrane below the surface of the tile assembly, there are weep holes in the drain assembly, so that any water that migrates to the waterproof membrane can then evacuate into the drain through the weep holes.

Problem #1: Improper slope to the drain


There are  three common problems that we run into. First, the waterproof membrane is not properly sloped to the drain. In a shower this can result in the tile mortar bed staying constantly damp, which creates a musky odor in the room, or it may cause a stone or tile floor to look wet. Excessive moisture might result in the stone spalling (deteriorating) and/or staining.   Sometimes we find that the waterproof membrane is flat or even negatively sloped away from the drain, or that there are low spots on the membrane surface where water collects.

Problem #2: Plugged weep holes


The second common problem is drains with plugged weep holes.  Industry standards state that the weep holes are to be covered with pea gravel or with a plastic weep hole protector to make sure the weep holes stay open. Often this weep hole protection is left out, and mortar is placed over the weep holes, plugging them. Thus, if the waterproof membrane is properly sloped to drain, the water cannot escape into the drain. Again, this can result in the tile mortar bed staying constantly damp, which results in the musky odor in the room, a wet-looking floor or stone spalling or staining.

The term “spalling” refers to the deterioration of the surface of a stone. It is the symptom of a stone being subjected to excessive moisture over time. Spalling is typically caused by moisture migrating from the stone’s underlying substrate up through the stone to its surface where the moisture evaporates. As the moisture travels from under the stone through the cementitious materials, and through the stone itself, the moisture picks up various minerals (salts) which dissolve in the moisture. When the moisture reaches the surface of the stone it evaporates and the minerals precipitate into a solid again.  This expansion or crystallization of the mineral, referred to as efflorescence, causes the surface of stones to deteriorate to some degree.

Whether it is a shower or an exterior deck or balcony, the waterproof membrane surface must be sloped to drain or away from the building. Shower pans or receptors are supposed to have a pre-sloped mortar bed installed over the base substrate before installing the waterproof membrane. The pre-slope needs to have a minimum slope of 1/4” per foot (6 mm per 305 mm).

Problem #3: Membrane breaches3-techtalk

That brings up the third common problem that we find in showers: waterproofing or vapor retarders that are not complete or continuous. They tend to lack flashing at transition areas. Considering the potential collateral damages a defective balcony can develop, it is important to construct it like a big shower pan. Assuming that the deck has been properly pre-sloped, the waterproof membrane must continue, or be flashed, up the wall at least 3″ (76 mm) above any thresholds to prevent water from causing any potential collateral damages. All seams, penetrations and transitions must be properly waterproofed, flashed and sealed with a sealant. These are the areas that are most vulnerable to having problems, so they need to be given the extra attention to ensure they are installed correctly. The waterproof membrane should never be penetrated, unless it is unavoidable, and then the penetration has to be properly flashed and sealed with the appropriate sealants to ensure it will never leak.

Often we find that decks are sloped to their outer edge without any type of gutter or drain. The water drains over the side of the balcony and eventually results in staining along the siding, or staining and spalling the stone if there is stone siding. The latest trend is to use trench or linear drains that work very well and can be installed at the perimeters of decks or showers.


So how can a tile installer make sure that showers are given the attention they need to avoid failures? It is the same old answer.  Follow industry standards and manufacturers’ directions. It doesn’t matter who is at fault when there is a problem; everyone ends up paying – either in time to defend themselves, money to fix the problem or with their reputation. So it is in everyone’s best interest to make sure that tile and stone installations are done properly. (Editor note: please visit for the full text of this story, which also addresses exterior installations).

Ceramic Tile Consultant, Donato Pompo, CTC, CSI, CDT, MBA, is the founder of Ceramic Tile and Stone Consultants (CTaSC), and of the University of Ceramic Tile and Stone (UofCTS). Donato has over 35 years of varied experience in the ceramic tile and stone industry. CTaSC provides services in Forensic Investigations, Quality Control Services for products and installation methods to include writing specifications, training programs, testing, and on-site quality control inspection services. CTaSC is a professional consulting business comprised of accomplished ceramic tile consultants, stone consultants, ceramic tile and stone installers, architects, engineers, general contractors, construction scientists and other industry specialists and experts conveniently located throughout the US and Canada. You can reach Donato by visiting the company website at, emailing [email protected] or calling 866-669-1550.

TechTalk – December 2013

Spot-bonding to cure an uneven substrate is a no-no that even a customer can recognize

Unacceptable methods and unskilled installation set the stage for future problems

By Lesley Goddin

Sometimes the correct and incorrect ways to install tile are so clear and intuitive that even a non-tile- professional, new homeowner, realizes something is amiss, even if “reputable” builders or less-informed tile installers do not.

Such is the case of a soon-to-be- homeowner, Sean Hobbs of Oviedo, Fla., and his wife Kimberly, who elected to inform themselves about materials and installation techniques as their home was being built. Some techniques seemed questionable, and Hobbs contacted NTCA for guidance in the matter.

“It seems that the voids left by the patty technique would be undesirable and potentially weak areas should they get knocked,” the homeowner astutely observed.

“It seems that the voids left by the patty technique would be undesirable and potentially weak areas should they get knocked,” the homeowner astutely observed.

Hobbs wrote, “The tile on the vertical walls of the showers are being applied using a ‘patty’ technique. We wouldn’t have been aware of this except that the water proofi ng Hydro Guard 1 was left unfi nished on one of the showers and the tilers needed to remove the tile to correct this. Not a single one broke. Mike Holmes of Holmes on Holmes and Holmes Makes it Right on HGTV described tile coming off easily and without breaking as a sign of poor work, so from this I felt the work wasn’t being
done well.

“It seems that the voids left by the patty technique would be undesirable and potentially weak areas should they get knocked,” Hobbs astutely observed. “I thought the only technique was to apply the thinset to the walls, use the notched trowel to comb the thinset, place the tiles, and try to get as close to total surface contact with the back of the tile. Some even recommend taking off every fifth tile to confirm this by inspecting the back. Others recommend a very thin ‘back buttering’ of the tiles to be sure of this total contact.”

Hobbs is speaking the language of the skilled tile installer here! He scoured the internet for proper tech- niques, which he shared – to no avail – with his builder. He revealed, “My wife and I were told by the builder that the directions on the bag of thinset were merely ‘recommendations.’”

The builder insisted that he is following best practices and lets “’building science’ guide his build- ing materials and their installation,” Hobbs said. “As it stands now, he is accepting the tiler’s reasoning that the DUROCK® and PermaBase® walls – which the same tilers themselves installed just a few weeks ago – are a bit off and they need to use this patty technique to perfect the tile so that the look is right.” The builder main- tained that using the aforementioned proper method would not allow the installers to fine-tune their placement to achieve a good look due to the “suction” of the tiles.

Shoddy work on display

Hobbs observed that “such a small amount of thin-set patties were utilized, that tape and even screws (piercing the waterproof membrane) were used to hold the tiles up and prevent them from sliding."

Hobbs observed that “such a small amount of thin-set patties were utilized, that tape and even screws (piercing the waterproof membrane) were used to hold the tiles up and prevent them from sliding.”

Hobbs observed that “such a small amount of thin-set patties were utilized, that tape and even screws (piercing the waterproof membrane) were used to hold the tiles up and prevent them from sliding. It is my opinion that one of the reasons the builder allowed this inferior work to be performed was to get the home ‘Parade Home-ready’ since our home – with the builder’s sign prominently displayed – was to be featured for a local annual public display of new and renovated homes.”

Hobbs sought recommendations from TCNA and received information from industry consultant Dave Gobis which included ANSI tile setting standards, and two articles – one of which, “Dots, Spots, Dollops and Whatever,” appeared in the April 2013 TileLetter.

The builder’s solution to the voids under the wall tile was to pour a slurry behind the installed tiles to fill in the spaces.

The builder’s solution to the voids under the wall tile was to pour a slurry behind the installed tiles to fill in the spaces.

“While the patty work continued, the builder was searching around to find some other ‘expert’ to refute Mr. Gobis’ perspective because the builder was sure it was simply a different technique,” Hobbs added. “Most of the remediation (certainly not my first choice) was to grout all but the top tiles, remove the top tiles, pour a slurry to fill the voids while gently tapping with a rubber mallet to help the slurry settle, and call it done.

“The builder states that he has filed paperwork with his insurance company just in case there are any future problems with this tile install for our home,” Hobbs said.

In addition to the wall tile fiasco, Hobbs specified and paid extra for Ditra uncoupling membrane he’d seen recommended by Mike Holmes. Floors in his former home had cracking tiles and he wanted to eliminate this in the new place.

“What we found by dragging a long thin metal rod lightly across our floors is that there are numerous and large areas of tile floor with 12”x12”, 12”x24” and 24”x24” in a Versailles pattern that are hollow underneath,” Hobbs said. “Our builder’s response when shown and allowed to hear this was ‘it’s hard to lay tile and get it just right.’ We have ongoing issues after moving in June of 2013.”

Bringing his concerns to the NTCA, he asked, “Am I being overly concerned here? Are these appropriate issues to bring up? Should I consult a local tile professional, possibly one in good standing with the National Tile Contractors Association organization, to get a second opinion?”

NTCA responds!

Well, dear reader, I can imagine that you are thinking, “You SHOULD be concerned, Sean!” and “Good eye!” Here’s how Gerald Sloan, NTCA presenter and technical con- sultant, responded:

“I highly recommend choosing a tile contractor that is a member of the National Tile Contractors Association,” Sloan said. “Please visit our website, then go to member locator to find a member contractor close to you.

“As a member, the tile contractor is privy to yearly updates on industry- recognized installation standards and cautions, in addition to product limitations,” Sloan said. “Another great member benefi t is technical sup- port that comes from our Technical
Committee where issues that concern tile contractors are discussed with efforts to avoid actions that have caused tile installation-related failures. A member who is active in our association is well-armed to avoid potential failures due to inappropriate installation practices. We wish all tile contractors would be a part of the NTCA, so we could eliminate all installation related failures.”

Sloan addressed the folly of incorrect spot bonding especially to correct uneven substrate conditions.

“As for your question related to spot bonding the tile to correct out- of-plane or out-of-plumb wall substrate conditions, this is high risk for a failure due to several factors,” Sloan said. “One is, as you men- tioned, impact loads. Those areas behind the tile that do not have coverage are much more likely to break if an impact condition should occur.

“Another potential problem is in a wet environment such as a shower; open pockets can harbor dampness much longer, and the body oils and dirt from your body can penetrate through the tile and grout joint – even if it has a quality sealer on it,” Sloan said. “Over time, this mate- rial may accumulate and become food for B.O.G (biological organic growth) or mold.

“The other reason we should not spot bond with common multipurpose thin-set setting materials is because they have a high rate of failure due to product shrinkage,” Sloan added. “The multipurpose thin-set products we work with most often are not designed to be built up to more than 1/4” thickness as measured after the tile has been installed – remember it’s called thinset. If it exceeds maximum allowable finished thickness, it has been proven to fail due to shrinking as it cures.”

The Tile Council of North America Handbook for Ceramic, Glass and Stone Tile Installation has a generic caution given in the note section (p. 17 in the 2013 edition) about not using medium bed mortars to true-up underlying substrates, Sloan said. Additional recommendations for mortar use are listed on page 35 of the Handbook.

The ANSI Standards, on page 88, in section in the Definitions of Latex-Portland Cement Mortar, state: “Modified dry-set mortars are designed as direct bond adhesives and are not intended to be used in truing or leveling underlying substrates or the work of others.”

The homeowner said, “My wife and I were told by the builder that the direc- tions on the bag of thinset were merely ‘recommendations.’”

The homeowner said, “My wife and I were told by the builder that the direc- tions on the bag of thinset were merely ‘recommendations.’”

Bart Bettiga, NTCA executive director, jumped in on the discussion. “We don’t specifically have a section that addresses spot-bonding or pattycaking because, until recently, we were not aware that this practice was gaining steam,” he said. “We intend to alert our ANSI and Handbook committees that we may need to go even further to address this.

“There is a reason why patching and leveling products are made; because they are designed for these purposes,” Bettiga added. “The mortars that are manufactured to be used to direct-bond tile and stone are formulated to be spread to a certain thickness. When you deviate from this intention, you defeat the intended purpose of the products. We are not aware of any thin-set manufacturer that would recommend or warranty their products to be used in this fashion.”

Instead of using mortar to even up the substrate, Sloan said, “If the framing is out of plumb, framing should be corrected by shimming, sistering, scabbing, or total removal and replacement. Do not true up with thinset because the thicker places shrink more than the thinner places, thereby creating stresses that often cause the loss of bond to the tiles in random areas. The American National Standard Institute has a thin-set coverage requirement under A-108 which mandates wet area tile installation thin-set setting coverage to be 95% – 80% coverage for dry areas – with all edges and corners covered.”

Spot-bonded tiles came off the wall easily and intact - evidence of badly-bonded tiles.

Spot-bonded tiles came off the wall easily and intact – evidence of badly-bonded tiles.

This game of “patty-cake” played by the builder is setting the ground- work for future problems, ones that he has opted to cover by insuring the work instead of doing it right from the beginning.

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