Tech Talk – August 2015 “Green Issue”


Encountering steel trowel-finished concrete floors that do not have a fine broom finish

lynchBy Tom D. Lynch, CSI

Every thin-set, applied-tile installation method over concrete substrates found in the TCNA Handbook for Ceramic, Glass and Stone Tile Installation calls for floors to “have a steel trowel and fine broom finish free of curing compounds.” When encountering floors that do not meet this criteria, a myriad of unanswered questions immediately arises:

What process should be used to scarify the floor to make it comparable to a fine broom finish, e.g. acid etching, grinding, or shot blasting? Is there an industry-acceptable alternative to a fine broom finish? If so, what is it? There is also the issue of possible residue left from curing compounds, which the concrete contractor may or may not admit to using. Lastly, who is to pay for prepping the surface to comply with the architect’s specifications and the TCNA Handbook?

(Ed. note: NTCA, in conjunction with ASCC, NWFA and FCICA issued a joint position statement: Division 3 versus Division 9 Floor Flatness Tolerances, Position Statement #6. This statement addresses some of the questions raised in this story. It is contained in the 2015/2106 NTCA Reference Manual, which can be ordered at

Good questions all, but why do floors scheduled to receive ceramic tile hardly ever have a fine broom finish in the first place? There are many possible answers to this question. The fine broom finish requirement appears in the 09300 tile specifications, but one must usually refer to the selected TCNA method of installation to see it spelled out in writing. Concrete contractors most likely do not read the tile specs when bidding a job and they rarely own a TCNA Handbook. Many times room finish schedules calling for vinyl composition tile or carpet that do not need fine broom finishes may get upgraded to ceramic tile long after the concrete has been poured. Another scenario might be that slabs get poured in large open spaces long before interior walls get erected, so mapping out areas that are to receive tile becomes difficult and time consuming for the concrete contractor. No matter what the reasons, a fine broom finish must be applied to freshly-poured concrete and that means it is/was the responsibility of the concrete finisher to apply; not the tile contractor.

CSP-kitLet’s get back to the issue of what can be done to make a smooth steel-troweled finished slab acceptable to receive tile. I have a suggestion. The International Concrete Repair Institute (ICRI) has developed a Concrete Surface Profile (CSP) system to shed some light on concrete surface preparations. The CSP “kit” contains a set of nine samples of different degrees of scarification that can be obtained by shot blasting concrete floors.

shotblastingmachineShot blasting machines can utilize different-sized steel shot that get blasted onto concrete floors under varying degrees of force for different lengths of time to develop a desired profile.

Slab texture is of paramount importance to enhance good bond performance for thin-set mortars and my experience has shown that a CSP-3 profile closely resembles the texture that a fine broom finish on freshly poured concrete will provide. As an added benefit, shot blasting can remove curing compound residues that might be present on the surface of the concrete.

Concrete Surface Profiles are currently being used to prepare concrete floors for many types of floor finishes such as trowel applied epoxy resins. These CSP profile ratings are something that can be architecturally specified, so maybe it is time to get our industry involved and officially include them in thinset-applied ceramic tile installations. It would definitely reduce installation failures, and that is really what this article is all about!


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 53 years of experience from which to draw. 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 – July 2015

TEC-sponsorBuilding the perfect shower

By Lesley Goddin

Installing showers are one of the most frequent jobs encountered by a tile setter – and one of the most challenging. Managing water issues imparts another dimension to the USUAL demands of tile installation projects. In this edition of Tech Talk, we connect with some tile contractors who are experts at shower installations to learn about pitfalls of these projects and how to overcome them with beautiful results.

Top challenges

John Cox, owner of NTCA Five Star Contractor company Cox Tile in San Antonio, Texas, noted that logistics – especially getting materials to higher floors – take some planning. “Most residences do not have elevators, so scaffolding and ladders are the only means of getting materials to the bathroom.”

1-tt-0715Weather also is a contender for “muddying up” bathroom installs. That’s because to achieve the stunning bathroom effects it produces, Cox Tile muds its walls using the one-coat method, which is made all the more difficult when weather conditions are wet and humidity is high.

Both Cox and Buck Collins of Five Star Contractor Collins Tile and Stone in Ashburn, Va., cite walls that are neither plumb nor square as being problems on the job. Collins says this challenge is exacerbated by today’s use of “large-format tiles, seats and recessed niches,” and attacks the problem by plumbing the walls before rebuilding them. Cox added that his company is “exerting more labor and energy correcting workmanship issues,” such as lack of skilled labor and costs to create a plumb and square canvas on which to install tile. “We have to use a scratch and brown coat to our walls due to the depth when they are out of plumb or out of square,” Cox said.

When working with walls that need flattening, Joe Kerber, owner of Five Star Contractor Kerber Tile, Marble & Stone, Inc. from Shakopee, Minn., said that 1/16” sheetrock furring strips, available at big box home centers, can be used to fur out walls that are not flat or straight. He insisted, “Make sure that the walls you are going to set tile on are flat, not necessarily plumb.”

Kerber also noted that pitch to the drain can be a challenge when working with barrier-free showers. (see Kerber’s By the Book article on curbless showers in this issue.) “Sometimes we have to reframe the floor system to accommodate the correct pitch for the particular room,” he said.

Another issue that comes with shower installs is seats that are prone to leaking, Collins said. To alleviate this problem, Collins uses “pre-formed seats and niches to elevate any potential issues.”

Martin Brookes, owner of Five Star Contractor Heritage Marble & Tile, Inc., in Mill Valley, Calif., shared that his company has discovered that sometimes showers “will be redesigned after bid stage to a steam room without the owners being aware of the significant up charge and design changes to accommodate this scenario.”


Top tips for shower installs

Much of the wisdom around shower installs centers on waterproofing – clearly a key component to any successful shower or steam room project.

Cox recommended that contractors, “Understand and know the value in waterproofing. Especially niches, benches, seats, jambs and window frames. These are long-term problematic areas that do not get treated properly. They show up later down the line and are generally costly problems to correct.” Brookes declared that “Waterproofing the shower enclosure and shower pan is key in longevity of the shower stall. It’s critical to identify ahead of time if you need a trench drain instead of a traditional shower drain. Not every application will allow for the use of a trench drain with a barrier-free walk-in type shower stall. Sometimes the floor will need to be re-engineered to accommodate this application. Steam room applications will require a whole different approach and a different set of specifications to make it fully functional.” And be sure you “have proper pitch to the drain on all horizontal surfaces,” Kerber said.


Brookes confirmed, “The importance of waterproofing all niches and penetrations should be understood. All mounted accessories should be considered, and appropriate backing installed before preparation work begins. Follow the rules and understand the waterproofing requirements and your installation will survive for many years to come.” Brookes underscored the importance of reading and clearly understanding TCNA standards, as well.

Kerber pointed out, “Use correct installation procedures for your waterproofing. Remember, it’s not just waterproofing, its water management.” He also emphasized that contractors “get a good layout of the tile selections on all the walls, whether it is only two or as many as nine – as is the case of a shower we are working on right now. Sometimes this process takes time, practice, patience, and wisdom.” Kerber stressed using mortar or thinset to install tile. “Absolutely no acrylic adhesives in a shower,” he said. And use “premium grouts and caulks. No acrylic caulk at the shower floor.”

4-tt-0715Another essential is proper installation of shower pans, Cox said. “Understand that a shower is a working assembly,” he explained. “Pre-slope is critical, folding your corners, wrapping your curbs, and putting the proper corners on where needed. We build ours with bricks or blocks for long term. Also know that any curb built with wood cannot have any fasteners on the top or inside that will lead to water intrusion.”

And above all, before even starting, “Educate the builder and framer on how it affects your labor when they do not pay attention to their quality control,” Cox concluded.

Tech Talk – June 2015


Hot Weather Tiling

2014/2015 NTCA Reference Manual

Since summer begins this month, we are literally taking a page (or two) from the 2014/2015 NTCA Reference Manual that relates to hot weather tiling. Materials require special handling to reduce the individual or combined effects of high temperature, low relative humidity, and high winds.

For instance, portland cement mortars and grouts can require additional water or latex for mixing, which can affect the bond and result in less open time, higher incidence of skinning over, plus dry-shrinkage cracking and improper curing.

In hot weather, organic adhesives produce creamier textures and increased workability that may lead to troweling too large an area before applying tile, as well as faster skinning over. Hot weather can sometimes reduce the viscosities of epoxies, making them more workable and at the same time accelerating the rate of cure, which can wreak havoc with mixing equipment and leave an epoxy film on the tile that’s very difficult to remove.

What follows are recommendations from pages 140-141 in the 2014/2015 NTCA Reference Manual that support well-performing installations by minimizing or controlling conditions that result from hot weather for projects that must be executed in hot weather conditions due to budgetary and scheduling demands.

Be sure to consider each project individually, since following one recommendation may not be sufficient to rule out problems. Evaluate exterior installation sites in advance, observing how many hours a day the installation will be exposed to direct sunlight and winds, and whether it’s feasible to construct a temporary shelter that can be moved as work progresses or if the work is better done at night or a cooler time of day.

In addition to temperature of materials, you must monitor temperatures of the job substrate. Hot substrates will exacerbate the hot weather effects of skinning over, reduced workability, premature drying and inability to form a strong bond for cementitious grouts and mortars. If you choose to cool a substrate with water, be sure to remove all excess water before applying the mortar.


Keep all materials in a shaded area and do not store materials in closed trucks or vans. This includes tiles, mixing liquid, setting and grout materials. If any material is warm to the touch it is suspect.

Don’t use tile that is hot to the touch. Cool your materials before proceeding. Some manufacturers market products specifically developed for hot weather conditions. They can be consulted concerning their products’ performance and recommendations under specific job conditions.


Portland cement

mortars and grouts

If using water, fill buckets and put them in a shaded area. If possible, use a combination of ice and water. Mixing water has the greatest effect per unit weight of any of the ingredients on the temperature of a cementitious mortar or grout. It has a specific heat* between four or five times that of cement or aggregate. Thus a change in water temperature of about 4 degrees Fahrenheit can effect a 1 degree Fahrenheit change on a mortar or grout. By using ice water, a more dramatic temperature change can be effected. The use of cold water will result in a decreased water demand of the mortar or grout when mixing. The working time of the mortar or grout will be increased and the workability will be improved. Using warm or hot water will cause an increase in water demand, consequent decrease in performance, a rapid loss of workability and decreased pot life. An analogous situation exists for latex additives. Except here, the addition of ice to the latex admixture is not recommended. A better recommendation would be placing the latex admixture containers into an ice chest filled with crushed ice. The containers can then be removed and the pre-cooled latex used as needed. Before applying dry-set or latex modified portland cement mortars to concrete substrates, dampen the concrete to cool it down slightly. Control how much mortar is troweled and combed before setting the tile. High temperatures and wind can combine or skin a mortar in several minutes. Check for mortar transfer to the tile backs often as the installation proceeds. Scrape off and discard skinned mortar and apply fresh material whenever skinning is noted. Never re-temper or add additional liquid to a mortar or grout that has lost its workability. Begin damp curing installations involving unmodified cementitious materials as soon as it is practical.

Rapid water loss can result in dry-shrinkage cracking that will compromise the integrity of the installation and ruin an otherwise acceptable grout application.


Organic adhesives

The viscosity of organic adhesives decreases with higher temperatures, making it easier to spread and trowel. Avoid the tendency to spread too large an area before tiling. In higher temperatures and in the presence of drafts, organic adhesives skin over rapidly, preventing good transfer of adhesive to the tile being installed. Check transfer often by removing a tile and observing the amount of adhesive on the tile back. Cooling the adhesive will help somewhat, but cooling in an ice bath is not recommended since the workability of the adhesive will be adversely effected by the increased viscosity.


Epoxy mortars and grouts

Every effort possible should be made to keep the temperature of the epoxy, tile and substrate below 90 degrees Fahrenheit. This may require working at night, the use of ice baths to cool the mixed epoxy and control its rate of setting or the application of damp blankets or towels to the installed tile before grouting in an effort to cool them. Do not overmix the epoxy mortars or grouts. Do not pre-moisten concrete substrates before applying epoxies. All manufacturers of those materials require that the components be intimately mixed for optimum performance. This can be observed as a homogeneous lump-free mix or by a thorough wetting of the aggregate or by uniform color. When any of these conditions is observed, STOP MIXING! Excessive mixing will accelerate the rate of cure still further from the heat generated by the mixing action.

When grouting, do not attempt to grout large areas of the tile field before cleanup. The result can be an extremely difficult-to-remove cured epoxy film on the tiles.


*Specific Heat – The ratio of the heat capacity of a substance to the heat capacity of water, or the quantity of heat required for a I degree temperature change in a unit weight of a material. Commonly expressed in Btu/lb/degree F or in Cal/g/degree F.

Coming this summer – the second annual issue of TileLetter TECH! Learn about hot topics in the current NTCA 2014/2015 Reference Manual and changes coming to the 2015/2016 edition.

Tech Talk – May 2015

TEC-sponsorMembranes for longevity and durability

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

Waterproofing and crack-isolation membranes can increase the longevity and durability of any application – from residential to extra-heavy commercial.


Understanding the functions and benefits of these products is critical to creating beautiful and long-lasting tile installations in demanding environments.

Why crack isolation?

As environmental conditions change, so do substrates. Changes in temperature and moisture can cause substrates to expand, contract and even crack. When the right installation materials are chosen, and they work as one system from subfloor to sealant, tile installations withstand movement and become longer-lasting spaces. Carefully selecting the right crack-isolation materials becomes even more critical when an installation will be subjected to heavy wheel loads and foot traffic, as is often the case in hospitals and car dealerships.

1TT-0515Crack-isolation products

Waterproofing and crack isolation-membranes address existing problems in the substrate, and help prevent future issues from affecting the tile installation. Waterproofing and crack-isolation membranes isolate existing substrate cracks to prevent in-plane cracks in the subfloor from telegraphing to tile. That way, movement beneath the installation surface will not affect the appearance of the tile or stone installation. These products’ waterproofing characteristics prevent moisture composition changes from affecting the tile installation.

Your crack-isolation product must be suited to the demands of its installation environment. For example, TEC® HydraFlex™ Waterproofing Crack Isolation is rated for extra-heavy commercial use and passed level 14 of the ASTM C627 Robinson Floor Test. This test measures the durability of the entire tile system. Level 14 of the Robinson Floor Test (the highest level achievable) requires a system to sustain a rotational rolling load with 300 pounds on each of three wheels for 30 minutes without cracking. That totals 450 rotations of 900 pounds of total load on the steel wheels.

2TT-0515Look for a product like TEC® HydraFlex™ that meets or exceeds ASTM C627 performance requirements of your installation.


Why waterproofing membranes?

If a stone or tile installation will be repeatedly exposed to moisture from an exterior source, you will need to make sure it is equipped to handle it. Wet installations – such as fountains, showers, pools and spas – must be prepared with a waterproofing membrane to adequately withstand the repeated exposure to moisture. Otherwise, they may be susceptible to deterioration and/or bond failures.

Waterproofing membrane products

Waterproofing membranes can form a smooth, monolithic, watertight surface over walls, floors and ceilings – just below the surface of the tile. Tile can then be bonded directly to the membrane. These products prevent substrate saturation, avoiding the development of any potential moisture-related problems. Look for membranes that exceed ANSI A118.10 Specifications for Waterproof Membranes.

3TT-0515Many products, like TEC® HydraFlex™ can be used for waterproofing or crack-isolation, if applied using the techniques specified by the manufacturer. Whether using a membrane for its crack-isolation or waterproofing capabilities, following the manufacturer’s instructions is imperative. The manufacturer will provide guidelines on suitable substrates and surface preparation products, and also suggest mortars that are compatible with the membrane. It is often best to use a mortar from the same manufacturer as the membrane.

4TT-0515With today’s demanding construction schedules, time is of the essence. You can use a waterproofing crack-isolation membrane without sacrificing efficiency. Some products can be applied over new concrete – as little as three days old – with a trowel, roller or spray, and are ready for tile installation in just two to three hours. These products make achieving long-lasting installations easy.

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®, ProSpec® and others – are available through an extensive network of distributors and dealers, as well as home improvement retailers. For more information, visit

5TT-0515TEC® and HydraFlex™ are trademarks of H.B. Fuller Construction Products Inc.

Tech Talk – April 2015

TEC-sponsorMoisture matters: how substrate moisture affects tile installations

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

tom_plaskota_webSubsurface moisture has always been a potential plague of floor-covering installations. However, for a variety of reasons, the consequences of subsurface moisture problems have only recently spread to tile installations. Learn about the effects of subsurface moisture on tile installations and how you can address it in the following article.

What happens

1-techtalk-0415In the past, tile installations were relatively safe from the effects of excessive moisture vapor emission rates (MVER). Moisture vapor emission occurs when water migrates from an area of high vapor pressure – such as damp concrete or wet soil – to an area of low vapor pressure – like a dry building interior. Once the moisture reaches an impermeable material, like vinyl, coatings and certain tile types, it may collect and condense, causing potential moisture damage. Excessive MVER can even discolor natural stone or tile and reduce the functionality of adhesives, grouts and membranes. It may also lead to unsightly efflorescence.

Why now

Today’s tile and installation practices have many benefits – including increased durability and efficiency. However, a combination of factors have made tiles more vulnerable to damage from excessive MVER.

2-techtalk-0415Historically, tile installations involved tile that was more porous, and in many cases the installer used unbonded cleavage membranes in conjunction with wire-reinforced mortar beds. These factors buffered the tile installations from moisture.

Tiles are now often bonded directly to concrete, which has been covered with a waterproof and anti-fracture membrane, making installations more convenient and successful, but less breathable.

Finally, and even more common in today’s fast-paced construction industry, schedules are more ambitious than ever, which means installations may take place before concrete moisture levels are completely stabilized.

3-techtalk-0415When to worry

Fortunately, with proper testing procedures, you can identify whether or not your installation will be affected by excessive MVER. The following are common tests that are used to check moisture content:

Test: ASTM F1869 – Calcium Chloride Test (Moisture Vapor Emission Rate)

Reading: Gives reading in pounds/1000 square feet/24 hours.

Test: ASTM F2170 – Relative Humidity Test

Reading: Gives reading in percentage of relative humidity (%RH) of the concrete slab.

4-techtalk-0415Interpreting test results and selecting products

With readings of < 3 pounds/1000 square feet/24 hours or < 75% RH, use any TEC® adhesives or mortars appropriate for your tile.

With readings of < 10 pounds/1000 square feet/24 hours or < 88% RH, use a TEC® latex-modified thin set to install tile.

With readings of up to 12 pounds/1000 square feet or 90% RH, use TEC® HydraFlex™ as a waterproofing or anti-fracture membrane or TEC® Roll-On Crack Isolation Membrane prior to installing tile and stone.

With readings up to 25 pounds/1000 square feet or < 100% RH use TEC® The LiquiDAM™ to reduce the floor to acceptable levels of < 3 pounds/1000 square feet. Then, prime with TEC® Multipurpose Primer and install with a TEC® latex-modified thin set.

Note that the moisture test results indicate the moisture condition of the slab only at the time of the test. Although concrete often absorbs water from the ground, it can also absorb water vapor from the air in humid conditions. Moreover, concrete releases more vapor when the air humidity is low. These fluctuations in environmental conditions can affect relative humidity levels, and tests should be repeated over time.

Another moisture problem is hydrostatic pressure. Hydrostatic pressure occurs from liquid water from a source – such as a high water table, broken pipe or sprinklers – that may create a negative hydrostatic pressure issue. This condition should be addressed prior to installing tile or any other flooring.

Both efficiency and frugality are valued during stonework and tile installations. Although addressing moisture – from a variety of sources – requires an initial expenditure of time and money, doing so can ultimately save you and your client from frustrating and costly callbacks.

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® 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 The LiquiDAM® are trademarks of H.B. Fuller Construction Products Inc. 

Tech Talk – March 2015

TEC-sponsorCustomers warm to electric-heated floors; WiFi thermostats allow remote-control energy efficiency via smartphone or web

By Lesley Goddin

Years ago, if your customer wanted a heated floor, they needed to invest in a complex hydronic system, with copper water-bearing tubes running beneath the floor and a boiler to heat the water and thus the floor.

Over the last few decades, ELECTRIC floor warming systems have been developed by a number of manufacturers. These systems – which utilize heated electrical wire or cable in a loose configuration, a mesh mat, wire snapped into a lightweight backer or uncoupling mat, or even carbon strips embedded in extremely thin PET film – all provide floor warming under tile and stone that is quick, relatively easy to install, and affordable.

1-tech-nuheatSmartphone control via WiFi thermostats

The latest innovation in electric floor warming (or in some cases, full-house heating) systems is WiFi controls, which enable users to control their heating systems, temperature, schedule and energy consumption remotely through their smart phones or other electronic device. Nuheat ( debuted this technology with its Nuheat Signature Programmable WiFi Thermostat. And this January at KBIS during Design & Construction Week, Warmup ( unveiled a WiFi system as well – the 4iE Smart WiFi Thermostat.

Peter Thomson, vice president of sales for Nuheat was at TISE West. He noted that the Signature WiFi app can control up to 16 thermostats on one app, and it’s very zonable. “People are reclaiming their basements with supplemental heat sources,” he said.

Martin Brookes, of NTCA Five Star Contractor Heritage Marble & Tile in Mill Valley, Calif., installs radiant heat in about 60% of Bay Area homes, using the Nuheat system. “We really like the WiFi -enabled programmable thermostat. Living in the Bay Area, the clients are tech savvy and want things they can control with an app from their smart phone.”

2-TECH-warmupAt Warmup, Regis Verliefde, CEO, said the 4iE Smart WiFi Thermostat offers multi-zone and multi-room management as well, in line with Warmup’s goal to provide heating for the whole house. In addition to monitoring the energy consumption, Warmup’s device makes active recommendations to optimize energy use. All this can be directly managed from smartphones and tablets on the MyWarmup portal. (

“We are excited to attend KBIS to show off our latest innovation,” said Verliefde. “Warmup is so much more than luxury in the bathroom. It is a heating solution on par with any other one today, but healthier, more silent and maintenance free.”

3-tech-cmxHeating film; multi-function mats hold cables

Other interesting developments in electric floor warming have taken place over the years. Geo Dream ( encapsulates carbon strips in an extremely thin PET heat film for a system that is zonable, affordable and durable, and heats the house with far infrared waves.

In the last few years, flexible backers to configure wires or cables have emerged, such as RPM mats, which sprang onto the scene in 2006. These mats are studded to accept floor warming cables in any configuration. A new RPM-V1 design has vented studs, that accelerate the drying of the adhesive beneath the mat.

4-tech-schluterLaunched a few years ago is Schluter’s DITRA-HEAT, designed to snap heating cables into a studded uncoupling mat. This mat/membrane provides crack suppression, waterproofing, vapor management and helps to distribute loads as well.

“We just did our first DITRA-HEAT project and liked the flexibility of the system,” said Brookes. “Rather than having to wait for a custom mat, we were able to get the radiant heat we needed off the shelf. “

Italian-made PRODESO HEAT from Progress Profiles features a patented blue studded mat that can be installed as an uncoupling, crack isolating membrane. The heating cables are installed according to the needs of the project. Tiling can begin immediately. The entire Prodeso Heat system is less than 1/4” thick.

5-tech-prodesoCautions and considerations

When working with radiant heating systems, technical service is as important as technology to John Cox, NTCA past president and owner of NTCA Five Star Contactor Cox Tile in San Antonio, Texas.

“The most critical item in my book is customer service. When I call Nuheat, I get answers. They have a staff that has been well trained and educated.

“Selling radiant heating has added additional income to our bottom line and added to the distinction of Cox Tile not being your average tile contractor,” he said. “We have developed a niche as being the expert in our area in Radiant Heating. When architects’ specs say Cox Radiant Heating, we know we have made an impact.”

6-tech-suntouchRicky Cox, of NTCA Five Star Contractors Memphis Tile in Memphis, Tenn., said, “We use Nuheat for the ease of installation, superb customer service, and a long working relationship that has kept us going back for more.  I have installed every system out there and Nuheat blows them all away. The wires are embedded between two layers of fabric that are easily thinset to the substrate.  Other systems are hard to ‘flip and roll’ and hard to figure out.”

Contractors and consultants offer a range of warnings and recommendations when working with electric floor warming.

“Always have the system inspected by a state inspector,” said Joe Kerber, owner of NTCA Five Star Contractor Kerber Tile, Marble & Stone in Shakopee, Minn.

“Always test the cable and sensor for resistance and continuity, before, during and after the installation,” he said.” Be careful when walking on and troweling over the cable so not to crush it or nick it with a trowel. A nick could cause the GFCI to trip when heated. Remember the wires are very fine. The sensor is very fragile so do not step on it.

“There are two types of cable,” Kerber continued. “Most are the double-wire cable that goes out from the box and ends at the end of the cable in the floor area. SunTouch Warm Wire and Nuheat cables are example of these. The other is the single wire that has to return to the original box. The Nuheat mat and Flextherm cables are examples of these. The double-wire cables are easier to install because you don’t have to get the other end back to the box. However, the single wire cables are much easier to repair.”

Jan Hohn of NTCA Five Star Contractor Hohn & Hohn, Inc., in neighboring St. Paul, Minn., added, “I usually prefer to do wires or cables instead of a mat. With the wires, you can really customize the space that you are heating because you can run the wires where you want them, putting them closer together for more heat in a specific area and/or farther apart where there is less foot traffic. Another reason I like the wires is because I float my floors with mud so the wires are buried in the mud bed, which allows for a more consistent floor heat (more mass to heat up, but once it is heated it holds the heat longer and more evenly).”

Hohn cautioned against placing wires or mats under any cabinetry, toilets, or other plumbing fixtures.  “Some systems can be used in showers, but not all, so it is important to determine if the system you want to use can be used in the shower,” she said.

“Recently, it has been recommended to install two floor sensors with one system,” she added. “If the first sensor stops functioning, you can hook up the second sensor without tearing the floor up. It is cheap insurance.”

Rich Goldberg of Avon, Conn.-based Professional Consultants International, LLC (PROCON), noted that “Radiant heat naturally increases cycles of expansion and contraction of a tile assembly, making proper installation of movement joints critical. Butted grout joints with no movement joints in high-end residential stone installations are also a common problem, causing chipping and crushing along stone edges at butted joints.”

Often radiant heat is used to “accelerate” the curing, he said, but this can create problems with premature drying, and expansion stress on the thinset before the bond strengthens. Rapid drying of underlying wood framing in new construction and cement backers can telegraph movement to the tile assembly and result in cracking.

He also warns that cable trays can create dividers in mortar beds that encapsulate the system and crack the mortar, and eventually the tile. They can also prevent mortar adhesion, so PROCON favors systems that “employ the heating cables within a reinforcing mesh so that the system can be properly encapsulated by mortar top and bottom, and the reinforcing distributes any heating/drying/expansion/contraction stress evenly in the mortar bed.



Tech Talk – February 2015

TEC-sponsorAchieving successful natural stone installations


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

Although advances in manufacturing have expanded the possibilities of man-made tile, natural stone remains highly sought after for both residential and commercial installations. A truly timeless building material – among the world’s oldest – natural stone offers a look that cannot be perfectly emulated by a manufacturing process. By guiding your clients to the right stone and setting it with the most appropriate materials, you will achieve beautiful and durable installations.

Natural stone, as its name suggests, is quarried from the earth. Because of this, it does not offer the perfectly consistent appearance of man-made tiles. Encourage your clients to view several sample tiles from the same lot before making their selection. That way, they can get a sense of how their tile’s appearance may vary.

This diverse material is available in a variety of finishes, and the finish your client selects should be dictated by the project’s environment. Polished stones, for example, are very reflective and may be more sensitive to scratching than other tile types. Honed, flamed/thermal and water-jet finishes are rougher, often obtaining higher slip-resistance ratings than polished finishes. Direct your clients toward higher slip-resistant finishes for floor installations – especially in wet areas.

0215-tech-1If your client’s installation will be on an exterior surface, be sure that the tile they select can withstand freeze/thaw conditions. Specific ASTM tests will verify how well a material may hold up in extreme conditions. Suppliers should be able to provide guidance and technical data to support the recommendations.

Similarly, installations in wet environments – like a shower or pool – require particular attention to stone selection. Many green marbles warp when exposed to water, even from water-based adhesives. These moisture-sensitive stones should not be used in wet environments and should be installed with 100% solid epoxy mortar. Take absorption into account during your selection. The higher the amount of water absorption, the greater the likelihood of damage caused by moisture.

Both performance and aesthetics will determine the setting materials to accompany the natural stone you and your client select. Some natural stones – including light-colored marbles, limestone and onyx – can experience staining or darkening from grey mortars. It is best to specify white mortars for these applications.

0215-tech-2Regardless of color, natural stone requires a minimum of 95% mortar coverage. No voids in the adhesive can exceed 2 square inches and no voids should exist within 2” of tile corners. To achieve consistent coverage, use a larger U-notch or square trowel than you would for similarly-sized ceramic tile. You can also back-butter the natural stone to help ensure 95 to 100% coverage.

Grout is the final ingredient for a successful natural stone application. Particles in sanded grout may scratch limestone, travertine, marble and onyx. If using one of these softer natural stone tiles or polished stone, specify unsanded grout and use grout joints of 1/8” or narrower. Be sure that the grout selected – sanded or unsanded – will not stain the natural stone. Using a grout color similar to that of the natural stone tile will help minimize this risk, as will applying a sealer or grout release prior to grouting. Use the same sealer prior to grouting that you plan to use afterwards.

0215-tech-3To make cleanup easier, consider using a grout bag to grout natural stone installations, particularly with textured tiles. Mix small batches of grout, scoop them into the bag, and squeeze grout from the bag directly into joints. Use a grout float to pack each joint, and then scrape away the excess. If the tile is less textured, use a float to apply the grout directly into the joints.

If you have any questions about the aesthetic or performance compatibility of your tile and setting materials, create a sample board using your client’s natural stone with the mortar and grout you’ve selected. This process will help you determine whether staining is prominent and how the grout and tile look together. Share it with your client to ensure that they will be happy with the final installation.


Tech Talk – January 2015

TEC-sponsorFollow directions, not intuition, for best results with today’s mortars

Lesley beach picBy Lesley Goddin

“Mortar products today are so much better than they were years ago,” said new NTCA president and NTCA Technical Committee chairman James Woelfel, of Artcraft Granite, Marble and Tile Co., from Mesa, Ariz. “That’s why you don’t see as many failures as you ‘should’ see, if you were using mortars from 30 years ago.

“Mortars today are so fantastic,” Woelfel added. “Today, we have flowable/thixotropic and non-sag mortars. They are phenomenal – but they are a double-edged sword,” he said, stressing that if they aren’t used properly, the installation will fail spectacularly.

Woelfel – together with several technical representatives from manufacturers who have collaborated on authoring and editing the mortar section of the NTCA Reference Manual– have some important recommendations for getting the best results from today’s mortars.

Use the right material for the job

An obvious – but oft-ignored recommendation – is to use the proper mortar for the proper tile, Woelfel said. “The more expensive mortar doesn’t cost you more than $.05-$.07 a foot or maybe all the way up to $.15 more a foot,” he explained. “By using the right mortar, you are really buying yourself insurance. Since mortar is the least expensive part of a tile installation, if you are depending on the savings on that mortar to make you a profit, you are going down the wrong road. And if you are improperly using an inexpensive mortar, and building it up, are you really saving money in both material and time?”

Water ratio – follow directions, not intuition!

Second, be sure to mix the mortar the way the manufacturer recommends.

“The mortars being built today are very complex formulations and a lot of ingredients in these formulas require the proper amount of water,” said Leigh Hightower, technical services manager for MAPEI. “Contractors are used to mixing mortars to feel, but today’s mortars have a lot of materials in them that don’t wet out very quickly. If the mortar looks too thick as it is being mixed, and more water is added when it is mixed up, when it does go into solution, it is too thin. Mortars today need to be mixed with a measured amount of water according to instruction and not feel,” he said.

Tom Plaskota, with TEC/H.B. Fuller Construction Products, added, “job site conditions can affect installation and temperature-range limitations are pushed to the limit with the pace of fast track construction these days. This occurs on both the low and high ends of the temperature range, depending on what part of the country you are in and what time of year it is.”

Woelfel cited some of his experiences setting tile in the desert climate of Arizona. He said it’s easy to “overwater thinset in dry climates; there’s more chance to shrink here as it dries. Thin-set mortar sets up faster in Arizona and New Mexico – in fact, in Arizona this June, we set a record for 2% humidity.”

Woelfel said this is a problem because even if one is following strict manufacturer recommendations, those recommendations generally aren’t based on use in extreme conditions. “[Mortar is] tested at 75 degrees and 55% humidity,” Woelfel said. The tendency for mortars to skin over too fast in low-humidity settings is especially crucial when working with large-format, or large thin porcelain tile. Once that happens, there’s no bond.

Woelfel favors the development of more mortars that accommodate the particular conditions contractors encounter around the country – high humidity, or super-low humidity – so contractors have a reasonable amount of open time to set the tile.

“Most people in my area are subcontractors,” Woelfel said. “They are putting tile in as fast as humanly possible, which means they will trowel out 40’ to 50’ of thinset and just drop the tile. They don’t key it in, and it stays on top of the trowel marks. When it’s pulled up, it’s almost clean. There are a lot of failures in Phoenix due to mortar skinning over,” Woelfel said.

Bubbles weaken bonds

Woelfel also cautions contractors to take time with mortars and let them slake. “You need to mix with a low rpm mixer at the proper speed that the manufacturer recommends,” he said. “Otherwise, you can get air bubbles, which makes the mortar set up faster and become weaker. You have to let it rest and coalesce.”

A new name and clearer definition

Large and heavy tile (LHT) mortar, has gone through a transformation – and not just in name only – from the previous “medium-bed” mortar moniker. “Medium-bed” mortar was coined to refer to a MATERIAL – a type of mortar, not a METHOD of tile setting, according to MAPEI’s Hightower. But over time, it became misunderstood and mis-specified in the A&D community as a method of smoothing out imperfections in the substrate in lieu of the proper practice of using a self-leveling underlayment. Contractors got caught in the middle, Hightower said, when they started to be expected to smooth out substrate irregularities with medium-bed mortar, used up to 3/4” in thickness instead of going the proper route of using a self-leveling underlayment. The industry responded to this conundrum by changing the confusing name and limiting the thickness recommended to 1/2” to avoid misuse of this important material. For more information, check out this month’s “By the Book” section in which ProSpec’s Beverly Andrews talks about new parameters for use of LHT mortars or what we formerly called “medium-bed” mortar.

Up-and-coming products for LTPT

LHT mortar segues into mortars many manufacturers are developing specifically for large-unit thin porcelain tiles. These mortars are tied in closely with the standards discussions about large thin porcelain tile (LTPT). As these mortars are in development, contractors are offering feedback on realistic performance criteria. Some manufacturers required 1/64” lippage tolerance, Woelfel said – something unattainable with bigger thin tile. This is where the NTCA Technical Committee, TCNA and other industry entities are putting their heads together to formulate products and methods that will meet the needs of the contractor with excellent performance while the large thin porcelain tile itself is under close scrutiny in terms of performance characteristics and installation recommendations. Stay tuned to TileLetter for ongoing news about LHT mortars for LTPT throughout the year!

Tech Talk – December 2014

TEC-sponsorCold weather tiling

By Lesley Goddin the NTCA Reference Manual

December means cold weather for most of our 50 states, so this month’s Tech Talk literally takes a page out of the NTCA Reference Manual to discuss the particulars and cautions that surround setting tile in cold weather.

The NTCA Reference Manual is an essential industry guide that references real-world, in-the-field situations, in most cases with a cause-cure-prevention format. It also contains letters that can be customized to various parties in the project to legally communicate problems to keep tile contractors harmless in a dispute. This indispensable publication is now available to the entire industry. Visit or click on the “store” link at NTCA’s website, and select books and periodicals to get your copy today.

Following are the recommendations for successful cold weather tiling:


The professional installation of tile in cold weather presents a number of problems. The best results will be obtained when the environment and the products are about room temperature. Each bonding material will require specific precautions.

Tile bonding and grouting materials must not be applied to surfaces that contain frost. Tile must not be installed in areas where the substrate is not maintained above 50° F (10 C) or where the substrate is above 100° F (38 C). Temperature of the substrate shall be 60° F (16 C) and rising for application of epoxy and furan unless otherwise specifically authorized by its manufacturer. Maintain epoxy and furan at a stable temperature between 60° F (16 C) and 90° F (32 C) during the curing period.

Industry specifications do not recommend setting tile below 50° F. If work below that temperature is unavoidable, common sense procedures and precautions should be observed. Be aware that it is the temperature of the tile products, bonding materials and substrate which count – not just the air temperature of the room.

Cold weather slows cement hydration (curing)

It is recognized that cold weather slows the strengthening of cement mortars and grouts and allowances must be made for the resulting risks.

As the temperature drops from 50° F to 35° F, the strengthening of cement slows concurrently, until at 35° F it almost ceases. When these conditions occur, additional time must be allowed for the cement bonding materials to sufficiently harden before traffic is allowed. If the water in fresh cement is allowed to freeze solid, particularly near the surface, the small ice crystals expand, separate the sand and cement, and destroy the strength of the mortar, resulting in a bond failure.

2-TT-1214In cold temperatures, grouting done before the bonding material is strong enough to accept traffic, will cause movement of the tile resulting in irreparable bond failure. When the temperature is below 50° F, grouting should be done immediately after the tile is set or wait at least two to three days. No traffic should be allowed during this period. When continuing a job, special precautions must be taken to keep all traffic off the tile that was set the previous day.

When using blower heaters to protect tile from freezing, caution must be taken to avoid rapidly drying out the tiled area directly in front of the heaters. There is a risk of drying out the air in heated areas preventing proper curing of mortar and grout. It is advisable to damp cure under these conditions.

The use of electric heat is preferable to oil or gas-fired temporary heaters that can cause chalking carbonation and weakening of fresh mortar or grout.

Cover ungrouted surfaces during the initial setting period for protection against drafts and freezing temperatures. Fast-setting mortars, although susceptible to freeze damage, may reduce curing time if the manufacturer’s recommendations are followed.

Epoxies and urethanes

Epoxies require special cold weather precautions. The most likely conditions to occur because of cold temperatures are:

1. A thick stiff mix.

2. Difficult application.

3. A very slow cure and strength gain.

For these reasons, most epoxy products are recommended for use between 70° F and 80° F. Low temperatures can cause epoxies to become so stiff they are unworkable and curing time is extended beyond practical limits. Epoxies should be stored at room temperatures at least 48 hours before mixing. Most epoxy problems result from improper and insufficient mixing.

3-TT-1214Cold weather tiling tips

Nadine Edelstein, winner of a 2010 TileLetter Tile Design Award for the slate strip mosaic in the Maury Island residence outdoor entryway and a 2013 Coverings Installation Design Residential Stone Design Award for the Dragonflower Vine raised-bed garden pathway in Seattle, Wash. Edelstein installed both winning projects during the during the cold northwest winter.

Conditions for the Maury Island project included temperatures in the 30s and wind whipping through the space. The crew bundled up to stay warm and took measures to keep the concrete substrate and curing mortar above 40 degrees. Edelstein said she “used electric blankets over the set tiles layered over with insulating blankets and tarps to keep the heat in. The next day we used the blankets to preheat the areas we intended to set.”

For her 2013 Dragonflower Vine project, elaborate measures included a framed enclosure built over the entire 500+-sq.-ft. garden. “This was covered with heavy-duty tarps that were secured with full five-gallon buckets hanging off the sides!” Edelstein said. “This kept us dry and provided enough ventilation so that we could use a 100,000 BTU propane heater, which kept the chill off of us while we worked. We then employed the same electric blanket technique to help our mortar cure.”

A note of caution from industry expert and ceramic consultant Dave Gobis, CTC – be sure to provide plenty of ventilation – as Edelstein did – when tenting a project. “A tented installation or the cement could kill you from either carbon monoxide or dioxide. Be sure you have plenty of air moving through the enclosure.”

Tech Talk – November 2014

TEC-sponsorA quick thought on labor and large-format tile

hunterBy Lewis Hunter, estimator

I can’t tell you how many times I have been in a conversation with the estimator or project manager of a general contractor (GC) who has wanted me to give them a revised price for 12” × 24” tiles in lieu of 12” × 12” tiles. And when I return the requested price, without fail, they are shocked to see that the price has dramatically increased.  They often argue that the prices of both tiles are relatively the same.  And what’s even more astounding to them, is that I agree.

1-TT-1114It then has to be explained that the increase in cost was due to the labor, increased floor prep, and setting materials. The GC’s estimator further argues that the 12” × 24” piece (2 sq. ft.) of tile is two times the size of the 12” × 12” (1 sq. ft.). This is where it needs to be further explained that with the installation of large-body tiles (typically anything larger than a 12” × 12”) the issue of lippage is more pronounced. Also, the tolerance associated with any sloping in the floor has to be offset. Basically, you have to make the subfloor flatter. The hard-tile estimator now has to account for a thicker mortar. Medium-bed mortar will have to be substituted for thin-set mortar. Consequently medium-bed mortar is more expensive, and the coverage is less than that of thinset. Likewise, labor is increased because the installer now has to massage each piece of tile to make sure it’s level with each adjoining piece. This affects the productivity, which can be reduced by half in some instances. All of these components combined increases the overall price.

2-TT-1114Now, as tile estimators, wouldn’t our lives be so much easier if the end user’s expectations included the above information?


Lewis M. Hunter Jr. was a commercial hard tile estimator for several years in Raleigh, NC. He now serves as the estimating manager for the top residential flooring company in Northern Virginia. Visit or contact him at [email protected] for more information.

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