DCOF on a pool deck


I’m designing a home and need to pick a tile for a residential pool deck. Are there standards for using slip-resistant tiles in areas like this, and if so, what are they?


Thank you for contacting the NTCA, The measurements for slip-resistance are referred to as COF (Coefficient of Friction) and DCOF (Dynamic Coefficient of Friction). COF is the measurement of a tiles static frictional resistance, closely related to traction and slipperiness. DCOF is a measurement of dynamic friction, which is the frictional resistance one pushes against when already in motion.

Regarding the question of whether there is a specification or guidance for DCOF on a pool deck.  There is no specification or standard for slip resistance/DCOF/COF on a pool deck.  The reason is that each has its own unique design and use.  As such, it is up to the good communications process between the architect/specifier, owner, distributor, and installer to discuss and determine the best tile (type, glaze, traction, size, number of grout joints, etc.) for the installation being considered.

In addition, the tile and setting materials, membranes, expansion and movement joints, and other factors must all be carefully considered and approved or engineered for the application.

The NTCA Technical Team

Attracting young artisans to the craft of tile

In our March issue, NTCA Executive Director Bart Bettiga interviewed Lee Callewaert of Dragonfly Tile & Stone Works in Grafton, Wis., and Joshua Nordstrom from Tierra Tile in Homer, Alaska, for his One-to-One story. 

Amidst all the wisdom shared by these stellar artisans was some advice on recruiting young people into the trade, and how to emphasize the artistic aspects of tile setting to attract creative young people interested in making enduring art with their work. Here are Callewaert’s and Nordstrom’s suggestions and observations. – Lesley Goddin, Editor

Bettiga: What advice would you give to small business owners on how to recruit young people into the trade and encourage them to come work for them? On that same note, you are both artists. How can we reach out to people with an artistic background to make them aware of the opportunities in our industry and what tools should we develop to tell that story?

Callewaert: I think it’s about your mindset. I think of our trade as an artisan craft and project that in my work and in my discussions with customers, suppliers, trade partners, fellow installers, and potential employees. We need to lose the “Tile Guy” perception/image and regain the historic reputation as artisans and craftspeople. The more we project the professionalism of our craft and its place as an artisan trade, the more we will attract young workers. And I see every well-executed and detail-oriented installation as “art.” It doesn’t need to be the large artistic mosaic or cut stone features. I teach my apprentices the importance of every detail and the visual impact it has on any installation. 

When we talk about the skills and attributes we are looking for in an employee, artistic sensibility and background are always highlighted as preferred. Young people don’t just want “work.” They want to feel like they are part of something important and stimulating. Our employees have come to us through various channels but usually because they have heard about the quality of our work and that we do “cool stuff.” One simply responded to an ad after browsing our website. He has artistic skills and was drawn to that aspect of our work. Another heard about us from a trade partner we have worked with. She started her college career in art studies but wasn’t sure where she wanted to take that. This trade partner recognized a potential fit, sent her to our website, and introduced her to us. But in all cases, none were just looking for a “job.” They were attracted because of our reputation and the artistic nature of our work, and yes, the “cool factor.” 

Maybe we need a campaign to “Make Tile Work Cool Again?” We will be adding this hashtag to our social media posts: #youngartisticskillsneededinthetrades!

We should continue to reach out to high schools, trade schools, art schools, and other organizations where young people are considering their career options. Maybe there could be a presentation template that any of us could use to present to these audiences. Maybe some tips on how to approach them. Incentivizing our younger employees to conduct these orientations or work the job fairs is one idea. They are fresh and new and can relate to the audience. It’s the time and organization that might make this more difficult. 

Nordstrom: I have little advice to offer of how small businesses can recruit young people into the trade to come and work for them. I can say with the qualified knowledge of being a tile installer, this is a trade that can be taken with you wherever you choose to be in life and not have a problem finding work. You can make as much or even more in some cases than your college-bound friends, have the freedom of choosing your own schedule, who to work for, and not have the burden of paying off a college loan. 

With or without an artistic background, there are ample opportunities for every job to add something creative. I find that people are always willing to pay a little extra for something that they might not know exists especially if you can make it personal to them and their tastes. We all work every day with a broad palette of textures and colors. You can experiment with a variety of colors or just stay with one and accentuate the grout lines for a tone-on-tone effect. You need to be willing to step out of the square grid of grout lines to push your limits and challenge yourself. 

It’s also useful to be observant of current trends and colors, what kinds of things your client seems to collect or be into, their color schemes, and be aware of what the water-jet guys are producing. People will pay more for something that they can have a part of creating, knowing that it was hand made by an artist. If you are capable of cutting a radius, then the sky is the limit. I found myself starting out cutting stained glass designs. These come already patterned out and just need to be blown up to size. They come in many different varieties. 

Adding artistry into the skill set of being a tile setter will set you apart from your competitors and further your chances of being a successful tile contractor.

Should you soak encaustic tile?


I am a member and need a few questions answered about an encaustic cement tile installation. I only have about 35 sq. ft. installed, but the homeowner on a job insists I should have soaked the tiles prior to installation to create a proper bond. I am trying to check with the manufacturer for their recommendations but they are in the UK and I’ve had a delay due to time zone differences. The setting material manufacturer said that since the back of the tile was wet, they are confident it would be well adhered. Are there any standards for installing encaustic cement tiles? 


I don’t believe these tiles need to be soaked before installation. The best way to check bond to the substrate is to remove one to see how well it was adhered. Since the dealer does not have a comprehensive installation recommendation and this tile does not meet the ANSI A137.1 Standard Specification for Ceramic Tile, the decision on whether or not to soak the tiles prior to installation should be reviewed with the tile and setting material manufacturers. Request written installation instructions from each manufacturer along with their warranty on this project.

What industry document supports installing stone over tile in a wet area?


I was curious if you could direct me to an industry document supporting the proper technique for installing Jerusalem limestone in a shower wall (stone over tile). The stone is 3/4” thick, and approximately 4’ x 5’. I don’t know the weight per foot. Can this be direct bonded or would it need mechanical fasteners? I’m looking for a document that would support one or the other.


When it comes to a large stone slab like this I need to direct you to the Natural Stone Institute (NSI) (naturalstoneinstitute.org). When 3/4” stone exceeds 24” on a side, it becomes outside the realm of typical tile installation and the NSI are the persons that best know how to handle this material. Their Dimension Stone Design Manual may address installing a slab over existing tile in a wet area, but I am not certain.

Adding mechanical fasteners may likely penetrate the waterproofing membrane, which can/will create problems with the system’s water management integrity. If the stone is not direct bonded with 95% coverage over the existing tile layer or membrane, any voids behind the stone may trap moisture, bleed through, and stain the stone (possibly permanently). NSI can speak to you about the suitability of limestone in a wet area. I am guessing this is a project you are involved with as the setting material manufacturer. You might want to advise the client that limestone can be a tricky stone for a wet area.

There are gauged porcelain tile panels (GPTP) that can be applied in a tile-over-tile, direct-bond situation without additional fasteners. You may want to suggest your client considers GPTP as an alternative. I can put you in contact with GPTP manufacturers/distributors if needed.

In the meantime, I am sure you know these things – but here are a few reminders for any tile-over-tile installations in a shower situation:

  • Ensure the existing tile installation/substrate is suitably well bonded, plumb, flat, etc., to support the new installation
  • Ensure the waterproofing membrane is intact or a new membrane is applied and connected to the pan
  • Take a look at TCNA Handbook methods TR418 and TR 420 for Shower Receptor Renovation details
  • Follow EJ-171 Movement Joint Guidelines

– Mark Heinlein, NTCA Technical Director


Here are a few more items for your consideration.

That slab of Jerusalem limestone would weigh approximately 205 lbs. dry and would increase when wet.

There are three classifications for limestone under ASTM C568 as follows:

  • Class I (low density) 7.5% to 12%
  • Class II (medium density) 3% to 7.5%
  • Class III (high density) up to 3%

The finish of the stone (normally honed) and the density of the stone will determine its porosity.

When it is installed in a wet environment (follow Mark’s advice on the installation), it should (must) be sealed using a breathable penetrating sealer per the manufacturer’s recommendations on the number of coats and dry time. Jerusalem limestone will require ongoing maintenance to keep it sealed and more easily cleaned. 

– Scott Carothers, Director of Certification and Training, CTEF

Working with face and mesh mount sheet mosaics

It is not breaking news that tiles are made in all colors and shapes and sizes and thicknesses and materials. They each have their own beauty, and tiles of all types and sizes are regularly mixed together to create stunning installations with purpose and function that stand the test of time when properly engineered, specified, designed and installed.

Installation spotted at a public market in Seattle, Wash. 

This article focuses on installing mosaic tiles that have been pre-assembled into a pattern on sheets of mesh, paper or plastic.  But first, a little information about mosaics. 

What are mosaics?

The American National Standard Specification for Ceramic Tile (ANSI A137.1) defines ceramic mosaic tile as: Tile, usually 1/4” to 3/8” thick, and having a facial area of less than 9 square inches. Such tiles are typically mounted in sheets or strips with other mosaic tiles.

Where do mosaics come from?

Many tile manufacturers create mosaic tiles for one-of-a-kind and general pattern installations. The tile industry has a host of notable tile artists who create one-of-a-kind hand-crafted mosaics. By their nature, many tile installers are craftspersons with artistic skills. The Tile Trade Artisans Guild Facebook group is dedicated to encouraging artistry in the trade. Visit it at www.facebook.com/groups/tiletradeartisansguild

How are mosaics mounted?

Artisan created and installed one-of-a-kind mosaic. Photo courtesy of Dragonfly Tile & Stone.

Mosaics can be edge-mounted. Flexible glue is applied to the tile edges, leaving the back of the tile open for full contact with the bond coat. Paper or plastic can be applied to the face of the tile leaving the back open for full contact with the bond coat.

It is important to note that when mesh is applied to the back of the tiles it will become an integral and permanent part of the tile installation. There must be sufficient openings in the mesh netting to allow for adequate, direct contact of the bond coat to the back of the tile. If mesh mount tiles are to be installed in an exterior, wet or submerged installation, the mesh must be suitable for exposure to water.

A common concern with installers is how straight or crooked the mounted mosaics are. It can be tedious work to straighten crooked tiles that are stuck to a sheet. For readers interested in acceptable variations of mosaics mounted to a sheet, open up your copy of ANSI A137.1, study Table 6 and read section 9.5 Test Method For Mounting Variations.

How are mesh and face mount mosaics installed?

First, examine your substrate. Is it flat? If not, stop the installation and start the conversations that lead to making the substrate flat. Is there a membrane in place? This will affect cure time, especially for glass mosaics and plastic face-mounted mosaics.

Proper bedding procedures: For an outstanding description on how to properly bed mosaic tiles (set into mortar), pull out your 2019/2020 NTCA Reference Manual and read pages 108 – 110.

Mesh and face mount mosaic installation instructions:

  1. Check the substrate for flatness.
  2. If the substrate is not flat, make it flat. (Attend an NTCA Regional Training program to learn the skills, tools, and materials to do this.)
  3. Check the area to be tiled for squareness.
  4. Calculate the best, most defensible layout and consider the primary focal point and use. (Attend NTCA virtual and in-person workshops to learn how to do this. For more information, read the Training & Education story in this issue.)
  5. Apply a grid system for the layout to follow.
  6. Clean the substrate.
  7. Dampen dry substrates.
  8. Mix the mortar, following manufacturer instructions.
  9. Key the mortar into the substrate with the flat side of the trowel.
  10. Use the gauged side of the trowel to apply more mortar.  Hold the trowel at a consistent 45-degree angle and trowel the mortar into straight ridges.
  11. Prime the trowel by applying a ridge of mortar along the length of the flat side of the trowel.
  12. Hold the primed trowel at a shallow angle then drag it, flattening the ridges to create a consistent, bond coat layer consistently 3/32” to 3/16” thick (approximately).
  13. Set the tile into the mortar.
  14. Use a solid, flat trowel, float, or similar tool to embed the tile into the freshly troweled bond coat layer. Press well enough to ensure a minimum bond coat of 80% (dry areas) and 95% (wet areas) without forcing excess mortar into the grout joints. Bond coat coverage percentages are for each individual mosaic tile. Pull some tile to check for coverage. Change your trowel size if needed. Practice your technique.

Mesh mount-specific instructions:

  1. After setting the tile and making sure bond coat coverage is achieved, align the tiles to ensure there are no sheet lines.
  2. Insert the long, clean edge of a straight, flat trowel into the joints and use it to align the mosaics within the sheet and align the joints from sheet to sheet. A soft grout float can also be used to shift the tile.
  3. Stagger sheets as you install them to blend the grout joints from sheet to sheet.
  4. Cut squares or rectangles from sheets to overlap sheets as you install them, blending grout joints from sheet to sheet.
  5. Step back from your work and take photos of small sections as you set them. Sheet lines can be much more visible in a photo than when you are focused up close. Examining your work in this way as you go allows you to see sheet lines that you couldn’t while setting and make adjustments while they are freshly set.
  6. Use hard shims, spacers, wedges, or apply tape to the surface to hold tiles in place while they cure.
  7. After curing, clean squeeze-through mortar before grouting and applying sealant at movement and expansion joints and changes in plane.

Paper face-specific instructions:

  1. After setting the tile and making sure bond coat coverage is achieved, align the tiles to ensure there are no sheet lines.
  2. Stagger sheets as you install them to blend the grout joints from sheet to sheet.
  3. Cut squares or rectangles from sheets to overlap sheets as you install them to blend grout joints from sheet to sheet.
  4. Allow the set tiles to cure in place for 15 to 30 minutes (depending on the paper and adhesive).
  5. Apply a damp sponge to the paper face to moisten it and hydrate the glue that holds it to the face of the tile. Don’t get it so wet the paper will fall apart. Don’t let it be too dry so the paper tugs tiles out of alignment while you remove it. Practice.
  6. Pull the paper from one corner or edge of the tile at an angle across the face of the sheet until the paper is off. If the tiles shift or pull out of the mortar – allow the mortar to cure longer and try again. To reduce the amount of pulling force, try using a knife to slice the paper into smaller sections and pull along the short side of the section.
  7. Adjust individual tiles as needed. Insert the long, clean edge of a straight, flat trowel into the joints between tiles and use it to align the mosaic.
  8. Step back from your work and take photos of small sections as you set them. Sheet lines can be much more visible in a photo than when you are focused up close. Examining your work in this way as you go allows you to see sheet lines that you couldn’t while setting and make adjustments while they are freshly set.
  9. Use hard shims, spacers, wedges, or apply tape to the surface to hold tiles in place while they cure.
  10. After curing, clean squeeze-through mortar before grouting and applying sealant at movement and expansion joints and changes in plane.

Plastic face-specific instructions:

  1. After setting the tile and making sure bond coat coverage is achieved, align the tiles to ensure there are no sheet lines.
  2. Stagger sheets as you install them to blend the grout joints from sheet to sheet.
  3. Cut squares or rectangles from sheets to overlap sheets as you install them to blend grout joints from sheet to sheet.
  4. Allow the set tiles to cure in place until firm. Usually at least overnight.
  5. CAUTION: The plastic on the face of the tile will cause a longer cure time for the mortar.  Many mortars cure through the grout joints. Because the
    plastic covers most of the grout joints, the mortar will take longer to cure.
  6. Pull the plastic from one corner or edge of the tile at an angle across the face of the sheet until the sheet is off.
  7. Clean squeeze-through mortar before grouting and applying sealant at movement and expansion joints and changes in plane.

I hope to see your next mosaic installation posted on NTCA’s social media channels! Have fun tiling and I’ll see you next time!

6 Questions for Evaluating Your Leadership and Achieving Your Mission

Many years ago, I regularly met up with a group of friends at a local breakfast joint for coffee. It was a bonding ritual for our bunch of diverse, young, high-achieving business types to relax and debrief. Whoever was in town would show up at our usual table, where we would discuss our successes and failures, new interests, and heartbreaks. We offered advice, stories, and, most of all, a safe place to be with a like-minded group of professionals. We bonded over earthy, soothing, and fragrant coffee that smelled like chocolate and promise. 

As much as I enjoyed it, our meetup for coffee was wrecking the one day of the week I had to catch up on my personal to-do list. The coffee caused me to speed up momentarily but crash later, leaving me with little energy to do much of anything. My stomach churned and my nerves were on edge. 

While this time was sacred to me, I had to reevaluate the coffee meetup to get back on track in my personal life. I realized I had to stop drinking coffee to maintain my energy and keep me at my best. The gathering was not about coffee anyway; it was about camaraderie and mutual support.

This is an example of how evaluation serves a critical role in even the simplest parts of our lives. As leaders, evaluation should be a major player in everything you do. Now more than ever, it is strategic to do an assessment of your organization’s, and your own, leadership skills, effectiveness, and style. When you have a full overview of the assets and opportunities for growth for you and your organization, you will be able to lead with clarity, confidence, and commitment. 

There are a few steps to accessing the data for you to be more effective and aligned with your goals. Take some time to review each point listed below. Ask the questions, collate the answers, and use them to advise both your strategic planning and your professional and personal development. 

1. Are your goals helping you achieve your mission? Before any goal is adopted, it should align with the organization’s mission and purpose. Review your goals — what purpose do they serve in accomplishing the mission for you or the organization? If it is a personal goal, have you determined your life purpose, and will this goal align with accomplishing it? Determine first the goal’s coherence with the overall mission before proceeding. 

2. Are your organizational goals clear, well-communicated, and actionable? Are all relevant parties aware, coordinated, and bought into the goals? Are the goals structured so that people know how they relate to their work and how it contributes to the mission?

3. Have you surveyed and gathered input from all pertinent sources, internal and external? In any evaluation, it is important to seek feedback from everyone involved. Each group or individual may have a different perspective, and with the full picture, you can proceed with confidence. Make these assessments a regular process. 

4. Establish an honest evaluation of the culture, systems, and operations of the organization and your leadership. Evaluations are only as good as the accuracy of the data. Ensure that the survey/analysis is done with confidentiality and as minimal bias as possible. If this is your personal evaluation, exercise the same caution, and care in the exercise.

5. How are you applying what you learned to improve your leadership style, strategy, and relationships? The actual applied use of the data to improve soft skills and practical operation is how the gathered information becomes meaningful. This is crucial to not only the organization’s success but also for ongoing credibility, morale, and ability to conduct further evaluations. This same concept applies if this is your personal evaluation, you will only be encouraged to make evaluations a routine procedure if you experience results from previous ones.

6. Upon review of the evaluation, are you comfortable and happy with where you are and where you are going? One key benefit of an evaluation is that you are able to assess your current career and life path. Use this valuable exercise to reappraise what the process showed you. Do you need to adjust your strategy and/or course? Your personal leadership style? Do you need additional training? 

Stepping back to do an overall analysis is very helpful in clarifying the assumptions, basis of operation, and the direction. A clear understanding of the many facets of the business, culture, strategic, financial, marketing, sales, operations, personnel, and customer and community relations will empower and guide everyone involved to work in alignment and harmony enthusiastically.

With proper evaluation, planning, and application of what you’ve learned, you will grow as a leader to better lead the team and your organization to greater success with improved morale and positive community impact.

The Hazards of Hybrids

Hybrid Shower

Today’s tile installations enjoy a tremendous amount of flexibility and creativity in methods, materials, and design. While a few decades ago there was only one option for waterproofing shower stalls, today we have myriad options. One tempting method is the Franken-shower, or hybrid shower system. But what risks are there and when is it the appropriate choice?

What is a hybrid?

With topical applications like B421 and B422 in the TCNA Handbook for Ceramic, Glass and Stone Tile Installation, which call for an ANSI A118.10 load-bearing, bonded, waterproof membrane, the membrane extends continuously from the drain to above the showerhead.

A membrane can either be sheet-applied or liquid-applied. Typically, a sheet-applied membrane calls for a 2” overlap at seams, corners, and penetrations. This is usually a band of the same material applied with thinset or an approved adhesive. A hybrid system is a liquid-applied membrane at corners and seams to create the waterproof overlap.

Some contractors who use this method do so simply because they don’t trust the science behind thinset bonding a 2” overlap to maintain a waterproof seal. The internet is replete with videos of contractors conducting their own tests to determine whether or not a system or material is actually waterproof. Other contractors prefer the ease of liquid-applied membranes over a seam. Still, others don’t like the potential build-up of overlapping membranes.

Trust the methods and manufacturers

Photo of hybrid seam installation
Hybrid seam installation. Photo courtesy of Bryan Cook.

That said, one of the most valuable resources we have available to us in the tile industry are ANSI standards and TCNA methods. When we use materials that meet ANSI A118.10 we can trust they will perform as a waterproof system. This being the case, we can and should trust the manufacturers when their materials are installed correctly. And in the TCNA Handbook, we find this language regarding the installation of waterproof membranes: “Bonded waterproof membrane must be continuous, including at changes in plane. Follow membrane manufacturer’s requirements for corners, seaming, and overlap.” Emphasis is mine.

Let’s take a closer look and see what challenges and risks tile contractors take when they build a hybrid shower system.

You don’t know what you don’t know

The first potential issue tile contractors should be aware of is introducing technical unknowns into the system. Potential material incompatibilities may arise when mixing waterproofing systems and materials. 

As contractors, we simply can’t know for sure how different materials will interact with one another. The liquid might require a mechanical profile to grab onto, or the sheet might not allow the liquid to integrate fully into the fabric, thus potentially allowing water to migrate behind the liquid membrane, leading to a failure. Since we can’t speak to the composition of the different materials and how they’ll interact, care should be taken in mixing components from different manufacturers. Ask yourself the following: If there is a failure, where would the fault lie? In the liquid seam? Or in the fabric material? How could that be determined? 

In this case, the failure, and liability, would lie squarely on the shoulders of the installer.

It’s worth noting that some manufacturers allow for a liquid seam mixed with their sheet membrane.  Since they are able to test in a laboratory setting, they can confirm the suitability and compatibility of these installations in their systems. This is key to deciding if a hybrid approach is the right one for your installation. If you prefer building your shower systems in this way, choose a system designed for it.

Partnering with a manufacturer benefits your client

The second issue you should consider is what the manufacturer recommends. A huge strength of our industry is the partnerships between installers and manufacturers. Our trade benefits from the support and knowledge that is available to each and every one of us. Following the recommendations of the manufacturers of the products we use is the simplest step we can take in our partnership.

A popular sentiment and statement is “my word is my warranty.” Unfortunately, it is not that simple. When companies write warranties, they are binding legal language. In other words, if you meet the terms of a warranty, they must as well. And these companies want to partner with us, and so they want to make sure you and your client are taken care of. Manufacturers want to stand with you behind their product. Often, manufacturers’ reps will even go beyond what’s required of them by the terms of the warranty to help installers in the field and to educate them. Of course, as noted above, that may be the start of a long-term partnership between the company and you.

Consider this: in 2020 we suffered an economic shutdown that could not be avoided due to COVID-19. Many small businesses went under, as they could no longer afford to stay in business. Others encountered health issues associated with our trade and must retire early or change careers. If in two years, a client needs a repair on their shower, but their installer is no longer in operation, who will they call? If they believe their shower was built as a system and is under warranty, they will call the system manufacturer. When the manufacturer comes to inspect the installation and determines that an unapproved hybrid system was “designed” by an installer who is no longer in business, what recourse will the homeowner have?

All this is to say we have an ethical obligation as professionals to our clients to make sure that not only is their shower built with proper methods, but proper materials as well. If we “design” our own hybrid system out of materials we happen to like, not only are we assuming all liability on ourselves, but we are actively voiding the client’s warranty, robbing them of their legal rights.

These are vital questions you should ask yourself:

  • Are you introducing technical unknowns into the system, and with them potential failures and health risks for your client?
  • Are you actively voiding your client’s warranty?

Perhaps this won’t change your mind on the subject. However, the fact remains that hybrids come with their own sets of hazards and risks.

Green building health and wellness – ceramic tile in a post-pandemic era

Over the past decade, the focus of “green building” has broadened from environmental issues to issues that also incorporate human health and wellness. From the start, green building codes (such as the International Green Construction Code, powered by ASHRAE A189.1), standards (such as ANSI/GBI 01), and rating systems (such as LEED) had in-depth provisions addressing resource conservation, climate change, and bio-diversity. Increasingly, provisions for occupant health, productivity, and overall well-being have been added. How will technical criteria continue to evolve in light of COVID-19? Much remains to be seen, but there’s no doubt that health considerations – particularly related to finishing product selection and use – will continue to be a widely-discussed topic in green building. 

Ceramic tile provides an inherent thermal mass that facilitates the moderation of indoor temperature swings and—in some cases—the possibility of natural conditioning to create more stable and comfortable indoor environments.

Up to now, what role have ceramic tile floors, walls, and countertops played in green building health and wellness initiatives? 

Initial industry efforts focused on educating designers about the inapplicability of various green building VOC emission criteria to ceramic tile. The argument was simple – it was impossible for an inherently-inorganic building product to emit organic compounds (much less, volatile organic compounds) into the air we breathe. Slowly, but surely, LEED, building codes, and major green school and office green construction programs implemented VOC testing exemptions for mineral-based inorganic surface coverings. Now, many of these programs acknowledge products such as ceramic tile as positive contributors to VOC-free interior spaces. 

Green building specifications for eco-friendly cleaning are also relevant to the tile industry. Ceramic tile is stain-resistant and easy to maintain. Often just water alone is an effective cleaner for tile but when more is needed, the ability to use mild, VOC-free cleaners for tile eliminates introducing harsh chemicals into daily living areas, contributing to a healthier environment. 

Ceramic tile provides an inherent thermal mass that facilitates the moderation of indoor temperature swings and – in some cases – the possibility of natural conditioning to create more stable and comfortable indoor environments. ASHRAE criteria addressing thermal comfort conditions for human occupancy, as well as ISO and CEN standards for ergonomics of thermal environments (both referenced by LEED), include compliance paths for natural conditioning through which the use of tile can help meet pertinent requirements. 

TCNA has announced a transformative collaboration to provide an industry-wide Material Ingredient Guide that can be used by representative products for compliance to LEED and other green building criteria. 

Green building’s focus on indoor comfort doesn’t only pertain to air quality; lighting conditions are also commonly referenced by green building standards. For example, a LEED criterion for interior lighting “to promote occupants’ productivity, comfort and well-being by providing high-quality lighting” quantifies light reflectance criteria for interior surfaces, and ceramic tile test methods and standards are often specified by designers.

The emergence of material ingredient reporting demands has become front and center in the green building conversation. Currently, green building health criteria are heavily focused on manufacturer transparency regarding the chemical makeup of products, including associated toxicological ramifications, and special attention is given to interior finishes and furnishings. The Tile Council of North America (TCNA) recently announced a transformative collaboration to provide an industry-wide Material Ingredient Guide. The guide will highlight ingredients broadly used by the tile industry, most of which are inert and naturally occurring – materials that construction workers and building occupants can feel comfortable using and living with day after day. The guide will also contain validated and industry-supported data, which can be used by representative products for compliance with LEED and other green building criteria. 

As can be deduced from the points above, early green building concepts of health and indoor “air” quality quickly transformed to indoor “environmental” quality. This way of thinking became more broadly described as “wellness,” with productivity and happiness as major pillars. Green building has come full circle back to toxicological considerations of products through material ingredient reporting criteria and human health remains as the most significant pillar of green building wellness.

Enter the COVID-19 pandemic 

Human health is already integral to the overall green building wellness discussion and feasibly, that discussion will continue to grow with much attention being given to the antiviral properties of building interior surfaces. In anticipation of this direction, there is much to learn regarding the technical aspects of COVID-19 before criteria can be developed for products such as floors, walls, countertops, and other surfaces with which we regularly come in contact. 

Besides the surfaces themselves, disinfectants are also likely to be widely discussed. Previously, the main focus on cleaners involved their toxicological ramifications, but that focus could be compounded with questions of disinfecting efficacy when considering a cleaner’s overall “greenness.” 

Furthermore, in the spirit of wellness, anything that can be done to alleviate building occupancy anxiety related to COVID-19 (and viruses in general) will be in demand. Some possibilities might involve using psychologically uplifting colors, incorporating natural ambiances, designing open spaces, and integrating surfaces that can be wiped down and easily maintained per guidelines of health officials. 

The next evolution in green building codes, standards, and rating systems contains a broad range of possibilities. The inherent green properties and design aspects of ceramic tile provide endless opportunities to answer these challenges.

Efforts to alleviate building occupancy anxiety related to COVID-19 (and viruses in general) will be in demand, including using uplifting colors, open spaces, and integrating surfaces that can be wiped down and easily maintained per guidelines of health officials.

TCNA lab adds antiviral testing 

To that end, TCNA remains heavily involved in green building initiatives and committed to keeping the North American ceramic tile industry-relevant as sustainability considerations continue to evolve. One specific example is that TCNA’s Product Performance Testing Laboratory recently expanded testing and research capabilities in response to global health concerns. New services include antiviral testing to determine the survival rates/durations of a host of viruses on different surfacing materials, including SARS-CoV-2, as well as the efficacy of common household cleaners to disinfect these surfaces. 

New TCNA lab services include antiviral testing to determine the survival rates/durations of a host of viruses on different surfacing materials, including SARS-CoV-2, as well as the efficacy of common household cleaners to disinfect these surfaces.

TCNA’s laboratory is already the only laboratory in the U.S. specializing in microbiological testing of floor, wall, and countertop surfaces; this recent expansion makes the lab uniquely positioned to provide testing on ceramic tile and other materials used in public and residential spaces. These tests and additional research will be helpful toward manufacturers’ product design efforts and could contribute toward the future development of standards to protect individuals against contracting and/or spreading viruses from contaminated interior surfaces. 

Today’s green building discussion is dominated by health-related issues. Even before the COVID-19 pandemic, human wellness had risen to be equally as important as environmental stewardship. Long after a vaccine for COVID-19 is created and available, it is likely that heightened health concerns will continue to be the new normal, and green building will inevitably evolve to incorporate new codes, standards, and rating systems. Given the inherent properties of ceramic tile and tile’s limitless design potential, the industry can be optimistic as we embark on a post-pandemic era in green building supported by the research of TCNA. 

Understanding PVA/Polyvinyl Acetate


I need some help in understanding PVA/Polyvinyl Acetate. I understand contractors sometimes add PVA believing that it will strengthen the bond. However, in wet areas, PVA is known to re-emulsify and weaken the bond. Do you have any knowledge of PVA you can share with me, such as failures from using PVA as an admixture, and can you help me understand if there are any plausible reasons to add it to cementitious tile setting materials?


I am not a chemist, but in the past, there were two additives for thin-set mortars. One was the PVA you asked about and the other is an SBR (styrene butadiene rubber).

PVAs are used in glues like Elmer’s® and are water-soluble. Previously PVAs were used on some thin-set mortars but carried a disclaimer that they were for interior dry use only, and are seldom used any longer. SBRs are not water-soluble and can be used in exterior (wet) environments.

PVAs are generally less expensive than SBRs, but they are not created equal. 

I hope this is helpful. 
– Scott Carothers, CTEF


I reached out to some manufacturers and they were extremely helpful and sent me a lot of information. Following is a summary of this information: 

• PVA (polyvinyl acetate) not to be confused with polyvinyl alcohol is still commonly used as a general-purpose adhesive in interior or non-water immersed applications.

Frequently it is used as a bonding agent or primer prior to the application of non-modified plasters and mortars to a cementitious substrate. An attractive feature in this application is the “rewettable” nature of the bonding primer when it contacts the fresh alkaline mortar, allowing some inter-diffusion of the polymer that can help bind the new and old cementitious material together upon drying.

PVA also finds extensive use in wall jointing compounds for adhesion, binding, and flexibility, where water immersion is not a concern.

The issue that can arise from the use of PVA is that under wet/alkaline conditions, the vinyl acetate side groups will hydrolyze to hydroxyl functionality, which renders the polymer more soluble and prone to swelling and migration. That’s an advantage as a rewettable bonding primer, but a severe disadvantage for long-term moist environments as the adhesive effect is diminished.

In general, PVA is not used as a mortar modifier in the tile industry because it is likely to encounter wet and water-immersed conditions where the polymer’s adhesive performance would be severely degraded.

The tile industry as a whole relies heavily on the use of vinyl acetate-ethylene copolymers (VAE or EVA) for mortar modification. While the vinyl acetate group is still present, these polymers exhibit significantly improved resistance to hydrolysis due to the presence of ethylene on the backbone and in some cases other monomers. This resistance to the hydrolysis permits their use in wet areas and can meet the ANSI 118 standards that include water-immersed adhesion testing. This class of polymer is widely used in drymix, modified tile adhesives, and doesn’t suffer from the performance deficiencies of the PVAs.

It is possible to improve performance further through the use of other polymers such as styrene-butadiene, acrylic, and versatic chemistries, but these are typically at a price premium to the VAE’s and most valued in specialty applications where increased performance is a must-have and tolerant to the additional cost. The vast majority of tile adhesives function well using VAE polymers and they provide a good value point for most formulations and applications.  

• The first spray-dried polymer available was a PVA (polyvinyl acetate) homopolymer. You have been familiar with this polymer for years – Elmer’s Glue. The problem with straight PVA polymer is its sensitivity to water and instability in the highly alkaline environment of hydrating cement. By itself, even after the PVA polymer has coalesced (dried forming a continuous film), exposure to water or sufficient moisture can re-emulsify the polymer resulting in loss of bond. Also, in the very alkaline, high-pH environment of hydrating cement, the PVA polymer experiences hydrolysis, which breaks down the polymer into the original monomers. Hardly any manufacturers use straight PVA polymers in their products today. 

The second spray-dried polymer available was actually a copolymer (2). It consisted of PVA (polyvinyl acetate) with the addition of an ethylene monomer. This produced a copolymer that had two very good attributes. One, the PVA portion of the copolymer had very strong bonding characteristics. These bonding characteristics include an affinity to bond to cellulose (wood). Second, the addition of ethylene into the copolymer made it much more stable under the highly alkaline environment of hydrating cement. This product has become known in the industry as an EVA (Ethylene Vinyl Acetate) polymer. Since then, chemists were able to modify the performance characteristics of these polymers even more by adding additional monomers to the chain. Monomers such as vinyl versatate and vinyl laurate have been added to substantially increase the polymer’s resistance to water. All of these variations generate a wide assortment of polymers from which the setting materials manufacturers may choose. A polymer with more ethylene will impart more flexibility to the finished product than one with less ethylene if the polymers are blended with the same cement/polymer ratio. The manufacturer must determine what the desired performance characteristics of a product should be and then choose the proper polymer and cement/polymer ratio to put in the finished product to achieve their goals.

• Polyvinyl acetate is essentially Elmer’s Glue type material. When put into the high pH of cement, PVA will hydrolyze to form polyvinyl alcohol. This is not a good thing – because as you mentioned, the polymer re-disperses when wet and will adversely affect mortars.

To my understanding, typically, tile adhesive manufacturers do not sell or promote the use of PVA for ceramic tile installations. Most manufacturers will utilize alternate proprietary lattices or alternate chemistries that are stable in cement and provide all of the proven required characteristics (e.g. strength, flexibility, moisture resistance, freeze/thaw stability, etc.). 

– Mark Heinlein, 
NTCA Training Director

Update! Respirable Silica Compliance

Hi everyone. I know you are all out there staying healthy, wealthy, and wise by following your local, county, regional, state, and federal guidelines to protect you, your employees, and your customers by preventing that pesky COVID-19 virus from finding its way into your lungs. This made me think this would be a great time to update you on the current state of compliance with OSHA’s Respirable Airborne Silica regulation. Just like COVID, you don’t want those tiny silica particles to build up in your lungs.

Here it is: There is no change.

That’s right. No change – yet. As I’m sure you know, the gears of government sometimes grind slowly, which seems to be happening with this regulation. In my experience, this usually means that those in charge of a program are taking a long, careful look before making changes to regulation while people are getting familiar with it.

cPaul Regina, TCNA’s Government Affairs Senior Specialist
Paul Regina, TCNA’s Government Affairs Senior Specialist

I recently checked in with TCNA’s Government Affairs Senior Specialist Paul Regina. Here is what Paul had to say about the state of the regulation:

There has been very little happening on the silica front.

In August of 2019, OSHA issued a Request for Information (RFI) regarding revisions to construction Table 1. The OSHA website says they are currently analyzing the data received during the RFI.

The current Unified Regulatory Agenda, an outline of when agencies believe they will be issuing regulations, indicates there is a Notice of Proposed Rulemaking dated June of 2020. Please see the following links for further information:

OSHA Silica Page: https://www.osha.gov/dsg/topics/silicacrystalline/

Silica in the Regulatory Unified Agenda: https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=201910&RIN=1218-AD18”

As Paul noted, the primary item being looked at is Table 1. This is where the regulation lists the tasks that can produce varying amounts of respirable airborne silica. Table 1 is too long to include with this article, but you can review it for yourself here: https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1153

Let’s take a simple look at Table 1. It has these three columns: 

  1. Equipment/Task
  2. Engineering and work practice control methods
  3. Required protection and Assigned Protection Factor (APF)
  • An Equipment/Task is something you do or a tool you use to perform a task in the process of installing tile. A common example is a wet saw used for the task of cutting tile.
  • An Engineering and work practice control method is the description of how the tool is used to perform the task in a manner that keeps the silica dust at a certain level.
  • The Required respiratory protection and APF column is broken into two parts. Fewer than or equal to four hours per shift, and greater than four hours per shift. Each column will list an APF number ranging from 0 (none) to 25. You add up the APF numbers for all the tasks you do in a shift to come up with a total APF.

Here is one example of how the table works: 

Apprentice installer using engineering controls to perform the task of cutting tile with a saw that has a built-in water delivery system to control or eliminate respirable airborne silica. No mask required.

For the Task of cutting tile, if you use an Engineering and work practice control method of using a saw that came with a built-in water supply system designed to constantly keep the blade wet while cutting (a wet saw), you can run that saw and cut tile with it for the whole shift without wearing a well-fitted, approved face mask designed to keep the tiny silica particles from entering your lungs. See if you can tell how I put this example together when you view Table 1 yourself. 

There is so much information on the OSHA website about this. You really should check it out. The FAQ section is really good. It lists the questions that you and I both have and provides us with answers that aren’t loaded up with too much of that wonky government regulation language. You don’t have to be a safety engineer to figure this stuff out. OSHA is trying to help us all understand.

If you read nothing else, read this direct quote from the OSHA website. Even if you’ve read this before, it’s worth reading again. I know it gets my attention when I am not thinking about this every day.

Crystalline silica is a common mineral found in the earth’s crust. Materials like sand, stone, concrete, and mortar contain crystalline silica. It is also used to make products such as glass, pottery, ceramics, bricks, and artificial stone.

Respirable crystalline silica – very small particles at least 100 times smaller than ordinary sand you might find on beaches and playgrounds – is created when cutting, sawing, grinding, drilling, and crushing stone, rock, concrete, brick, block, and mortar. Activities such as abrasive blasting with sand; sawing brick or concrete; sanding or drilling into concrete walls; grinding mortar; manufacturing brick, concrete blocks, stone countertops, or ceramic products; and cutting or crushing stone result in worker exposures to respirable crystalline silica dust. Industrial sand used in certain operations, such as foundry work and hydraulic fracturing (fracking), is also a source of respirable crystalline silica exposure. About 2.3 million people in the U.S. are exposed to silica at work.

Workers who inhale these very small crystalline silica particles are at increased risk of developing serious silica-related diseases, including:

A tile contractor and installer really should think about respirable airborne silica during every work task they do every workday on every worksite. I’ll guess that you don’t have to think too hard to come up with the tasks that create the single largest amount of respirable silica. That’s right – dry cutting tile or grinding tile or mortar with a grinder that does not have a shroud and dust collection system that includes a 99% efficient vacuum and filter or fixed water supply system.

Many talented installers are doing amazing scribe-type tile work these days. Be sure you are using a saw or grinder with the right water supply-type or shroud and dust collection-type system to avoid breathing in respirable silica. (Photo courtesy of Stoneman Construction LLC)

I see a lot of very talented installers doing amazing scribe-type tile work these days. If you aren’t using a saw or grinder with the right water supply-type or shroud and dust collection-type system, then please think about the task you are performing. Think about what you are breathing in. It’s not COVID-19, but once those tiny silica particles get in your lungs they are never coming out. They are going to keep building up and will eventually make you sick and can even be the cause of what ends up killing you.

If you haven’t yet become familiar with OSHA’s Occupational Exposure to Respirable Crystalline Silica regulation 29 C.F.R. § 1926.1153, here is what you need to do for you and your company:

  1. Check out NTCA’s website and read up on the information and follow the links we have provided to the professional tile community. https://www.tile-assn.com/page/PositionStatLibrary, towards the bottom of the page. 
  2. Download our standard compliance plan.
  3. Create your plan.

After you do that, the rest will follow and will become part of your daily safety habits and work practices.

During an informational session at Total Solutions Plus last year, I had the opportunity to ask an OSHA staff member involved with putting the regulation in place if there is a distinction between commercial or residential contractors and whether they were inspecting residential contractors for compliance. He replied that all contractors and jobsites are subject to inspection. He continued that if they happen to see a residential jobsite under work, they may check to see how things are going. 

At any worksite, the first thing they will ask is to speak to the Competent Person and to see your company’s Respirable Silica Control Plan. What is a Competent Person? A Competent Person is an individual in your company who knows all about respirable crystalline silica and your control plan. This is the person who identifies respirable crystalline silica hazards on your jobsites and who has the authorization to correct them right away.

Want to know why this is important? They figure if you have taken the time to prepare a plan and assign a Competent Person, then you have probably looked at your tasks, work practices, and engineering controls, and calculated your APF and many of the things necessary to comply with the regulation designed to protect you, your employees, other trades, your client, and anyone else who enters your jobsite.

Respirable silica exposure control information available on the NTCA website.

Not only is it the law, but it’s also important stuff for your health and wealth. Be wise, take the time today to review your plan or make a plan. And enter “OSHA” at tileletter.com to keep up to date with the latest announcements issued by OSHA throughout the year.

Thanks for reading. Remember to join NTCA’s training team at a virtual live Program in a region or time zone near you soon. Go to www.tile-assn.com and click on the Education and Certification section to see all of the training programs available to you. I hope you take advantage of these terrific benefits today!

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