Stone showers shine with preparation and precision

For this month’s Stone section, we take a look at stone showers completed by NTCA members Hawthorne Tile in Portland, Ore., and RMZ Custom Tile and Stone in Avon, Colo. 

Hawthorne Tile
Lake Oswego master bath

Lake Oswego master bathThis gorgeous master bath project for a Lake Oswego, Ore., residence was part of a three-month, full-home remodel, with extensive limestone used throughout, sourced from Artistic Tile. Due to hydronic heating in the home, the Hawthorne team set 150 ft. of 5/8” x 5/8” Whirlwind Smoke limestone floors to RH 141 in the TCNA Handbook.

Shon Parker (now with Schluter) was the project manager on the job, and admitted that widespread leveling was required prior to installation due to the wood substrate. “It gave us a chance to get the floors flat and do a barrier-free shower,” he said. 

In that shower, the crew employed the B442-18 integrated bonding flange method from the TCNA Handbook, with Schluter bonding flange and tileable cover. ARDEX 8+9 was used as waterproofing and crack isolation with Schluter Schiene strip. Wall tile was set over cement backer, also with Ardex 8+9. Another challenge in the shower was managing the incredibly fragile two-color limestone pattern – Artistic’s Smoke Limestone Claridges Stone Water Jet Mosaic. Parker said that Portland Marble Works – the Stone shower in Lake Oswego master bathfabricator who was doing the slab counters – waterjet-cut the inside corners “to keep the fine points of the tile from breaking on a wet saw,” according to the paper templates the crew created for all floor and wall cuts. Parker said Hawthorne Tile opted for the paper templates because the tile pattern was a unique shape. “The templates helped make perfect cuts each time, which helped the waste factor on such an expensive tile,” he explained. For the shower floor, the crew installed 130 feet of Lycian Aperlae Turkish Marble. 

The project, which had ceilings that ranged from 8’ high to 14’ at the high end of the vault, also sported 6” x 8” limestone tile wainscot everywhere in the bath except the shower, to complete the look of the room. 

Lake Oswego master bath with stone showers

RMZ Custom Tile
stone wave mosaic shower

stone wave mosaic shower seatThe design of a stone wave mosaic in a shower install by Miguel Ramirez of RMZ Custom Tile mandated extreme precision on the wall prep. “One of the challenges was to get the wall prep perfectly plumb and flat since on that particular wave tile every corner had to match the return piece perfectly,” he explained. 

“One of the things that we had to do prior to installation was to lay every row for the entire shower flat and mark every wall where the cut was going to be to have accurate piece return and continuation,” he added. “That was the most challenge that we had, since we were using the drop cut as a return.”

The marble mosaic project consisted of about 180 sq. ft. of First Snow Wave Mosaic by Daltile. 

“For leveling I started with the framing, making it as true as possible, then added shims,” Ramirez said. “I also used wedi panels as a substrate.” Afterwards, using a straight edge, he applied a final coat of Custom Building Products’ ProLite mortar where needed to make sure the surfaces stone wave mosaic shower drainwere flat and plumb. He used the same mortar to install the stone, with a coat of StoneTech Impregnator Pro sealer applied before grouting with Custom’s Prism Grout. After the grout cured for a minimum of 72 hours, he applied another coat of sealer, and voila! A beautiful stone shower! 

stone wave mosaic shower stone wave mosaic shower

Three technologies you need to integrate into your business

Get ahead of the curve by becoming familiar with three new technologies

One of the hardest things for a business to understand today is how, by how much, and why their customers have changed. There is no doubt that the changes that have taken place in the past 10 years have been more profound than any in the past thousand years as related to commerce. To ignore this reality and try to do business “the way we have always done it” is a fast track to irrelevancy and bankruptcy. I would like to explore here some of the major factors that are influencing your customer and more importantly, how you can use this information to keep them coming back to your business.

Humans change core beliefs and values very slowly but they do change what we often call “habits” relatively quickly and easily. Think of your own shopping patterns. Are you buying the same groceries you bought five years ago? You would most likely say “no” because your circumstances have changed in the past five years. You may be eating healthier (or the opposite!), you may have shipped a voracious eater off to college, or you may have added a new member to the family. Think about what you now have for dinner and lunch and how that likely differs from five years ago. Think where you are buying your food and even what food you are buying. Likely it is very different due to the reasons above and for even more reasons. 

But what is likely enduring is that you have standards for the quality of the food you consume as well as how you consume it. You have probably not stopped using a fork and knife and switched to just eating with your hands (or maybe you do if you have a burger now and then!). Our core behaviors, learned as children, are harder to change and remain more constant. The way we shop changes as we grow; where we shop also changes with our lifestyle and influences of our society. 

The mobile phone has been one of the greatest “disruptors” that we have ever seen in retail. Given the ability to instantly access not only information but also input from family and friends about every purchase has changed the way consumers view and interact with retailers. Long gone are the days of getting in your car to drive to different stores to compare prices; they are now available right in your hand. Gone also are the days of waiting to ask friends or family their opinion of a desired purchase or feedback after the purchase, such as “What do you think of my new kitchen floor?” Now the opinions and feedback occur in real time before, during, and after the purchase, making the path to purchase very different from what it used to be.

Technology beyond the phone is also having a profound impact. There are three technologies in particular that you need to not only pay attention to – but more importantly – have a strategy of integrating into your business. These three technologies are Augmented Reality (AR), Conversational Commerce and the Internet of Things (IoT). Each of these technologies is having an impact on your customer’s shopping journey and therefore needs to be part of your strategy today.

Augmented Reality

Augmented Reality is the ability of computers – and more often mobile phones – to insert objects into a real environment. The use of this technology is growing daily. Think of your customer taking a picture of their kitchen and then with a few swipes adding a new floor, cabinets, appliances and lighting, totally customizing the scene. And because this technology can also provide exact measurements, the customer can decide how much tile is required, the size of the cabinets that they can have, the size of the appliances, and get an accurate cost estimate for that makeover. This is not science fiction; it is being done today by many retailers for components of it, and it will not take long until all of this ability becomes integrated into one simple app. Remember, one of the things the new consumer has learned to love is DIFM (Do It For Me), and there are thousands of apps and companies doing just that.

Conversational Commerce

Conversational Commerce, (think Alexa and Google Voice) is just in its infancy and yet it is quickly moving from the home to the auto to the mobile phone and to every part of our lives. People love to talk to their devices even more than just typing or swiping. As these helpers get more sophisticated, consumers will rely more and more on them to assist them in day to day living. They will ask Google or Alexa to show them what a new bathroom would look like, give a price and schedule an installer to make it happen. Voice is becoming the next frontier for acquiring products and services. These artificial intelligence devices will become smarter and smarter and more integrated into our everyday lives and that means how we buy things.

The Internet of Things 

The Internet of Things (IoT) is simply adding smart technology to devices that can then be controlled or programmed to behave a certain way. Imagine your refrigerator with the ability to schedule a service visit when it knows that a part is failing, or a heated floor in the bathroom that turns on when you tell the shower to start and brings the floor to a preset temperature based on ambient temperature and the preference of the individual taking the shower. The shower will also be the desired temperature for the individual based on the family member’s preference. The IoT device is imbedded in the water lines and in the floor heat controls. There is no end to how the IoT will change the way we live and interact with our environment. Try telling a 16-year-old today that there was a time that you had to get up and twist a dial to turn on a TV, and that to change the channel you had to get out of your chair, walk to the TV and turn the dial. This behavior seems almost quaint today. Just think about most of what we now do that will also seem quaint in 10 years!

The three technologies that I described are here today; they are also integrating with each other and exponentially changing what is possible and what we will be experiencing in the VERY near future. As a business, you need to be aware of each of these technologies, hire people who are familiar with them, get your own Google Voice and/or Alexa, as well as download AR apps to your phone and play with them. 

Remember the words of Jack Welch (which, by the way, GE failed to listen to): “When the rate of change outside your business exceeds the rate of change inside your business, the end is near.”

For more information about James Dion and Chicago-based Dionco, Inc., retail, consulting and training company, please visit 

Critical planning for curbless shower success

This article focuses on design concepts that should be incorporated into plans and specifications for curbless showers in new construction. Other challenges and options come into play for curbless showers when these design requirements have not been included (e.g., remodel projects) and the additional requirements are for a curbless shower to also be “accessible,” or ADA compliant. 

A few factors are fueling growing popularity in the United States of curbless showers, also commonly referred to as “zero entry” showers. An aging population is a main one. Whether an older individual is “aging-in-place” or has opted to relocate to a community or facility, a curbless shower is often more desirable and sometimes even necessary to help people cope with physical changes that they may begin to experience that can make showering difficult or even dangerous. At the same time, thanks to a proliferation of fashion-forward products and systems that facilitate elimination of the shower curb, people of all ages are “going curbless” purely for the sophisticated, streamlined design.

Regardless of the reasons for it, the noticeable shift toward curbless showers is making it increasingly important for building design professionals and tile contractors to know the unique and critical shower design and installation requirements when there will be no curb at the shower entry to function as a dam. Proper planning and high-tech installation materials and shower components are key to containing the water and channeling to a drain, all of which can be applied to the even more challenging goal for the entry into the bathroom to also be transition-free. 

Recessing the subfloor

A shower cannot be totally curbless unless the subfloor where the shower will be constructed is recessed, and the recess is sufficient to accommodate the combined thickness of all the materials below the tile. The size of the shower and placement of the drain(s) are key factors in determining the required recess, as they’ll dictate the required thickness of the floor mud, foam shower base, or other material used to form the sloped base for the tiled shower floor. 

Diagram of a shower base constructed of a topically-waterproofed mortar bed (bonded to concrete) and a bonding-flange drain, recessed to facilitate a curbless shower entry

Diagram of a shower base constructed of a topically-waterproofed mortar bed (bonded to concrete) and a bonding-flange drain, recessed to facilitate a curbless shower entry

The installation method or system that will be used is also key, as they vary in thickness. Some are thinner by design specifically to make it easier to construct a curbless shower. The use of an ANSI A118.10-compliant, thin, load-bearing waterproofing membrane directly below the shower floor tile – instead of a traditional shower pan membrane underneath a mortar bed – results in a lower profile system without sacrificing functionality. Bonding flange drains and linear drains also offer reduced thickness of the shower base, in many cases requiring no more than 3/4” (mortar bed or preformed pan) at the thickest point, whereas a traditional clamping ring style drain, such as those shown in many TCNA Handbook methods, (e.g. Method B415) requires a 1-1/4” to 2” mortar bed.

A single sloping plane is possible with a linear drain

A single sloping plane is possible with a linear drain, which gives a streamlined appearance and allows large tiles to be used; just be sure the tile layout on the walls will facilitate the non-level floor perimeter.

Thus, for the tile contractor to be able to deliver a curbless shower, the specifics of how the shower will be constructed must be determined at the outset so their dimensions can be incorporated into the building’s rough-in plans. This is much earlier than is often the case, which highlights the importance of advance planning when it comes to curbless showers.

Another piece of the puzzle is drain location. In many cases linear drains and bonding-flange drains can be located in various places within a shower compartment – at any of the shower walls, at the shower entrance, or mid-floor. Perhaps more important than its impact on the required floor recess, ideal drain location is critical to how the shower water will flow and drain. Effective draining – versus aesthetic preference – should drive the placement decision. In many cases placement away from the shower entry is optimal. 

During the design phase, consideration should also be given to defining the shower floor space. In other words, what are the extents of the shower floor? In some cases, in larger showers or open-design showers where the shower floor freely flows into the restroom areas, a secondary drain may be required to collect any water that may flow out of the shower compartment or overrun the main shower drain due to the momentum of the water. Also, showers with multiple heads/jets may require additional drains to handle the water flow.

Slope of the shower floor

The International Plumbing Code (IPC) requires a slope of 1/4” per foot (IPC 417.5.2 Shower Lining) for shower floors, which is echoed in the TCNA Handbook shower receptor methods. Recessing the subfloor or substrate under a shower allows the finished floor to start sloping from the height of the floor outside the shower, rather than building up a shower base to provide slope to drain, as required when there is no recess in which to countersink the shower base, which therefore requires a curb. 

Sometimes less slope is specified in a curbless shower, such as 1/8” per foot. In some jurisdictions, a slope of 3/16” per foot or 1/8” per foot could be allowed for a roll-in shower designed to comply with the Americans With Disabilities Act (ADA). However, it is important to note that reducing slope greatly reduces the draining efficiency of the shower. There just isn’t enough slope to properly evacuate the water, which can result in standing water at any given time, a different possible safety concern. In addition to considering these tradeoffs, design professionals should also consult local building and plumbing codes and officials on a regular basis to ensure baseline compliance with the most current requirements, including the latest ADA parameters when ADA compliance is also intended. 

Although tile contractors should in theory be able to follow specifications as written, when less than 1/4” per foot slope is specified, it may be worth reconfirming the desired and/or necessary slope with the general contractor and/or project design professional before proceeding. The same could be said for the specified slopes and drains, and the resulting floor recess needed to accommodate them. If a reconfiguration is necessary, a proactive approach might avoid finger pointing and delayed payment later on, or help to build relationships that will lead to more work. 

But regardless of how or when potential design issues are addressed – some contractors prefer to wait until they’ve been awarded a job – what’s not optional is a good understanding of the critical design elements for curbless showers. Even when it’s a designer’s responsibility to design a shower that’s curbless and drains effectively, tile contractors will no doubt discover – and therefore have to address – various design and rough-in execution flaws as part of the process.

Safety precautions for the newly-released silica standards


We are reaching out to touch base on the newly-released silica standards in construction. You guys come in contact with a number of other contractors on a day-to-day basis. We are wondering what safety precautions other contractors are taking to better align themselves with OSHA’s standards.

We had OSHA inspectors on a project today at a local college. They have interviewed our employees in regards to company policy, etc. We have yet to receive feedback from our guys or receive formal notification from the GC.

Our guys use vacuums with dust masks when grinding tile or mixing mud. We grind outside when possible. Other than that, it has been a supervised common-sense approach to what we feel is appropriate. Obviously we want to remain compliant and keep our guys safe. We are looking for any input or direction you guys can provide to help us better formulate a compliance policy to keep everyone happy and safe. Look forward to hearing back from you.


Thanks for getting in touch with us about this very important topic.

NTCA has prepared some documentation for you to develop a Silica Exposure Plan to help you understand and meet OSHA Regulation requirements. It can be found on our website at this link:

NTCA is working with experts from the Tile Council of North America (TCNA) and OSHA to increase our knowledge and stay up-to-speed on the latest developments of the OSHA Silica Regulations. An important aspect of the regulation is known as Table 1. This table lists the tile installation jobsite tasks that commonly create exposure to silica dust. The tasks on this table are currently in the process of changing. We do not yet know exactly what changes are being made, but we anticipate that the tasks will become better defined for us to better plan how to stay in compliance.

NTCA always discusses silica exposure and techniques to avoid creating dust, or ways to properly capture the dust we have to create, at all of our training programs such as NTCA Workshops and NTCA Regional Training events. When these programs are near you, please be sure to attend. 

We are also working with TCNA and OSHA to present two in-depth silica sessions and workshops for Coverings. Attending these workshops at Coverings will be a great way to gain direct knowledge about what is required for your company to be in compliance.

Being in compliance is quite a bit more than simply moving the grinding outside or using a vacuum and a dust mask. You must have a written exposure control plan with documents that detail how you will handle certain dust generating tasks for every job and every job site. You must also have a person identified as the “Competent Person” on every job site that will ensure your plan is in place and working on the job.

Knowing a jobsite-specific task’s “Personal Exposure Limit (PEL) is a major component of determining whether your jobsite’s require certain control measures. PELs are cumulative for multiple tasks and for the length of time persons are exposed to the task. It is a lot to discuss in a simple email, but it all adds up to determine the level of protection or controls required.

As I mentioned, grinding outside isn’t necessarily an easy solution. We must protect other trades and the general public from exposure to any silica dust contractors generate on our jobs. General contractors must calculate the PELs for all trades contributing to the overall PEL for the entire job site. They will want to know how you will be containing or reducing dust-generating practices and you will want to know how the other trades are doing the same and contributing to the overall job site environment.

You will want to become familiar with the engineering controls or mechanical control measures that can be put in place to reduce dust below certain exposure levels, or eliminate it entirely. An engineering control might mean using a carbide scoring tool to score and snap cement board instead of using an angle grinder to cut it. Others range from tools we already use every day such as wet saws and snap cutters to grinder shrouds and HEPA vacuums. Speaking of vacuums, not every Shop-Vac®-type vacuum works to collect silica dust and keep it from becoming airborne. Specific vacuums are required.

Simple dust masks don’t do the trick. If engineering controls alone don’t keep your job site PEL beneath minimum thresholds you may need to look at a respirator program. Such a program may require fitness and physical testing of your employees to ensure the respirators work and they are healthy enough to wear them.

The key is to understand Personal Exposure Limits, tasks listed in Table 1, Engineering Controls, writing a company plan, providing employee training, and putting your plan in place. It sounds like a lot, but it is a good health and hygiene best practice for you and your employees. 

I may be making this sound more complex than it might actually be. Please take a look at the documents available on the website and read what OSHA has to say on their website at I expect you will be getting some excellent feedback from your employees. I encourage you to contact the OSHA inspector that visited your job site – I am sure they will be willing to help your understanding of the regulation. 

Mark Heinlein,
NTCA Training Director

What should the relative humidity percentage be to set tile?

Laticrete logoQUESTION

I am looking for the relative humidity percentage in a newly-poured concrete slab to be able to set tile. 


Unless installing an UN-bonded mortar bed, all TCNA Handbook methods for installing on concrete call for the slab to be well cured, dimensionally stable, and free of cracks, waxy or oily films, and curing compounds.

Some manufacturers of uncoupling membranes may have instructions allowing for the use of their membrane over newly poured concrete since the membrane may act as a conduit for the concrete to properly cure during the early stages of the curing process. The membrane manufacturer would have to be contacted to verify and support this for use of their product.

Installing on a slab with excessive internal moisture can be problematic. Installing on a green slab presents the potential for additional unknown factors.

Many factors come into play when considering relative humidity (RH) in a slab. In a new slab, curling of the top surface (especially at control joints) may occur causing the slab to exceed variations in flatness tolerance for a tile installation. As a green slab cures (and curls), debonding or cracking of the tile bonded to it may also occur. Your 2018/2019 NTCA Reference Manual includes an excellent discussion on Ceramic Tile & Stone Installations over Concrete Substrates on pages 50 – 61. The troubleshooting guide on page 54 includes a discussion of identifying problems/causes/cures for excessive internal moisture in a concrete slab. It also references the test procedures for determining safe levels for moisture in a cured slab.

In addition to consulting the NTCA Reference Manual and membrane manufacturer, it is important to involve your setting-material manufacturer in the discussion for selecting the correct bonding and grouting products to adhere to and properly handle the moisture emanating from the slab. 

Mark Heinlein,
NTCA Training Director

Waterproof membrane for concrete substrate

Laticrete logoQUESTION

I will be tiling a shower/bathroom house at a campground this summer. The floor substrate will be concrete and the walls will be masonry block. The architect did not specify any waterproof membrane for the entire job. I am wondering if this will be okay since it’s all concrete. Should I suggest some kind of waterproofing/crack-isolation membrane? If so, could you refer me to the place in the TCNA Handbook that explains this?


Thanks for contacting the NTCA. We encourage everyone to use industry-recognized methods found in the Tile Council of North America Handbook for Ceramic, Glass and Stone Tile Installation, and ANSI. There are a variety of shower methods that would work with the installation type you described (See methods B421 and B422 TCNA Handbook). All incorporate waterproofing that meets ANSI A118.10. standards. 

Having the appropriate slope and drain connection is crucial in every shower design. Water can pass through grout, stone and many tiles, so installations need waterproofing beneath the tile. Although the subsurface is block and concrete that may not be harmed by water, water can pass through these surfaces and get into areas where it is not desired. When waterproofing is not used and water soaks the block or concrete, those areas can continually remain wet, discoloring stone tiles and grout. A wet subsurface also creates a source of moisture that can encourage mold growth when organic materials like soaps are left behind. 

Robb Roderick,
NTCA Technical Trainer

Why we all need Why Tile

Understanding the who, why, what, when and how of one
of the industry’s more important initiatives

Launched during Coverings 2017, the Why Tile® program is the tile trade’s first industry-wide initiative to demonstrate the benefits of ceramic tile. While the initiative is a definite positive for the general tile industry, many tile contractors have yet to discover how the program can benefit them. By understanding the program better, and the resources it offers, contractors just may discover that the program is not only a good resource, but an important tool in helping them provide valuable information to their clients. 

Who is Why Tile?

As mentioned, Why Tile, coordinated by the Tile Council of North America (TCNA), is the tile industry’s only joint initiative to provide the market with education and information about tile. Before its launch, key stakeholders from the installer, contractor, manufacturer, distributor, and retailer sectors all collaborated to create this massive undertaking. Today, leading industry organizations and manufacturers contribute to the program to continue the growth of its already-robust content. Some of the noted industry organizations that support Why Tile include Ceramic Tile Distributors Association (CTDA), National Tile Contractors Association (NTCA), Ceramic Tile Education Foundation (CTEF), Tile Contractors Association of America (TCAA), and Tile Heritage Foundation (THF). 

Why the industry needs Why Tile

While Why Tile started out as a massive marketing and education initiative designed to inspire consumers and provide information on all of tile’s benefits, it has become much more in the past two years. When launched, offered consumers inspiration, ideas and advice on tile. The site has expanded to include an extensive commercial section that provides industry-specific content and tools for architects, designers and specifiers. The commercial section even includes case studies, application information and a resource library. 

Kathy Meyer, TCNA’s Director of Marketing, says the content and topics on are still expanding, allowing the site to become a good information source for the industry and their clients. “Why Tile provides information that also goes beyond style to explore how tile can improve the functionality of any space, and how ceramic tile compares to other surfaces, including plastic floors,” she said. “Why Tile provides excellent content and examples to share with customers and employees.”

Meyer stresses that is a useful resource for contractors as well. “The information and ideas at can help a tile contractor articulate, with consistent and valid messaging, the benefits of using ceramic tile for their customer’s specific industry, application, or project,” she said. All the resources available on the site are free and are ideal in helping installers explain certain aspects of tile to their clients, including selection, design and maintenance tips.

What about those resources?

For those who haven’t visited, the resources that it offers are numerous. For installers and their clients, it provides pattern ideas and an impressive design gallery to help with the creative stages of the project. The site also includes an “Easy Care” page that is ideal to share with clients after a project is complete. The page explains how clients should maintain and protect their investment (and the installer’s hard work) for years to come. 

Meyer explained that the Why Tile Partners web portal is another important – and free – resource installers may want to consider. “Why Tile Partners can take full advantage of these resources to help themselves, their employees and their customers become educated about the smart and beautiful choices with ceramic tile,” she explained. 

After they register, the portal offers Why Tile partners four key resources: the Why Tile Activation kit, Why Tile logos for co-branding opportunities, monthly social media posts, and a comprehensive Why Tile presentation that amplifies the strengths of ceramic tile. The monthly social media posts include text and images partners can use on their own social channels as long as they include the hashtag #whytile.

NTCA developing installer-centric content

In response to trending topics, technical advances, and educational needs, Why Tile is continuously adding content to its site. Meyer says to expect to see even more new resources and content on the site this year. 

But 2019 will be a milestone year when it comes to tile contractors and The NTCA is taking part in a joint project with the Why Tile team to produce content and resources specifically with tile contractors and installers in mind. “We are excited to see this joint venture take shape,” said NTCA Executive Director Bart Bettiga. “I look forward to seeing what the venture produces. Plus, I think is an excellent asset to use to communicate the importance of using qualified labor to residential and commercial audiences.”

How to become more involved

Meyer said Why Tile is always looking for new partners. Anyone who is looking to become more involved in the program can register to become a partner by visiting the Why Tile Partners web portal or reaching out to Meyer or Roxanne Morris.

What do you use to clean 100% silicone caulking


I wanted to ask you about what you used to clean the 100% silicone caulking when you did the caulking demonstration at a recent workshop? Thanks!


I used water with a few drops of dishwashing liquid in a spray bottle. Install sealant, spray the bead of sealant, then strike off excess and wipe on paper towels. If you want to strike again to dress it up just spray the area again. This will keep it from sticking. Denatured alcohol, window cleaner, and a variety of other things are often used in the same way. Whatever you use make sure it is approved by the manufacturer of the sealant. Using non approved chemicals or methods can lead to issues like incomplete curing of the sealant joint. 

Robb Roderick, NTCA Technical Trainer

Wood frame construction recommendations for tile and stone floors

Building design guidelines and additional measures to accommodate sustained concentrated loads 

This article was derived from an article by Dr. Frank Woeste, P.E., Professor Emeritus at Virginia Tech and a wood construction consultant, and Peter Nielsen, cofounder of MGNT Products Group, LLC, a consulting and product design company for the tile and construction industries. This version of the information was generated by NTCA to provide a brief overview of their wood framing recommendations for hard surface flooring.

Two kinds of designers are involved in construction: design professionals responsible for performance and structural integrity and interior-focused designers responsible for the final appearance. Although they have very different roles, some of their decisions should be coordinated. For example, they should join forces when hard surface flooring – like tile and stone – is selected since these materials are on the heavier end of the spectrum, requiring more robust structures to support their weight. Hard surface floors are also more susceptible to problems than flexible floor types are when the weight of a concentrated load, like a dreamy kitchen island, is not adequately designed for. This article provides guidelines to design professionals for specifying adequately supportive structures for tile and stone floors in new construction wood frame buildings.

Designing for dead load

Sagging book shelves illustrate the concept of creep deflection; over time, shelves that are not strong enough for the weight they are loaded up with will bow.

A key factor is “dead load,” which is the cumulative weight of everything that a structure needs to support continually, including the flooring. When the actual dead load in a wood frame structure exceeds what was designed for, it over stresses the wood framing and over time can result in excessive “creep deflection,” a permanent bowing of the structure. An easy way to envision creep deflection is to picture an overloaded bookcase. The shelves will bow over time – and permanently – under the weight of the books.

Similarly, a home or building can be overloaded, for example by being structurally designed for luxury vinyl planks (LVP) flooring rather than the interior designer’s vision for ceramic planks. Some creep deflection is inherent and expected in wood frame construction, and not an issue for tile and stone floors. Overloading is what causes excessive creep deflection, possibly beyond what a tile or stone floor can withstand. Potential for and severity of a tile flooring issue because of excessive creep is tied to the amount of overloading and passage of time.

Weighty design features, like large kitchen islands with solid surface tops, and heavier-than-usual appliances, such as a Sub-Zero refrigerator, are examples of concentrated dead loads that additionally need to be designed for, structurally. This is true regardless of flooring type, but something to be especially aware of when the floor will be ceramic or stone tile. That’s because rigid, hard surface flooring materials are where concentrated overloading of a wood frame structure might become visually apparent, in the form of cracks, due to their inability to bend.

Baseline weights to factor into dead load 

To facilitate adequate structural design for tile and stone floors, the TCNA Handbook for Ceramic, Glass and Stone Tile Installation provides the approximate per square foot weight of tile, stone, and installation materials, individually by material type (i.e., 1/2” thick cement board weighs 4 lbs. per square foot) as well as cumulatively by installation method (i.e., Method F144 weighs 8 or 10 lbs. per square foot, depending on whether 1/4” or 1/2” cement board is used). Using this information, located in Appendix B, building designers can arrive at accurate dead loads. 

Appendix B of the TCNA Handbook is a compilation of material and system weights.

Method F141 Stone weighs 23 pounds/square foot with a 1-1/4” mortar bed.

Accurate dead load is important because dead load influences the maximum span (length) of wood joist that can be used, per International Residential Code (IRC) guidelines. These guidelines provide maximum allowable joist span separately for an assumed dead load of 10 psf and 20 psf. Remember though, dead load is not just the flooring. So, while the separate span tables may be generally used according to flooring type (e.g., follow guidelines for 10 psf dead load when lighter floorings like carpet will be installed, and guidelines for 20 psf dead load for tile and stone), one should not assume they apply in all situations. Additional dead load could be present from other elements, causing total dead load to exceed 10 psf where a lighter floor finish will be installed or exceeding 20 psf where ceramic or stone tile will be installed. Not to mention, some tile and stone installation methods on their own exceed 20 psf, which demonstrates that IRC span tables aren’t always enough.

Research indicates that an even more important consideration for tile and stone floors in wood frame construction is the thickness/stiffness of the subfloor, although not necessarily because of system-creep-inducing overload. Rather, the subfloor sheathing could simply deflect (bend) between joists under an applied load more than a hard surface tile can withstand, even if the sheathing is otherwise adequate within the full design scheme to support the expected loads. 

In Method F144, the wood subfloor can be 19/32” thick or 23/32” thick and relates to whether the installation methods falls under the residential or light commercial service rating.

This industry-specific consideration, not addressed in IRC, is addressed in the TCNA Handbook through more stringent deflection limits. Specifically, the TCNA Handbook limits deflection under concentrated loads, whereas IRC deflection limits are for uniform loads. What this means for building designers is that the minimum subfloor thickness/stiffness required by code for strength may not be enough. A thicker/stiffer subfloor may be needed to limit subfloor bending between joists. More robust framing may also be needed, again to go beyond the strength consideration to further limit bending related to concentrated loads. The heavier and more concentrated the load, the greater the need to beef up the floor framing to limit bending.

An example: the large kitchen island

As an example, consider the large kitchen island scenario. With 30mm (3cm) thick stone tops and normal contents being stored inside, this popular kitchen feature could present a 40 psf dead load, calculated by using the square footage of the island’s footprint as the area. In service, the framing and subflooring directly below and around the island is subjected to a substantial sustained load that produces creep deflection, but only in that area. As such, for hard surface floors, building design should incorporate more stringent framing requirements in areas where concentrated dead loads are expected, with kitchen islands a particular focus because of their widespread use. 

Because this kitchen island is oriented parallel with the wood joists, its weight is on fewer framing members.

It’s not practical, though, to expect a customized calculation and specification for every kitchen island. A more practical approach would be to follow general guidelines that are widely effective and easily incorporated into documents and processes. 

Since large kitchen islands are frequently paired with ceramic or stone flooring, it makes sense to have the following structural design parameters specifically attached to them: 

  • For solid-sawn and I-joists: joist spacing beneath kitchen islands shall be reduced by one-half and indicated on the joist framing plan.
  • For floor trusses: floor trusses beneath kitchen islands shall be doubled. 

Designing for hard surfaces checklist

These suggestions are in addition to the following recommendations, some of which were provided earlier in the article but are restated here in the interest of supplying a complete “designing for hard surfaces checklist”: 

  • Prepare construction documents that contain:

º the TCNA Handbook installation method

º the weight of the installation method (from TCNA Handbook Appendix B)

º the footprint of the kitchen island (and other heavy equipment)

º a specification that joists shall be doubled, or spacing reduced by half, beneath an island

  • Require floor system designs based on a “total load” that includes the actual weight of the installation method
  • Upgrade subfloor thickness (above what is given in the TCNA Handbook method being used) 
  • Require strongback bracing for floor trusses to minimize differential deflection of joists
  • Offer customers (homebuyers, owners) floor framing and subfloor “upgrades” for added protection against the likelihood of tile and grout cracks and annoying floor vibrations

The generalized “overbuilding” that some of these recommendations suggest may not seem an easy ask in an industry that prizes value engineering. But they do have enormous value – not in material cost savings – but from having effective boilerplate solutions to a common design challenge that are also practical with respect to implementation. Tile and stone professionals would be well served if these guidelines were better known and understood by building designers. TileLetter readers are encouraged to help make that happen by circulating and posting the information freely.

Should you tile to the walls or leave a small space?

When installing floor tiles, should you tile to the walls or leave a small space for movement and flexibility?

To answer your question about whether to leave a space where a floor meets a wall – Yes! A gap of approximately 1/4” should be left at all changes in plane (for instance where a floor meets a wall) around the perimeter of the installation. This gap should be present in the underlayment and tile. If no trim will be installed to cover the gap, a “soft joint” can be made with appropriate sealant, or certain trim profiles can be installed to accommodate movement and expansion. This gap should also be left where tile abuts cabinetry, pipes or other permanent fixtures. Any other change in plane such as where a wall meets another wall must also have a soft joint installed to allow for movement and expansion. Also, expansion joints must be properly placed and installed in the tile field depending on the location and size of the installation. Additionally, control joints and saw cut joints in concrete must be honored through the surface of the tile to avoid future cracks in the finished installation. These specifications and the many, many other details related to a successful tile installation can be handled by your qualified contractor and certified labor.


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