If a shower floor slope is 1/4″ per foot are other horizontal surfaces also 1/4” per foot?


I have a quick question about how much slope a shower bench or shower dry-off area should have.

The TCNA Handbook states that “All horizontal surfaces, for example shower seats, sills, curbs, etc., must slope towards drain.”

Shower floor slope is 1/4″ per foot. Are the other horizontal surfaces (bench, etc.) also supposed to be 1/4” per foot?


Yes, the correct slope for all horizontal surfaces is 1/4″ vertical (minimum) up to 1/2″ (maximum) for every 12” of horizontal run. 

– Mark Heinlein,
NTCA Training Director

Uncoupling membranes methods and standards: a timeline

In 1987, a new product category was launched in the North American Tile industry called “Uncoupling Membrane.” The product – an orange membrane – was made of polyethylene, ribbed in one direction and had a polypropylene mesh heat-bonded on the underside. This product was only 3/16” (4.5 mm) thick and 3’ 3” (1 m) wide and only weighed 45 lbs. (20.4kg) for a 323 sq. ft. (30 sq.m.) roll.


Surprisingly, one of the most popular uses of this very flexible and non-rigid membrane was over plywood substrates, including over a single layer of plywood. In 1999, the first detail for a “Proprietary Membrane” with double layer of wood subfloor on 24” (600 mm) on-center (o.c.) joist spacing was introduced to the TCNA Handbook (F147). Then, only two years later in 2001, a second detail was added to the Handbook for going over a single-layer plywood floor on 19.2” (480 mm) o.c. joists with an “uncoupling system.” There was no reference to the manufacturer under limitations. The term “uncoupling” was substituted for “proprietary membrane,” and a definition was added to the prologue:


“Uncoupling Systems: A system that separates the finished surface from the substrate to allow the independent movement between the two and prevent the transfer of stresses to the tiled surfaces.” 

For those of you who attended that meeting in Clemson, S.C., you will remember that this was the year that the TCNA Handbook Committee voted to approve removal of anything in the Handbook that had proprietary names, which included the section for “Floors Sound Rated.” Then around 2006-2007, a directive was issued to describe a “DITRA”-like product. This definition resulted: 

“Uncoupling membrane: A plastic membrane system geometrically configured to provide air space between the tile and the substrate to allow independent movement between the two and limit the transfer of the stresses.” 


The last detail added to the TCNA Handbook for uncoupling was in 2007 for “Young Concrete” Detail F128. The concern with young/green concrete is that the concrete slab has large amounts of residual moisture that still need to be released from the concrete. This release of moisture can affect the curing of the mortar and the grout. Many crack-isolation/waterproofing membranes – specifically those membranes that are flat – have limited resistance to pressure from moisture since there is nowhere for the moisture to be released. This in turn creates pressure that can cause the membrane to bubble or debond from the concrete slab. The TCNA Handbook declares that an uncoupling membrane must have free space or empty cavities on the underside of the membrane that inherently allow for moisture/vapor release and eventually equalization. 

The TCNA Handbook prologue uncoupling definition was updated again in 2014 to include: 

“The uncoupling membrane must achieve 50 PSI or greater shear bond strength in 7 days per the test method in ANSI A118.12 Section 5.1.3.”

This addition was in response to the concerns conveyed by labor and some forensic consultants that there were certain so-called “uncoupling membranes” that were failing to the extent of several millions of dollars for repair and damages. The main mode of failure was traced to the bond between the substrate (majority plywood) and the underside of the membrane where the fleece/mesh or other had delaminated. Until an ANSI standard is created for uncoupling, this requirement is a reasonable stop-gap to identify those membranes that are not performing. 

The look of uncoupling has changed over the years but the basic criterion has remained the same: a configured membrane with open-air space to allow for independent movement between the tile and the substrate. Some of the newest additions to the uncoupling category now incorporate a floor warming system and have an optional integrated sound control and thermal break (for quicker heating reaction time).

The need for a standard

Shear testing an uncoupling membrane in the lab using the Instron machine.


The need for an ANSI standard has become more essential in North America than ever before, with the proliferation of new uncoupling membranes that have emerged in the market recently. The good news is that the Materials and Methods Standards Association (MMSA) has had a subcommittee that has been working on developing a standard now for several years. In fact, a draft standard has been prepared and will be presented at the next Total Solutions Plus (TSP) conference this year being held in Nashville, Tenn., October 26 – 29. Those companies, organizations and associations involved in this effort include: ARDEX Americas, Custom Building Products; ISOLA; LATICRETE; MAPEI; NAC Products; The Noble Company; Schluter Systems, LLC; and TCNA. Most of the details in the TCNA Handbook that were identified earlier will be part of the testing criteria. In addition, “Point Loading” and “Fungus/Microorganism Resistance” will be included. Two additional testing criteria under development are vapor transmission and shears to evaluate the stress/strain relationship between uncoupling membranes and other membranes that are flat. This testing has been an international effort that has displayed some promising results.

Uncoupling membrane in a commercial building.


In addition to the MMSA subcommittee working on an uncoupling standard, the International Organization for Standardization (ISO) has established WG 11 “Uncoupling Membranes for Ceramic Tile Installation” under the auspices of TC-189 (Technical Committee for Ceramic Tile). Some of the same participants are in both committees, so there has been very good communication and collaboration to ultimately achieve the best standards for both organizations. Other areas that are being pursued by the ISO group are “tensile” and “compression” testing.

In summary, uncoupling membranes have come a long way since the introduction of the very first membrane in 1987. Use of these membranes has proliferated over a huge array of substrates and conditions, allowing the tile industry to complete successful installations over some of the most challenging applications. The performance standards for uncoupling have been a long time coming, but creating a suitable standard for a product that works more off of physics than chemistry is not an easy or simple task.  

Uncoupling membrane in a commercial building with large format tile.

Standards and specifications for stone products

Photo courtesy of Continental Cut Stone

When is it appropriate to use natural stone on a project? Many of you are familiar with the TCNA Handbook for Ceramic, Glass and Stone Tile Installation that offers many methods, standards and approved installation methods for both tile and stone. 

There are other standards and specifications that A&D professionals as well as tile and stone contractors would do well to consult when clients are considering stone for a job. Following are excerpts from the “Standards and Specifications for Stone Products” document, originally published in the Dimension Stone Design Manual, Version VIII (May 2016), produced and published by the Natural Stone Institute, in
Oberlin, Ohio. 

The document begins by listing all the standards organizations, which will be abbreviated here with phone and URL in the interest of space. 

It then explains the importance of these standards and how and when they apply, as well as an exploration of the function of the organization and the standards that it provides. It ends with a listing of ASTM standards and specifications that are essential references for specific materials, tests and other factors that affect stone

For detailed information on stone, including additional documents on selecting, working with, and installing natural stone, visit the Natural Stone Institute, www.naturalstoneinstitute.org.


1.1 ASTM International 

Telephone: 610.832.9585 


European Office: 

Telephone: 146.243.7933 

1.2 American National Standards Institute (ANSI) 

Telephone: 212.642.4900 


1.3 NSF International 

Telephone: 734.769.8010 


European Office: 

Telephone: 32.2.771.36.54 

1.4 European Commission for Standardization (CEN) 

Telephone: 32.2.550.08.11 


Photo courtesy of TexaStone Quarries


2.1 In today’s building environment, the emphasis is on safe, permanent, low maintenance products, of which stone leads the list in the minds of architects, designers, and consumers worldwide. 

2.2 Without a consistent, realistic set of standards and testing procedures for stone products, the stone industry as a whole would be in disarray. The standards that have been developed and set in place for these products are important tools to help protect end users, individual companies, and the industry from negative effects related to product failures. Materials standards help to prevent the use of stone products for unsuitable applications. For instance, without the minimum standards for Abrasion Resistance of Stone Subjected to Foot Traffic (ASTM C241), it would be more likely that very soft, easily damaged materials would be installed in commercial applications. This may cause the owner to incur additional cost for repair and maintenance, and negatively affect the reputation of the stone industry as a whole. 

2.3 These standards also serve as benchmarks for quality limits of products. If a stone with a below-minimum flexural strength is used for a lintel, then it may be more likely to fail, thus causing damage and possible injury. Interior or exterior flooring or paving with an inadequate slip resistance level will more likely cause slipping accidents in public or private projects. 


3.1 As stone industry professionals, it is our task to apply the correct standards to materials at appropriate times in order to keep the stone industry strong and to remain a reliable source of quality products. 

3.2 Most architectural specifications require that stone meet certain specified ASTM or other testing standards before it will be accepted for use. Some products on the market today have not been tested for quality standards that are required for certain projects. The required testing should be reviewed and, if test results are not available for the stone product, then testing should be performed by the quarry or representative company as required. Some quarries and their representatives do not embrace this idea because their products can be marketed to homeowners and residential projects without the need to perform testing. It is up to our industry to know how to identify these products and make sure to request the required material data needed. 

3.3 Testing of stone can be performed by other companies in the event that required test data are not available. Independent labs can perform the appropriate tests and provide the information in a well organized, professional report. 

3.4 It is important to know when a certain test is not required for a product. For example, a test for Slip Resistance would not be necessary for stone used in a vertical application, which will never receive foot traffic. Some examples are not as easily established. For instance, what are the needs for testing a stone to be used for interior flooring in a commercial application where the stone is installed over a raised floor deck subject to deflection, and will be subject to traffic from pedestrians and cleaning carts weighing 1,000 pounds? It may be required that the stone of choice meets standards related to Slip Resistance, Abrasion Resistance, Absorption, Compressive Strength, and Bending Strength. These are all physical requirements of the stone product during everyday use. 

3.5 Be aware of the requirements of performance that will be placed on the stone at the time of installation, and in the future. If a stone has proven not to perform for a particular use, then avoid marketing it for that use. If testing is not available, require that it be done or avoid the product’s use. 


4.1 The American Society for Testing and Materials International (ASTM), founded in 1898, is a not-for-profit organization that provides a global forum for the development and publication of voluntary consensus standards for materials, products, systems, and services. Over 30,000 individuals from 100 nations are the members of ASTM International, who are producers, users, consumers, and general interest parties such as government representatives and academicians. 

4.2 Committees are established that focus on and have jurisdiction over standards for different designations, such as Dimension Stone (Committee C18) or Cement (Committee C01). These committees are made up of several subcommittees which are tasked to develop and discuss individual segments within the committee’s jurisdiction. For example, one subcommittee may deal with the development of standards dealing with Test Methods of Dimension Stone, and another with Anchorage Components and Systems for Natural Stone. These committees meet on a regular basis to discuss and present information for each new or existing standard. 

4.3 The entire membership of ASTM International votes on whether a standard is suitably developed and researched before it is forwarded for final approval. Negative votes cast during the balloting process are fully resolved before forwarding. 

4.4 Companies, agencies, and individuals use ASTM standards. Buyers and sellers of materials, products, and services include these standards in contracts; engineers, scientists, architects, and designers use them in their work; government agencies reference them in codes and regulations; and many others refer to them for performance information. 

4.5 ASTM International is recognized globally and continues to review and develop new standards needed in a wide range of materials. 

Photo courtesy of Rugo Stone

5.0 ANSI 

5.1 The American National Standards Institute (ANSI), founded in 1918 by five engineering societies and three government agencies, is a private, not-for-profit organization that administers and coordinates U.S. voluntary standards and conformity assessment activities. The Institute represents the interests of its nearly 1,000 company, organization, government agency, institutional, and international members through its office in New York City and its headquarters in Washington, D.C. 

5.2 ANSI currently provides a forum for over 270 ANSI-accredited standards developers representing approximately 200 distinct organizations in the private and public sectors. These groups work cooperatively to develop voluntary national consensus standards and American National Standards (ANS). 

5.3 The ANSI standardization process provides and promotes standards that withstand scrutiny, yet protect the rights and interests of all participants. This process helps quicken the market acceptance of products, while advising how to improve the safety of those products to protect consumers. 

5.4 U.S. standards are promoted internationally by ANSI. The organization also advocates U.S. policy and technical positions in international and regional standards organizations, as well as supporting the acceptance of international standards as U.S. standards where they meet the needs of the user community. 

5.5 The Institute is active internationally with the International Organization for Standardization (ISO), and, via the U.S. National Committee (USNC), the International Electrotechnical Commission (IEC). In many instances, U.S. standards are taken forward to ISO and IEC through ANSI or the USNC, where they are adopted in whole or in part as international standards. 


6.1 NSF International, formerly the National Sanitation Foundation, is a not-for-profit, non-governmental organization that provides standards, certification, education, and risk management services in the fields of public health safety and the environment. NSF was founded in 1944 in response to a need for a single set of food equipment sanitation standards that manufacturers and operators could accept and regulators could adopt into code. NSF has 21 standards for all types of products and materials used in food service. The standards contain requirements for materials, design, construction, and performance of food service equipment to ensure that it is safe and can be kept sanitary. Today, NSF Food Equipment Standards are globally recognized, and certification to the standards is required by regulators, specified by end users, and marketed by manufacturers. 

6.2 NSF Material Requirements – Standard 51. An important component of the NSF Food Equipment Standards is the material requirements. While each standard can have its own unique material requirements, all food equipment standards reference NSF/ANSI Standard 51-2002, Food Equipment Materials. The material requirements help to ensure that only nontoxic and cleanable materials are used. Material suppliers have utilized NSF Certification to Standard 51 as an effective method for marketing their products to food equipment manufacturers. Manufacturers who purchase NSF-certified materials have one less item of concern when getting their own equipment certified. 

6.3 Applying Standard 51 to Natural Stone. When reviewing granite, marble, and other natural stones to the requirements of Standard 51, there are essentially two issues that can determine its acceptance: smoothness and toxicity. 

6.4 Smoothness. The standard defines “smooth” as free of surface imperfections that are detectable by visual or tactile inspection. This includes pits, cracks, and crevices. This concern for smooth surfaces applies not only to the natural surface, but also the treatments used to make a surface smooth. Application of a coating is sometimes considered a way of addressing smoothness; however, coatings have a tendency to chip or flake over time, thus creating their own difficult-to-clean surface. As a result, there is a prohibition on the use of coatings for surfaces subjected to cutting and chopping actions, such as countertops and cutting boards. It is important to note that this prohibition would not necessarily apply to all surface treatments the natural stone industry might use. Sealers that are buffed off to the point where they only remain to fill surface imperfections are not considered a “coating” for the purposes of NSF standards, and could potentially be used on countertops and cutting boards. 

6.5 Toxicity. Standard 51 requires that materials meet FDA regulations for their intended end use, as specified in the Code of Federal Regulations, Title 21 (21 CFR). Applying Standard 51 toxicity requirements to the stone is fairly easy. Because natural stone does not fall under the scope of 21 CFR, we simply conduct extraction testing to verify that the material does not contain any regulated heavy metals. When sealers are used, NSF must have verification from the sealant manufacturer that it meets 21 CFR. An alternative is that the sealant manufacturer can obtain an NSF certification. 

Copies of each standard can be obtained online or by fax from the source. 

Photo courtesy of Delta Stone Products


7.1 Material Specifications 

7.1.1 ASTM C503, Standard Specification for Marble Dimension Stone (Exterior) 

7.1.2 ASTM C568, Standard Specification for Limestone Dimension Stone 

7.1.3 ASTM C615, Standard Specification for Granite Dimension Stone 

7.1.4 ASTM C616, Standard Specification for Quartz-Based Dimension Stone 

7.1.5 ASTM C629, Standard Specification for Slate Dimension Stone 

7.1.6 ASTM C1526, Standard Specification for Serpentine Dimension Stone 

7.1.7 ASTM C1527, Standard Specification for Travertine Dimension Stone 

7.2 Test Standards 

7.2.1 ASTM C97, Standard Test Method for Absorption and Bulk Specific Gravity of Dimension Stone 

7.2.2 ASTM C99, Standard Test Method for Modulus of Rupture of Dimension Stone 

7.2.3 ASTM C120, Standard Test Method of Flexure Testing of Slate (Modulus of Rupture, Modulus of Elasticity) 

7.2.4 ASTM C121, Standard Test Method for Water Absorption of Slate 

7.2.5 ASTM C170, Standard Test Method for Compressive Strength of Dimension Stone 

7.2.6 ASTM C217, Standard Test Method for Weather Resistance of Slate

7.2.7 ASTM C241, Standard Test Method for Abrasion Resistance of Stone Subjected to Foot Traffic 

7.2.8 ASTM C880, Standard Test Method for Flexural Strength of Dimension Stone 

7.2.9 ASTM C1201, Standard Test Method for Structural Performance of Exterior Dimension Stone Cladding Systems by Uniform Static Air Pressure Difference 

7.2.10 ASTM C1352, Standard Test Method for Flexural Modulus of Elasticity of Dimension Stone 

7.2.11 ASTM C1353, Standard Test Method for Abrasion Resistance of Dimension Stone Subjected to Foot Traffic Using a Rotary Platform Abraser 

7.2.12 ASTM C1354, Standard Test Method for Strength of Individual Stone Anchorages in Dimension Stone 

7.3 Other Application Standards 

7.3.1 ASTM Manual Series: MNL 21. Modern Stone Cladding: Design and Installation of Exterior Dimension Stone Systems. 1995. 

7.3.2 ASTM A666, Standard Specification for Annealed or Cold-Worked Austenitic Stainless Steel Sheet, Strip, Plate, and Flat Bar 

7.3.3 ASTM B221, Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes 

7.3.4 ASTM C36/C36M, Standard Specification for Gypsum Wallboard 

7.3.5 ASTM C91, Standard Specification for Masonry Cement 

7.3.6 ASTM C119, Standard Terminology Relating to Dimension Stone 

7.3.7 ASTM C144, Standard Specification for Aggregate for Masonry Mortar 

7.3.8 ASTM C150, Standard Specification for Portland Cement 

7.3.9 ASTM C207, Standard Specification for Hydrated Lime for Masonry Purposes 

7.3.10 ASTM C270, Standard Specification for Mortar for Unit Masonry 

7.3.11 ASTM C482, Standard Test Method for Bond Strength of Ceramic Tile to Portland Cement Paste 

7.3.12 ASTM C630/C630M, Standard Specification for Water-Resistant Gypsum Backer Board 

7.3.13 ASTM C920, Standard Specification for Elastomeric Joint Sealants 

7.3.14 ASTM C1242, Standard Guide for Selection, Design, and Installation of Exterior Dimension Stone Anchors and Anchoring Systems 

7.3.15 ASTM C1515, Standard Guide for Cleaning of Exterior Dimension Stone, Vertical and Horizontal Surfaces, New or Existing 

7.3.16 ASTM C1528, Standard Guide for Selection of Dimension Stone for Exterior Use 

7.3.17 ASTM C1721, Standard Guide for Petrographic Examination of Dimension Stone 

7.3.18 ASTM C1722, Standard Guide for Repair and Restoration of Dimension Stone 

7.3.19 ASTM E72, Standard Test Methods of Conducting Strength Test of Panels for Building Construction 

7.3.20 ASTM E119, Standard Test Methods for Fire Test for Building Construction 

7.3.21 ASTM E575, Standard Practice for Reporting Data from Structural Tests of Building Constructions, Elements, Connections, and Assemblies 

7.4 ANSI Specifications and Standards 

7.4.1 ANSI A10.20, Safety Requirements for Ceramic Tile, Terrazzo and Marble Work 

7.4.2 ANSI A108, Standards for Installation of Ceramic Tile 

7.4.3 ANSI A118, Specifications for Mortars and Grouts 

7.5 NSF/ANSI Specifications and Standards 

7.5.1 NSF/ANSI Standard 51, Food Equipment Materials 

7.6 CEN Specifications and Standards 

7.6.1 CEN specifications and standards are in the process of being compiled. This information will be available at a later date. 

All standards and specifications are revised or updated periodically. The current status of any standard or specification can be confirmed by contacting the proper authority.

Photo courtesy of TAB India

The changing market for ceramic tile in the USA

Donato Grosser’s Coverings presentation looks at the sales patterns for independent distributors

Donato Grosser, principal of D. Grosser and Associates, Ltd.

As part of the conference program at Coverings 19, Donato Grosser, principal of D. Grosser and Associates, Ltd., in New York, offered an analysis of ceramic tile business in the U.S., based on interviews with distributors in Florida, Southern states (Tennessee, Georgia, Alabama, Arkansas, Mississippi, Louisiana, Carolinas), Texas, the Southwest (Arizona, Utah, Nevada, Colorado, New Mexico), California, the Northwest (Oregon, Washington), the Midwest (Ohio, Michigan, Illinois, Wisconsin, Minnesota), New England, New York, New Jersey, and the Middle Atlantic (Maryland, Pennsylvania, Virginia).

The overall findings, targeted to inform independent distributors, show that though there was a strong market increase from 2012 to 2017, a slowdown occurred in 2018. The strength of suppliers like MSI, Emser, Floor & Décor have negatively impacted independent distributor business. Other factors in sales slowdowns are the strengthening of luxury vinyl tile (LVT) and Chinese competition, as well as high cost of installation. The bright spots in Grosser’s report were that remodeling kept distributors in business during the recession, and areas with high birth rates and low taxes and immigration are the strongest economically.

Number of distributors shrinks; big companies get bigger

Grosser’s research shows that although there were 21,725 ceramic tile contractors and dealers in the U.S. in 2008, now that number has plummeted to only 16, 406 in 2018, with a slight swell expected to 16, 806 in 2019. 

These trends run inverse to U.S. ceramic tile consumption, which was at a high of 3,315 million of square feet (m. sq. ft) in 2006, and dropped to only 1,959 m. sq. ft. in 2009. It has slowly increased to an expected 3,170 m. sq. ft. in 2019. Consumption was nearly flat from 2017 at 3,046 m. sq. ft. to 3,107 m. sq. ft. in 2018. 

Overall, Grosser reported that the number of distribution outlets are declining, the number of ceramic tile distributors has fallen from a high of 1,376 in 2014 to a low of 1,241 today. The big are getting bigger and the small are getting smaller, with large distributors expanding and small distributors shrinking. In terms of ceramic tile sales, 2018 was nearly flat, and the growth of LVT as well as flat residential construction will keep sales low in 2019 as well, Grosser predicted. 

Total U.S. manufacturing capacity is now about 1,204 m. sq. ft., with usage of manufacturing capacity at about 80%:

  • Dal-Tile: ~613 m. sq. ft.
  • Italian plants (Stonepeak, Florim, Florida Tile, Del Conca, Landmark): ~430 m. sq. ft.
  • Other main manufacturers: 161 m. sq. ft.

Regional synopsis

Here’s a synopsis of distributor activity according to region. 

Florida – After lows in 2009, sales spiked 60% in 2012-2014, with a 2017 boom for some distributors due to residential and commercial construction. Currently, most sales are for remodeling and commercial construction. Some distributors are exporting to Caribbean islands. Hurricanes turned out to be a mixed bag: sales were lost for a month, but then sales to fix storm damage surged. Negatives include an oil spill in the Panhandle in 2010, Chinese competition, and flat sales from 2017 to 2018 due to competition by Floor & Décor, MSI and Emser.

Southern states – Sales have improved across the South since 2013. In Tennessee, some distributors report a boom; others complain of sales lost to LVT. Sales are up in Georgia, and booming sales in Alabama credit high-end residential and new commercial projects. Arkansas is enjoying a boom; healthy sales in Mississippi and Louisiana are up 10-15%, and sales in the Carolinas are flat to 15% up. 

Texas Though there was a slowdown at the end of 2018 – which some companies attributed to the mid-term elections – many companies have reported sales gains of 15-20% per year since 2014. Commercial construction, hospitality and remodeling are abundant; sales are surging in Houston due to remodeling after hurricanes. 

Southwest – New construction in residential, hospitality and restaurants is contributing to 20-30% boom conditions in parts of Arizona, especially in Phoenix. Utah is seeing sales rise 7-20% due to rise in multi-unit residential projects, mid-to-high-end residential and commercial construction. 2018 sales are up in Nevada 10-20% due to new construction and residential remodeling, though LVT is impacting tile sales as builders embrace LVT. Colorado is reporting sales increases across the board, especially in the Denver area and suburbs where high-end residential construction and new commercial construction are going strong. In New Mexico, one distributor reported 10% sales gains last year due to mid-to-high-end residential construction and new retail and hospitality construction; another distributor said he was impacted by loss of government money in the region. New construction is strong for healthcare projects.

California – The Golden State has enjoyed steady growth from 2010 to 2018, though the rate has slowed in the last six months. Bright spots are growing sales in tile slabs, large importers selling to tract housing developers and small and medium distributors supplying remodeling efforts. The interest in low-cost Chinese tile is being felt in this state. 

Midwest – After sales bottomed out in 2008-2009, Ohio distributors saw sales surge up to 20% 2013-2016, mostly for residential remodeling. Last year sales were up for commercial projects, retail, institutional and offices. Michigan saw similar growth over those years due to new hospitality and office construction, and high-and-mid-level residential, with 60% sales due to remodeling. 2018 saw a slight slowdown. Illinois saw 15-20% growth per year 2012-2018 in residential remodeling or multi-unit construction until a slowdown in 2018. Post-tornado sales in 2015 soared. Tiles are mainly used in bathrooms and some kitchens, fighting competition from wood flooring. Wisconsin is a mixed bag with some reports of booming 30% sales increases from 2017 due to high-end residential, remodeling and new commercial building; others saw sales are down due to competition from VCT and LVT. Minnesota distributors saw yearly increases of 10-20% from 2012-2016; in 2018, some reported 10% hikes, while others said installation costs are negatively impacting tile sales and one distributor said sales fell 20% due to customers switching to LVT. 

Northwest – Sales in Oregon last year spiked 5-15%, with residential construction doing well; some distributors reveal that remodeling makes up 50% of sales. In Washington, recovery began in 2013; between 2016-2018 new high-end residential and retail projects pumped up sales 10% each year. 

New England Sales were mostly flat for 2018, declining in the second half of the year. New high-end residential and commercial fueled sales, but some distributors say companies are leaving Connecticut due to high taxes and the recently-instituted $10,000 cap on state and local taxes (SALT) that taxpayers can claim on their federal income taxes. 

New York – Though sales surged in the wake of Hurricane Sandy, 2018 was mostly flat in the area, except in high-end Manhattan apartments and suburban areas with high birth rates that spurred residential remodeling. Big-box competition, internet sales, and exodus of people to the South and West are depressing sales in the region. 

New Jersey – 2018 was stellar for many companies, though sales fell after August and some companies are reporting flat sales, depressed by competition from Floor & Décor and similar stores and high installation costs that spurred a switch over to LVT products. Sales health was found in new commercial building and residential remodeling.

Mid-AtlanticSales were down or flat in Virginia and Pennsylvania (except for an increase from 2011 to 2018 in Pittsburgh); Maryland is expecting an increase in the first quarter with most companies reporting 5-15% increase due to healthy mid-to-high-end residential and commercial, except in areas where construction is down. 

Is there anything in writing regarding use of red body ceramic tiles as shower floors?


Image courtesy of Bedrosians Tile & Stone.

Is there anything in writing you can provide regarding use of red body ceramic tiles as shower floors? I generally don’t recommend high water-absorption products in showers. I realize the glazes are impervious, but I have seen failures when the body of the tile has a high water absorption >7% and in some cases >10%. Is this addressed anywhere in the NTCA guide either for or against it?


I discussed this with several members of our technical team. As you and I also discussed on the phone, we are not aware of any item in the industry standards, including ANSI A137.1, ANSI A108, the methods and best practices found in the TCNA Handbook or the NTCA Reference Manual that describe whether it may be acceptable to install a red-bodied ceramic tile in a wet area such as a shower floor.

The best basis we have to go on is whether this is a floor tile and whether the manufacturer recommends it for installation on floors in wet areas.

Also, it may be important to consider whether the type of shower pan this entry-level-option shower floor tile will be installed on is water-in / water-out (thick-bed system with a liner and pre-slope i.e TCNA Handbook Method B-415) or if the tile will be installed on top of a sloped pan with a surface-applied membrane. If it will be installed on top of a surface-applied membrane, it is important to
consider whether the draining water may be absorbed by the body of the tile as it percolates through the grout and into the bond coat and body of the tile as it makes its way to the surface-applied waterproofing layer. I do not know for certain if this will lead to an issue with bond or performance of the tile or of the system.

I ran your question past a Recognized Consultant for a quick opinion. Here is the slightly paraphrased answer: “In a perfect world, it would work, but I wouldn’t do it. Soft absorbent body, unforgiving of installation error, glazed surface. I don’t see any cost savings. Why not a cheap porcelain? Wet is one thing; soaking absorbent tile in soapy water is another.” 

– Mark Heinlein,
NTCA Training Director

Needing information about certification for thin porcelain slabs


I’m a tile contractor, and need information about certification for thin porcelain slabs. Please
contact me.


Please visit our website to view the locations we have scheduled for GPTP training in 2019.

Please note that some of the programs listed at this link are Substrate Prep / LFT classes. The GPTP classes are scheduled for:

  • Louisville, KY
  • Plymouth, MN
  • Denver, CO
  • Bethany, CT
  • Seattle, WA
  • Norcross, GA

Since these courses are in high demand, I suggest registering early. There is no fee to attend these classes, however $50.00 is charged at registration to hold your seat. The $50 is refunded when you attend. 

– Mark Heinlein,
NTCA Training Director

NTCA Five-Star friendships lay groundwork for business partnership

There are many benefits to being a contractor member of NTCA. If you are wondering what they are, take a look at the May TileLetter Benefits Box to see them all in one fell swoop.

There are additional paybacks to being one of the elite contractor members known as NTCA Five-Star Contractors. This group has a rigorous set of requirements to join, but enjoys special perks such as manufacturer discounts, special regional training opportunities and attendance at the annual NTCA Five-Star Summer meeting. At the summer meeting they are privy to top-notch speakers, presentations and demos on technical and business aspects of their business, and ample chance to network with fellow Five-Stars to share best practices. 

Dan Welch, Welch Tile & Marble

Sometimes, partnerships grow out of membership in this network of high-caliber contractors. A joint venture between Welch Tile & Marble Co., in Kent City, Mich., and Kemna Tile in Dallas, Texas, is one such partnership that owes its beginnings to a Five-Star connection. 

Working together

Dan Welch of Welch Tile & Marble and Barry Kemna of Kemna Tile worked together before they became NTCA Five-Star Contractor members, spurred by the need to diversify in light of the 2008 downturn. In the tradition of NTCA members helping each other, Welch Tile – at the time a labor-only company – received a hand from full-service contractor Kemna Tile, both of whom were NTCA board members at the time, about 2010. 

Barry Kemna,
Kemna Tile

“The relationship blossomed since we were sharing labor,” Welch said. “We took a lot of risks together. Now we are team building.” Before Kemna developed its own terrazzo team, there was a lot of terrazzo work across the country with clients Kemna had relationships with, and Welch was able to joint-venture with an experienced crew.

Over the years, Welch grew into a full-service company and in 2017, “sold more work than we could do,” Welch said. Kemna came to Welch’s aid on the Klondike Cheese plant project in Monroe, Wis., and terrazzo projects Travers City East Elementary and Mercy Hospital in Muskegon, Mich. “Roles go back and forth, based on workload,” Welch said. 

Working on projects like the Duke Cancer Center in Durham, N.C., Portneuf Medical Center in Pocatello, Idaho, Seton Medical in Killeen, Texas, the Federal Building in Tuscaloosa, Ala., and the Faena Forum Event Center in Miami spawned a learning friendship, in which each company learned how each others’ team operates. 

“In Miami, the project scope expanded,” Welch explained. “Welch shipped a terrazzo grinder down. It helped him to not have to put out $30,000 for a grinder, and it helped us get the job. We pool our labor forces, equipment and people,” he added, shipping equipment to or from Texas and Michigan where needed.

Kemna remarked, “We are both working on projects out of town, having the confidence to know Dan will send folks if we get behind. That gives us confidence to bid; we have another resource to call on for labor.”

At times, the company has pulled in other NTCA Five-Star Contractors to assist; for instance, Neuse Tile Service in Youngsville, N.C., did all the tile work on the Duke Cancer Center, and Collins Tile and Stone in Ashburn, Va., partnered on a D.C. project. 

The arrangement offers tremendous flexibility, offering both companies opportunities to take jobs they wouldn’t be able to complete on their own. Plus, they are pooling their expertise to make better business decisions, touching base once or twice a week. “Between the two of us, 150 people are at stake,” Kemna said. 

The Duke Cancer Center in Durham, N.C., was one of the first projects that Welch Tile & Marble and Kemna Tile partnered on. Not shown here is tilework installed on this project by another NTCA Five-Star Contractor: Neuse Tile Service.

The NTCA Five-Star connection

Amber Fox, NTCA Five-Star Program Director

The NTCA and caliber of the NTCA Five-Star Contractor community laid the groundwork for this relationship to blossom. “We come together at meetings as part of a bigger group, and there’s an opportunity to have growth,” said Amber Fox, NTCA Five-Star Contractor Program Director. “The NTCA Five-Star Program is the catalyst of bringing people together and providing opportunities.”

“NTCA Five-Star is an opportunity to start relationships so things can happen in the future,” Welch said. “If you are going to take on that big a risk, you need someone you can trust. Without NTCA or NTCA Five-Star – or both – we would never have gotten to that level to take on that risk.” Plus, Welch added, “If you enjoy each other, it makes it easier to do.”

“NTCA Five-Star has allowed us to make our businesses stronger,” Kemna added. 

At the upcoming NTCA Five-Star Summer Meeting July 16-19 in Montreal, Fox will offer non-competing contractors who are interested in exploring joint venture possibilities the opportunity to process issues together to open the door for reciprocal communication and relationship building. Depending on feedback, follow-up opportunities will be planned. 

“Due to relationship with Dan, it’s given more opportunity,” Kemna said, pointing out that the synergy between the two companies has provided a buffer against competition. 

“We are NTCA Five-Star contractors that do tile, but businesses have grown and incorporate other things,” Kemna added. “Carpet contractors started taking work away from us by being able to do carpet and adding tile. Now I see because we are doing terrazzo, polished concrete, stone panels, thin panels and tile, we are the biggest piece to put under contract. If we ONLY did tile, it would be easy for carpet guys to take it over.”

Welch said that his partnership with Kemna helps manage schedules and the fluctuations of the economy. “You surround yourself with people who have strengths where you are weak,” he said. “Change is inevitable – managing it is everything.” 


For more information on becoming a NTCA Five-Star Contractor, contact Amber Fox at 858-674-6908 or at [email protected].

Tile over elevated deck with uneven concrete slab


I have an outdoor elevated deck approximately 300 sq. ft.

We removed the existing ceramic tile to reveal a very rough and uneven aggregate concrete slab. This slab also seems to have sunk in the middle a bit. 

The client wants us to waterproof with a waterproofing membrane system including a liquid-applied membrane, and then install porcelain tiles about 3/8” thick. 

Since the slab is pitched away from the house and is not level, should we try using self-leveling material? Skim coat? Apply the membrane and tile all in one step?  

Please advise. Thank you!


Exterior decks, especially those over occupied spaces, are very prone to failure and must be constructed correctly.

As you noted, the first concern on this project is the suitability of the concrete substrate. It sounds like the existing slab may be a candidate for repair with an appropriate topping coat or possibly with deck mud. But your description of its overall condition and that it has sunken in the middle might indicate that the original slab pour might not have been done correctly and the supporting structure may not have been able to properly support it. These existing conditions would translate into trouble when it comes to supporting the new tile system installation.

It is critical that any exterior tile installation, especially those attached to buildings, be sloped or pitched away from the building. The pitch must be at least 1/4” vertical fall for every 12” horizontal run. You want to make the planes to be tiled flat, but you would not want to make them level by placing a self leveler or any patch materials.

IF all of the supporting structure is correct and adequate and IF the slab is sufficient to support the new installation, then the deck system can be considered. TCNA Handbook Methods 103B and 104B would most accurately reflect the details required for the situation you are looking at. Please take a look at these in your Handbook and review them closely. Supporting structure, pitch away from the structure, waterproofing membranes, proper flashing to the structure, water runoff management systems, etc. are some of the critical points that must be considered.

It sounds like this may be a situation where the existing concrete should be removed and the supporting structure carefully analyzed. A method such as F105 could then be considered as a possibility for this installation.

The freeze-thaw environment in New York is an extremely important consideration for any exterior installation. Proper placement and construction of movement joints (and again, water drainage) is absolutely critical for the performance of the system. Even with proper materials, ongoing routing maintenance of the movement joints will be necessary.

There are far too many details to discuss in this email. Please take a look at the methods I’ve mentioned and compare them to the existing installation and what it will take to make the new installation conform to the methods.

Some material manufacturers make drainage mat systems that work well to manage the water flow and support the tile installation. After reading the methods and considering the points I’ve described please email back and let me know what approach you think might work best, and I can try to help you answer any questions you might still have. I hope this helps! 

– Mark Heinlein, 

NTCA Training Director

Large sizes reign at Coverings ’19

Technology enhances surfaces, realism

Though any good tile exhibition will present a range of product from the tiniest mosaic to sprawling slabs, Coverings ’19 was rife with products that ran 12 x 24 and larger. The new “standard” popular size is now 12 x 24 in fact, but we’re seeing a range of 24 x 48, 28 x 48 and larger formats coming into vogue. 

Digital printing techniques get more and more sophisticated, with “sinking ink” applications that allow the decoration to penetrate into crevices, veining, nooks and crannies, producing an even more authentic appearance. 

Following is a range of products that celebrate the new large sizes, slab product or setting materials that are necessary to create an installation as beautiful and durable as the products themselves. 

Cotto D’Este’s Kerlite Wonderwall

Cotto D’Este – The company’s 3.5mm Kerlite Wonderwall line offers digitally printed graphics on rectified porcelain that measures 39 x 39 up to 30 x 118 slabs. A range of graphics from flowers to forests to jungles (pictured) to gentle geometric designs and more are available. 

Milestone’s Onyx

Milestone’s Onyx comes in matte and polish in five colors and 12 x 24, 24 x 24 and 24 x 48 rectified color body porcelain. The High Definition Graphic imparts a sense of depth that is rare in matte products. With 40% recycled content, this Italian tile is made in the USA in Clarksville, Tenn. 

Vitromex’s Barque

Vitromex – Made of Vitromex’s red-body CeraCore+ ceramic body in a new 7 x 40 plank format, Barque gets its inspiration from the rough, weathered wooden planks of a ship (“barque” in Spanish). In Chestnut Brown and Ember Grey (pictured), the planks have a range of variation within the box for a highly natural effect. 

Vives Resort

Vives – The Resort collection features a wide range of nominal designs and patterns and sizes. The Nikoi series comes in nominal 48 x 48 and 8 x 48 rectified formats.

257 Titanium

LATICRETE – 257 Titanium is the ultimate, lightweight one-step, polymer fortified, thin-set mortar that is ideal for the installation of gauged porcelain tile panels/slabs (GPTP) as well as for interior and exterior installation of ceramic tile, porcelain tile, stone, quarry tile, pavers and brick. Plus, it is free from silica sand. 

Ariana Epoque

Ariana – Epoque in the Ariana brand offers stunning effects in six marble varieties and five sizes including 12 x 24, 24 x 24 and 24 x 48. All sizes come in natural finish and the two largest sizes also are available in lappato/honed. 

Marazzi Merona

Marazzi’s Merona features a new 8 x 40 plank format in four colors with Stepwise anti-slip technology. It’s shown with Basalto on the fireplace surround, which comes in large sizes up to 24 x 48. 

Rubi Slim Tile Cutting System

Rubi Tools – Manufactured in Barcelona, Spain, the Rubi Slim System offers a scoring rail, sturdy table and nippers for work with large-format tile and gauged porcelain tiles. It’s designed specially for porcelain tiles on the market of up to 9.84 ft by 3.94 ft and between about 1/8” and 3/8” thick.

The set consists of: three 43.30” aluminium guides, one scoring wheel with a Ø 7/8” tungsten carbide roller guide, two breaking pliers, two suction pads and a reinforced nylon carrying case.

American Olean Ideology

American Olean – Ideology, a new stone look-alike porcelain, comes in 24 x 48, 24 x 24, the ever-popular 12 x 24, 4 x 12 planks, herringbone accent and 24 x 24 black and white polished decorative accent. Shown is Carrera marble; it also comes in vein-cut Calacatta and Lasa.

Miracle Sealants’ Levolution

Miracle Sealants – Recently purchased by Rustoleum, Miracle Sealants’ Levolution lippage control system has a reusable cap that applies pressure to all four tiles that meet at a corner. The adaptable profile can be broken off and customized to the needs of the installer. 

Onice Malaga

Iris A stunning example of the power of large slabs was the Iris booth that featured 120 cm x 60 cm (nominal 48 x 24) Onice Malaga gauged porcelain tile panels in a mesmerizing display of cuts and angles. 

Leonardo Overcome

Leonardo – Overcome is a new 48 x 48 terrazzo-look full-body porcelain. It features a digital dry decorating technique. Available in 24 x 48, 24 x 24 and 12 x 24. 

Inalco Senda

Inalco – Senda, in the SLIMMKER line, features grey brushstrokes of color on a gentle stone-like relief texture porcelain tile. Delicate, versatile and with a magnetic appeal in 6mm thickness, sizes range from nominal 40 x 40, 40 x 99, 60 x 60 and 60 x 118.

Florida Tile Modtique

Florida Tile – Modtique
HDP color body rectified porcelain floor and wall tile comes in three colors in 8 x 48 planks and 12 x 24, 24, x 24 and 24 x 48 formats. This U.S.-made tile is inspired by European Antique stones in modern colors. 

Crossville Alaska

Crossville – Large-format Alaska has a matte terrazzo look with a shimmering fleck that adds interest and depth. The line has five versatile colors ranging from light to dark in 24 x 48, 24 x 24, and 12 x 24 field formats, with two mosaic options, bullnose and cove base trims. Alaska will be released later this year.

American Wonder Porcelain Avaro

American Wonder Porcelain – U.S- made Avaro porcelain planks come in 6 x 48 and 8 x 48 lengths in Dove Grey, Natural Beige and Dark Timber. The factory also offers Asher porcelain in matte and lappato in 8 x 48, 12 x 28, 12 x 24, and 24 x 48. Asher has Traction Enhance Technology which actually increases the DCOF when water is applied.

Overreliance on spacers leads to consumer complaints

Does lack of willingness to purchase installation excellence exclude tile setters who craft quality work?

Coverings is not only an opportunity to see firsthand the latest tile and stone styles and trends; it’s an opportunity to learn about the latest technical and installation challenges and the efforts underway to address them. One such discussion at this year’s show last month was the premise that an increasing number of installers are not using measurements and chalk lines to square up and lay out their tile installations. Instead, they are relying on hard spacers, usually made of plastic, to determine the grout joint width and tile positioning, which can result in misaligned tiles.

Contrasting grout and tile make misalignment more obvious than less-contrasting grout and tile.

Contrasting grout and tile make misalignment more obvious than less-contrasting grout and tile.

NTCA requested this topic be included on the agenda for the ANSI ASC A108 Committee meeting held at the show. The discussion was initiated by NTCA Board member and Technical Committee Chairperson James Woelfel, who is active in development of installer and contractor best practices through involvement in and leadership of numerous technical committees. Reliance on spacers has become a critical issue, according to Woelfel, who, in addition to contracting, is engaged in inspection and consulting. He says this problem is the cause of about 80% of the inspections he has performed so far in 2019.

The committee discussed the well-understood and accepted function of the grout joint as the necessary adjustable component of every tile installation that accommodates variations in tile sizing, an inherent characteristic of tile. But hard spacers inhibit that adjustability factor. Accordingly, the less consistently-sized a tile is, the greater the misalignment that will be caused by hard spacers because of the greater need to adjust the grout joint for the tile size differences. 

ANSI A137.1

Rectified tile has less size variation, stipulated by ANSI A137.1, compared to calibrated tile, for which more size variation is allowed.

Conversely, the problem that Woelfel believes is on the rise would be less pronounced with rectified tile. This is because of the very small amount of size variation allowed for rectified tile, per ANSI A137.1, as compared to tile classified as calibrated tile, which is allowed more variation. 

Tile classified as “natural” has very intentional size variation for aesthetic purposes and is allowed the greatest amount, and many tiles have even greater intentional variation and fall outside the tile standard completely. 

But spacers themselves aren’t the enemy. They can be combined, or adjustable varieties can be used, to produce a good end result even when there is significant size variation in the tile. 

Exploring the cause of the issue 

The root cause of the issue is debatable. Perhaps there is a lack of awareness of size variation and how to deal with it, and a lack of qualified installers despite the availability of information and instruction available, especially online. Or, perhaps installers know better, but are working at rates that unquestionably require speed over precision. Is there a lack of willingness by homeowners and GCs to “purchase” installation excellence that excludes those who would take the time and make the effort to make aesthetic adjustments?

Spacers used in combination to give tile with purposeful size variation a consistent overall appearance.

Spacers used in combination to give tile with purposeful size variation a consistent overall appearance.

One can only speculate. Most inspection reports address only whether an installation does or does not meet industry standards. When it does not, the common presumption is that installer error is wholly to blame. But a deeper-diving, less black-and-white assessment might reveal significant culpability of homeowners and GCs choosing not to hire qualified labor. 

It’s an important question for the industry. Perhaps Woelfel’s spacer-related observations are a microcosm. Does an increase in improper spacer use signal worsening undervaluation of craftworkers and trade work? We should try to find out. 

Some installers use compressible materials like rope to space tile.

Some installers use compressible materials like rope to space tile.

If misaligned tile due to spacer use reflects a shrinking willingness to purchase trade excellence, could we trace the lack of qualified labor back to that lack of demand? Could it be considered a labor market correction, i.e., a generalized lowering of output quality that equalizes the supply side with the demand side? 

It may sound controversial but does the opposing theory make sense? Is it possible that the tile-consuming public not only wants  – but is generally willing to purchase excellence – yet contractors and installers are either disinclined or unable to find a way to meet that demand despite the profitability of doing so? If that were true, contractors that do deliver quality work would have an almost unmanageable backlog of work, while subpar contractors would get very little work and be virtually driven out. Unfortunately, it seems the opposite is the case: quality contractors often struggle to get work, and report that the projects they bid on are routinely awarded to contractors that do not provide the same level of installation quality.

Determining precise layouts

Whatever the reason for it, the implications aren’t limited to some misaligned tiles. Even if all the tiles on a job were miraculously the exact same size, with zero adjustability needed, Woelfel’s observations still signal a problem.

The method of using measurements and chalk lines to lay out an installation is the skill that enables the tile installation to be oriented in the best way possible for a given tile and pattern in a given space. Laying out tile is the process of determining the size and placement of cuts (partial tiles) before any tile is set. Especially for larger installations, it’s a decision-making process, which may even involve a home or building owner since the “best layout” is often subjective.

One homeowner might want full tile at a certain threshold or transition to other flooring, regardless of how that arrangement decision impacts the tiles on the opposite side of the room; while another individual would prefer a more centered design. 

Tiling the main aisles of a furniture showroom requires precise layout to ensure tile rows are aligned on center with columns.

Tiling the main aisles of a furniture showroom requires precise layout to ensure tile rows are aligned on center with columns.

Only through professional layout processes can the layout options, including the aesthetic pros and cons of each option, be known and evaluated and an informed decision be made. Similarly, the professional layout process enables installers to adjust a layout to meet specific points and locations as needed in-situ. Installers may have to ever-so-slightly expand or compress a layout in order to “make it work,” imperceptibly, and over the course of multiple rows.

Several ANSI Committee members said they support Woelfel’s thinking that language could be added to ANSI standards and/or the TCNA Handbook relating to the potential for spacers to result in misaligned tiles. As part of the related awareness efforts, the larger implications should be emphasized. The idea is to not only avoid crooked tiles due to spacers, but to ensure that the highest level of craftsmanship is available wherever and whenever needed. This is not accomplished by seeking out qualified installers and companies only for the most critical projects, but rather by helping to sustain them by being their regular partner on the jobs in between. 

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