Durability of Tile Assemblies

Ceramic tile is a durable material able to withstand heavy loads, high impact, and the wear that comes with decades of continual use. In recent years, competing materials like LVT have emerged, making bold claims of durability and longevity. This raises questions like what does it mean to be durable, and can durability be quantified? This article will shed light on exactly what a durable assembly is, how durability is measured, and how the tile industry supports its claims of durability.

Factors affecting performance?

Dozens of factors contribute to the performance and durability of a tile assembly. These factors can be categorized by the variability of materials, methods, and applications. To predict performance, we must understand what is being installed, how it is being installed, and where it will be used. Who the installers are is also an important consideration.?

What is being installed? ?

The many choices of tiles and other materials in the assembly present the first set of variables that impact performance. Even within ANSI A137.1, there are different performance characteristics for different types of tile. The same is true for the variety of setting materials and grouts that may be used. Varying substrates have vastly different properties which impact the performance of the tile assembly.?

The initial measure of performance for a tile assembly is the durability of the tiles themselves. ANSI A137.1 and the various ASTM and ISO tests it references have clearly defined criteria for abrasion resistance, breaking strength, bond strength, thermal shock, freeze/thaw cycling, and impact resistance. All these factors contribute to the overall durability of the tile, which is the first line of defense for the assembly. A good quality tile in compliance with ANSI A137.1 won’t guarantee a durable assembly, but it’s a very good start!

How is it being installed??

Installation methods are the second set of variables that impact performance. As important as it is to have durable tiles, it is also imperative that the tile and everything behind it function together as a durable assembly. Let’s look at how tile assemblies are described in the TCNA Handbook using a system of performance levels. Performance levels, also known as performance ratings or service ratings, are classifications of the assembly that indicate how well it will perform - in other words, how durable it will be. There are five service rating designations for tile floor assemblies in the TCNA Handbook, each correlating to a category of use based on the types of loads expected:?

Extra Heavy is the service rating for extra heavy and high-impact use in food plants, dairies, breweries, and kitchens. It requires quarry tile, packing house tile, or tile designated by the tile manufacturer for the intended application.?

Heavy is the service rating for shopping malls, stores, commercial kitchens, work areas, laboratories, auto showrooms, and service areas, shipping/receiving areas, and exterior decks.

Moderate is the service rating for normal commercial and light institutional use in public spaces of restaurants and hospitals.?

Light is the service rating for light commercial use in office spaces, reception areas, kitchens, and bathrooms.?

Residential is the service rating for residential kitchens, bathrooms, and foyers.?

Every floor tile installation method appearing in the TCNA Handbook falls within one of these performance ratings. For example, method F122 Interior floor thin-bed method over on-ground concrete with waterproof membrane is classified as having a Moderate service rating. The service ratings are found in the TCNA Handbook’s Floor Tiling Installation Guide section as well as in the methods themselves.?

The service rating designated for each method does not exceed the performance of the weakest component in the respective method. For example, depending on its density and thickness, the presence of a membrane may adversely affect the service rating of an assembly.?

Readers of the Handbook’s Floor Tiling Installation Guide are instructed to first determine the required performance level of the assembly, and then choose the installation method that meets or exceeds the desired performance. For example, if the project is a retail store, the required service rating is Heavy, and therefore it should use method F103, F103B, F104, or F121. Additionally, any method classified as Extra Heavy would also be acceptable. Methods designated with Moderate, Light, or Residential service ratings would not be acceptable for a retail store.

Installations subjected to heavy loads like automobile dealerships should use a tile assembly with a performance service rating of at least Heavy, which means the tested assembly has passed at a minimum of cycles 1 through 12 of the Robinson Floor Test. Photo courtesy of Crossville, Inc.

Evaluation of Floor Systems?

Now that we know that service ratings are key indicators of a tile assembly’s performance, let’s look at the science behind these designations. The five performance levels recognized in the TCNA Handbook are based on ASTM C627, commonly known as the Robinson Floor Test.?

The Standard Test Method for Evaluating Ceramic Floor Tile Installation Systems Using the Robinson-Type Floor Tester, ASTM C627, has been used by the tile industry since 1970, and is widely acknowledged as a reliable predictor of a floor’s performance under several dynamic loading conditions.?

According to ASTM C627, this test method provides a standardized procedure for evaluating performance of ceramic floor tile installations under conditions similar to specific real-world usages. It is intended to evaluate complete ceramic floor tile installation systems for failure under dynamic loads. The method can test a variety of substrates including concrete and wood, various underlayments and membranes, and various installation methods and setting materials.?

The Robinson Floor Testing Machine uses a three-wheeled cart that rotates about its center on top of a section of a tile floor assembly to be tested. The cart’s wheels are attached to swivel casters and are configured as an equilateral triangle. There is a vertical rod above each wheel that accommodates weights of up to 300 pounds per wheel, which are stacked in increasing increments during the test. A 3/4-horsepower motor drives the assembly, and the cart rotates at a rate of 15 revolutions per minute creating a wheel path 30 inches in diameter along the tile floor.?

In the Robinson Floor Test, a weighted three-wheeled cart travels over a tile assembly in a 30 in. diameter circular path at a rate of 15 revolutions per minute for 30 to 60 minutes per cycle, for up to 14 cycles, with loads increasing from 300 to 900 pounds and wheel hardness increasing from soft rubber to hard rubber to steel from cycle to cycle. The assembly is assessed for damage after each cycle.

The Robinson Machine tests the assembly to failure over the course of up to fourteen cycles of cart travel, using heavier loads and/or harder wheels with each successive cycle. Damage is assessed after the completion of each cycle. Cycles 1 through 4 use soft rubber wheels and are 60 minutes in duration with weights of 100-300 pounds over each wheel. If the assembly has not yet failed, cycles 5 through 8 use hard rubber wheels and are also 60 minutes long with 100-300 pounds over each wheel. If the assembly has continued to survive, cycles 9 through 14 use steel wheels and are 30 minutes long with weights of 50-300 pounds over each wheel. Damage is quantified as chipped tile, broken tile, loose tile, spalled grout joint, cracked grout joint, or powdered grout joint. ASTM C627 includes clear guidelines on how to quantify the damage to the tile and grout joints in the wheel path, and how much damage constitutes failure of the test. However, the standard does not interpret the test results; that is done in the TCNA Handbook.?

The Handbook’s Floor Tiling Installation Guide establishes a correlation between a method’s Robinson Floor Test result and its service rating. Assemblies passing cycles 1 through 3 are rated Residential. Assemblies passing cycles 1 through 6 are rated Light. Assemblies passing cycles 1 through 10 are rated Moderate. Assemblies passing cycles 1 through 12 are rated heavy. And assemblies passing cycles 1 through 14 are rated Extra Heavy. Every floor method in the Handbook has undergone the Robinson Floor Test and has been assigned a service rating based on the results. ?

Where is it being installed??

Where the tile assembly is installed in terms of exposure to environmental factors present the third set of variables that impact performance. For example, tile assemblies in wet areas or exposed to direct sunlight will perform differently than interior dry assemblies and must be designed and installed for resistance to moisture, humidity, and heat. The exposure of a tile assembly impacts its durability.?

The TCNA Handbook lists six categories of use for residential installations and seven categories for commercial installations, collectively known as Environmental Exposure Classifications. A shortened version of this list appears below. To distinguish between commercial and residential, commercial applications are generally more demanding of the assembly, and commercial cleaning and maintenance practices typically generate greater water exposure than residential practices. The environmental exposure classifications consider the assembly’s proximity to moisture, humidity, and temperature:?

Com1 (Commercial Dry): Tile surfaces that will not be exposed to moisture or liquid except for cleaning purposes. Examples include floors in areas with no direct access to the outdoors and no wet utility function such as hallways, dry area ceilings, accent walls, and corridor walls.?

Com2 (Commercial Limited Water Exposure): ?Tile surfaces that are subjected to moisture or liquids but do not become soaked or saturated. Examples include floors where water exposure is limited and/or water is removed, as in bathrooms and locker rooms. Some backsplashes, bathroom walls, other walls, and wainscots may also fall in this category.?

Com3 (Commercial Wet): Tile surfaces that are soaked, saturated, or regularly and frequently subjected to moisture or liquids. Examples include shower and tub floors and walls, enclosed pool areas, natatoriums, public communal showers, and some commercial kitchen floors and walls.?

Com4 (Commercial High Humidity, Heavy Moisture Exposure): Tile surfaces that are subject to continuous high humidity or heavy moisture exposure, especially in enclosed areas. Examples include continuous use steam showers and steam room walls and ceilings.?

Com5 (Commercial High Temperature ≥125°F): Tile surfaces frequently subjected to water or vapor greater than or equal to 125°F. Examples include commercial saunas, furnace and boiler areas, and some commercial kitchen floors and walls.?

Com6 (Commercial Exterior): Tile surfaces exposed to exterior conditions. Examples include exterior walls, balconies, and decks.?

Com7 (Commercial Submerged): Tile surfaces exposed to continuous water submersion in interior or exterior conditions. Examples include swimming pools, water features, and fountains.?

Every installation method appearing in the TCNA Handbook has been assigned one or more environmental exposure classification, indicating that the method is expected to perform well in those exposures. For example, method F122 Interior floor thin-bed method over on-ground concrete with waterproof membrane is rated as Res1/Com1, Res2/Com2, Res3/Com3, and Res4/Com5. The classifications are found in the TCNA Handbook’s Environmental Exposure Classification section as well as in the methods themselves.?

Unlike the service rating categories which are connected to ASTM C627, the environmental exposure classifications are not tied to any test, rather they are based on the tile industry’s assessments of different assemblies that have proven to be durable in harsh environments.?

When selecting an installation method, design professionals are urged to consider the assembly’s exposure to moisture, humidity, and extreme temperatures; and for exterior applications, to consider local climate and conditions including temperature, temperature fluctuations, humidity, humidity fluctuations, and freeze/thaw cycling. If waterproofing is desired, it must be specified.

Tile in areas that are soaked, saturated, or regularly and frequently subjected to moisture, like residential showers, should use an installation method having environmental exposure classification of Res3 (Residential Wet) or Com3 (Commercial Wet).

Who is it being installed by? ?

So far, we have examined the contributions to durability made by good material selection, appropriate installation methods, and consideration of environmental exposure. Even if all these boxes are checked, if qualified labor is not used to install it, the assembly may still fail over time. Fortunately, the tile industry has well-established benchmarks to help identify tile contractors and installers with the qualifications necessary to provide durable and long-lasting installations. TCAA’s Trowel of Excellence certification distinguishes best practice tile contractors who are signatory with the International Union of Bricklayers and Allied Craftworker (BAC). The International Masonry Industry Training and Education Foundation (IMTEF) delivers comprehensive tile training for pre-apprentice, apprentice, and journeyworker tile setters and finishers. Installers who hold an Advanced Certifications for Tile Installers (ACT) certification have demonstrated outstanding technical efficiency. Requirements for minimum levels of competence can be written into a project’s specifications to ensure appropriate installation.?

Durability validated?

Because durable finishes are desirable, claims of durability are widespread among suppliers of building materials and systems. Terms like “durable” are relative, subjective, and difficult to define. However, the tile industry has developed and implemented sophisticated mechanisms to define and measure many of the criteria of durability. Material standards like ANSI A137.1 put forth requirements for strength, abrasion resistance, and other qualities of durability that can be measured. Tests like the Robinson Floor Test simulate real installations under real loads and provide accurate predictions of performance. Classifications such as performance ratings and environmental exposures consider the ability of tile assemblies to perform under loads and resist extreme exposures. Contractor and installer qualification designations like Trowel of Excellence and ACT certifications speak to the skills of the installers. With the support of these standards, tests, and programs, the durability of tile is undisputed.?

Note: This article was adapted from another article by the same author published in the Fall 2021 issue of 093000 Contractor, a publication of Tile Contractors’ Association of America.

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