ANSI Guidelines for Ceramic Tile

Rely on ANSI Guidelines When Choosing Ceramic Tile.

When it comes to choosing tile, there are many things you should look for regarding performance and quality levels. Following ANSI Guidelines can result in quality tiling craftsmanship.The American National Standards Institute (ANSI) together with the American Society of Testing and Materials (ASTM) establish ANSI Guidelines for tile manufacturing in the United States. Those guidelines are shown on the label of every box of tile, in a standardized code. Understanding the code will help you buy the ceramic tile that’s right for you.

ANSI 137.1 (1988) presents standard specifications for ceramic tile. It lists and defines various types, sizes, physical properties, and grading procedures for ceramic tile, including mosaic tile, quarry tile, pressed floor tile, glazed wall tile, porcelain tile, trim units, and specialty tile.

Ratings. There are five ratings categories listed on every box of glazed ceramic tile and four ratings categories on every box of unglazed tile.  Be sure to read the label. Look for a given tile’s grade, PEI rating, water absorption, coefficient of friction, frost safety and tone. The ratings are as follows:

Grade. A tile will have a grade from one to three. Grade one is the highest quality, grade two is similar to grade one but it will almost always be less expensive. Grades one and two are suitable for floors. Grade three tile are only intended to be used on walls. Though you can use floor tile as wall tile, you cannot use wall tile as floor tile.

Wear rating or PEI rating. PEI stands for the Porcelain and Enamel Institute’s wear rating. PEI rates a glazed tile’s ability to resist abrasion and its suitability as a floor tile. Only glazed tiles get a a PEI rating. If you’re buying unglazed tile you won’t find this category on the the label.

Ceramic tiles rated PEI I and II are appropriate for use as wall tile only. They cannot withstand foot traffic. Tiles rated PEI III offer moderate resistance to wear and they are appropriate for most residential uses. Tiles that carry a PEI IV are highly resistant to wear and appropriate for all residential and some light commercial uses. Tile rated PEI V are the most resistant and are appropriate for use in heavy commercial locations. Anything rated higher than a PEI III or PEI IV tile is overkill for residential uses.

Water-absorption rate. .A tile’s W.A. rating will tell you if a tile is the right tile to use in a wet area or outdoors. There are four categories in the W.A. rating and they’re expressed as a name and percentage of water absorbed by a tile.

  • Non-vitreous tile absorbs more than 7% of its weight in water and is inappropriate for use outdoors or in a wet area such as a bath or spa. Semiviteous tile absorbs between 3% and 7% of its weight in water and it too is only appropriate for use in dry, indoor areas.
  • Vitreous tile absorbs only 0.5% to 3% of its weight in water and it’s a rating you want to see if you’re using a tile outdoors or in an area where there’s a lot of moisture present.
  • impervious absorbs less than 0.5% of its weight in water when exposed.

Porcelain tile is in the impervious category, Tile label as porcelain carry a price premium. Tile categorized as vitreous has to be called ceramic. Ceramic tile of the same grade and wear ratings to that of a porcelain tile are less costly and are an appropriate candidate in a residential setting.

Slip resistance. Slip resistance is a given tile’s coefficient of friction, abbreviated as C.O.F. The COF refers to a tile’s natural resistant to slip and it’s measured by the force required to slide an object across a surface divided by the object’s weight. Lower C.O.F. numbers indicate less friction and the floor will provide less traction. Higher C.O.F. numbers indicate that a floor will be less slippery.

A C.O.F. greater than .50 is recommended for standard residential applications. A C.O.F. greater than .60 is required for commercial applications and to meet Americans with Disabilities Act guidelines.Pay attention to that C.O.F rating in bathroom and kitchen areas. The higher the number, the less likely you’ll be to slip on a wet surface.

Frost. Frost is a simple either/or rating and it tells you whether can withstand freeze and thaw cycles outdoors. If you’re using a tile indoors, this rating doesn’t matter.

Tone. Tone only applies when there is intentional variation from tile to tile to mimic the look of natural stone. If you’re looking for a tile with consistent color, toned tile is not for you. The code is shown as a shaded grid indicating that the carton contains variations in tone from tile to tile.  That is not unusual . It is true for most types of tile, except for pure colors, such as black and white.

In some instances tone is shown instead as a “variation” code:

  1. V1 (uniform coloring).
  2. V2 (slight variation).
  3. V3 (moderate variation).
  4. V4 (random variation).

There is one factor not covered by the ANSI guidelines that should be considered–break strength and glaze hardness.  The featured image above of the piano sitting on a porcelain tile installation illustrates an instance where choosing a porcelain tile rather than a ceramic tile might be justified.  Typically, a certified porcelain can usually take around 500 lbs per square inch of pressure before breaking, whereas a ceramic tile’s breaking point is around 150lbs per square inch.   Those figures only apply when the tile has been properly installed.  The breaking point drops dramatically if the tile under pressure has empty space under it.

As that piano like weights around 600 pound, were there no coaster under each of its legs, tile breakage could be an issue.  And, if breaking didn’t occur, the tile’s glazed surface would likely be damaged.

Finally, something to think about.  Ask yourself, how did that piano ended up where it is without doing some kind of damage.


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My tiling service areas include Port St. Lucie (PSL), Fort Pierce, Stuart and Vero Beach, FL.