||Group I||The softest tile. Suitable for walls and hobby crafts only, no floors.
||Group II||Residential use in low foot traffic areas. In rooms where there is usually no through traffic, this tile might work. But, in kitchens, where there is often a lot of through traffic, this tile would be suspect.
||Group III||All residential, medium commercial, normal foot traffic (interior only). Any bathroom or kitchen, mudroom, laundry room or hallway, but nothing outside.
||Group IV|| Heavy commercial. Any interior use. Suited for residential floors that get a lot of use and for exterior applications where there is not a hard freeze in winter.
||Group IV+ (or V)||The hardest tile. Extra heavy, high traffic, commercial (interior or exterior use).
|Rating ||Description ||Application
||Water absorption of more than 7.0% by volume.
||Tile for non-wet areas. Around fireplaces, for example. Typically intended for walls, hobby and crafts use.
||Water absorption of more than 3.0 percent, but not more than 7.0 percent.
||Tile for areas that may get wet on occasion, but are unlikely to see constant or standing water. Kitchen backsplashes or countertops, for example.
||Water absorption of more than 0.5 percent, but not more than 3.0 percent.
||Virtually any indoor application including shower walls and floors. Outdoors in areas that do not freeze.
||Water absorption of 0.5 percent or less.
||Any indoor or outdoor application.
"…generally made by the dust-pressed method of a composition resulting in a tile that is dense, impervious, fine-grained, and smooth with sharply formed face."While this is definitely written in engineer-speak, what it does is define two different tests for identifying a porcelain tile. The first is the same performance test used to rate all tile. A porcelain tile must perform at the highest, "impervious", standard in the ANSI water-absorption test (See above). The second is something new — a "process" test. To be called porcelain, tile must be made by the dust press method or process.
|This grade is the result of a visual inspection. The range is 1 to 3, the lower the number the better the tile. A grade 1 or Standard Grade tile exhibits no obvious imperfections when visually inspected at a distance of 3 feet. A grade 2 tile shows no visible imperfections at a distance of 10 feet. Almost all tile in a tile store will be grade 1. Sometimes you will find grade 2 tile on a "special purchase" sale — often at quite the discount. Grade 2 is just fine for many applications. The durability of a grade 2 tile is usually not suspect, it merely has visible imperfections. We sometimes use it in historical renovations to simulate 19th century tile that often had many visible flaws. Grade 3 tile is rarely seen in retail stores. It usually has major aesthetic problems including wide variations in tone and sizing. Let the tile professionals buy this tile. They know where and how to use it.|
|This is the result of the PEI wear test that we introduced earlier (See chart above). Many manufacturers use this test only on floor tiles. The higher the rating, the more wear-resistant the tile. A tile used as flooring or on a countertop should be rated at least in Group III. A higher rating is even better for floors. It should also be at least 1/4" thick. Thicker is generally better. If the tile is glazed, then it is the glaze coating that is tested. If the tile is un-glazed, such as in quarry tile, the tile body itself is tested. If this rating is missing, the tile is probably not intended for floors — and will usually say so right on the box.|
|This is the score the tile received on the ANSI test for resistance to water penetration (See chart above). A tile that is installed outdoors where there is a real Winter should be rated impervious to water penetration. Otherwise, water trapped within the tile may freeze, fracturing and cracking the tile. For indoor applications, semi-vitreous and vitreous are strong enough for floors, and non-vitreous for walls. In some locations where the freeze is neither hard nor long, vitreous tiles can be used outdoors — not recommended in Nebraska, however.
A tile rated "impervious" to water absorption may be called "porcelain" under the ANSI standard for porcelain and may be certified by the Porcelain Tile Certification Agency, a trade group, as "porcelain" under the ANSI definition. It does not have to be certified, however. It is the manufacturer's option.
All tiles called "porcelain" do not necessarily rate "impervious" in this test. Don't rely on the word "porcelain" on the box, look for this specific test rating or the PTCA certification of "porcelain".
|For floor tile, this Coefficient of Friction (COF) ranking is important. The test establishes how much force is required to move an object across the face of the tile, dry or wet. It tells you how resistant a tile is to slipping. The higher the score, the more slip-resistant the tile. Tile COF can be rated "wet" or "dry". For a general floor, look for a dry rating of 0.5 and above. For a bath or kitchen, where the floor is likely to get wet, a wet rating of 0.5 or greater is required and 0.7 or higher is better. Some tiles specifically designed for wet floors are rated above 0.85.
COF is an important consideration, especially in wet areas. One of my neighbors ignored COF when selecting impervious tile for his front stoop, and now, on wet days, you have to tip-toe over the tile with a death-grip on the handrail to avoid major injury.
There are problems with this test, however. The testing process involves pulling a weighted board with a Neolite (rubber) sole (used to simulate the bottom of a shoe) along the surface of a test tile. This is called a static slip test. However, the way we walk involves more than just slip-sliding along. There is both downward and outward force applied with each step we take. The standard slip test tells us nothing about the effects of these forces.
To test downward and outward force, what's needed is a dynamic test. There are a number of dynamic resistance tests, but none has yet been approved for testing tile in the U.S. The most widely accepted test in Europe is the ramp test (DIN 51130). The test involves a person walking along a platform of tiles that are being tested. The incline is then increased to a point where the person starts to slip. Obviously, since people react differently when anticipating a slip — including changing their stride and walking more carefully — and some acrobatic individuals can airily skip down slippery slopes that would kill us clumsier types, this test has some basic reliability problems. It has not been adopted outside of Europe.
|If present, the "Frost" icon merely tells you that the tile is able to withstand repeated cycles of freezing and thawing. If there is no frost icon, it may mean that the tile is not suitable for use outdoors in any place where it might freeze, or the tile maker did not bother to order the test. A more reliable guide is the tile's rating on the water absorption (W.A.) test, above, for which almost all tiles are tested.|
|The tone and shade rating is an indication of how much variation there is in the color and shade of the tile. The range of ratings on this "V" scale is V1 to V4.
|9||Corundum||4||Fluorite||Pocket Knife Blade/Steel Screw|
|7||Quartz||Case-Hardened Steel File||2||Gypsum||Fingernail|
|Don't||pay any attention to the word "porcelain" on a box of tile. It does not tell you anything particularly useful.|
|Do||read the ratings on the box. Even if there are no handy icons, the ratings are probably in the fine print somewhere. If there are none, pass it by. You do not want to buy untested tile because you have no idea what you are getting. If you have questions about a rating or whether a tile will work for the application you have in mind, ask them of the manufacturer, not the clerk. The clerk probably knows less about it than you do after reading this article.|
|Don't||buy a better tile than you need. If you buy an impervious tile for your shower walls, you have probably paid more for features you don't need such as very high wear and frost resistance. A semi-vitreous tile would work just as well, and most likely cost less. Of course, if you just found the tile sale of a lifetime, forget all this.|