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How To Select The Right Tile

What the heck do all those numbers, grades, and terms really mean?


To understand the quality and durability of ceramic and porcelain tiles we are able to turn to both the (ANSI) “American National Standards Institute”, as well as the (ASTM) “American Society For Testing Materials”, which provide the testing procedures and standard values for tiles.

Water Absorption Test ASTM C373
Can this tile be used in a shower, what about a swimming pool?

One method for classifying ceramic tile is by the percent of water absorption as measured by this test. Individual tiles are weighed, saturated in water then weighed again. The percent of difference between the two conditions is refereed to as the water absorption value. Four categories of tiles are established using these results as a guideline.

Impervious: Tile with water absorption of 0.5 percent or less.
Vitreous: Tile with water absorption of 0.5 percent to 3 percent.
Semi Vitreous: Tile with water absorption of 3 percent to 7 percent.
Non Vitreous: Tile with water absorption in excess of 7 percent.

The smaller percentage of water absorption the better the tile will perform when placed in a submerged or wet application. Non Vitreous tiles are not even recommended for floor use.
This test is also sometimes used as a good indicator to predict the stain resistance of unglazed tile, the lower the absorption the greater stain resistance.

Chemical Resistance Test ASTM C650
Will this tile be alright in a beauty salon, what about a commercial setting where harsh chemicals are used?

Resistance to chemicals may be an important consideration in the selection of tile for a specific application. The standard testing procedure involves placing the tile sample in continuous contact with a variety of chemicals for 24 hours, raising the surface and then examining the surface for damage or variation.

MOH’S Scale Rating “Do Not Confuse With PEI Rating”

The relative hardness of glazed tile is an important issue that should be addressed when selecting a tile. Scratching the surface of the tile with different minerals at the same pressure performs the test and subjectively assigns a “MOH’S Scale Hardness” number to the glaze. The softest mineral used is talc, #1 if no scratch; the hardest is a diamond a #10 if no scratch. Other minerals of varying hardness make up #2 through #9. A value of #5 or greater is suitable for most residential floor applications. A value of #7 or greater is normally recommended for commercial or high traffic applications.

Abrasion Resistance Test “PEI Rating” ISO 10545-7
PEI – Porcelain enamel institute

The durability of a tile’s glaze can be measured, subjectively, by observing the visible surface of the tile when subjected to this test. Usually an abrasive paid is ground against the tile for a period of time. The amount of damage done to the glaze is recorded and assigned a PEI rating of #1 – #5.

Class 1: Generally not recommended for use on floors.

Class 2: Residential floor coverings in areas subject to soft-soled to normal footwear traffic with no scratching dirt. Domestic bathrooms and bedrooms without exterior access. (Light Traffic)

Class 3: Residential floor coverings in areas subject to normal footwear traffic with small amounts of scratching dirt. Rooms in living areas of homes except kitchens, entrances, and other areas that may be subject to high traffic. (Medium Traffic)

Class 4: Residential or light commercial floor coverings in areas subject to normal footwear. Halls, kitchens, entryways. (Medium-High Traffic)

Class 5: Commercial or residential floor coverings in areas subject to high traffic and scratching dirt. Malls, hotels, airports. (Heavy Traffic)

All floors should be adequately protected against scratching dirt in entrances to buildings by
either floor mats, or some other footwear-cleaning device.

I have heard many salespeople till their clients that all porcelain tiles are Class 5. This is NOT true, most porcelain tiles today are glazed just like their ceramic cousins and may be just as easily scratched or worn. Sometimes the only difference is in the body of the tile, not the glaze.

Coefficient Of Friction Test ASTM C 1028
Will this tile be too slippery for my bathroom floor?

This test establishes how much effort it takes to move an object across the face of the tile dry or wet. This is essentially important when choosing floor tile in an attempt to minimize slip and fall injuries. For example, the American with Disabilities Act (ADA) requires that floor surfaces be stable, firm, and slip resistant. Further, the Building Code for the City of Los Angeles, California (USA) requires that level surfaces have a COF of not less than 0.6 and ramps no less than 0.8 when tested.

Breaking Strength Test ASTM C648

Ceramic tiles used on floors and walls must be able to withstand the expected load bearing capacity of various installations. In order to determine the breaking and flexing strength of the tile there is a standard test method used to evaluate individual pieces. A force is applied to an unsupported portion of the tile until breakage occurs. The ultimate breaking strength is then recorded in pounds. Final selection of the tile should be based upon the breaking strength and appropriate installation method.

Freeze/Thaw Resistance ASTM C 1026

Establishes the tiles ability to resist freeze thaw damage. Tiles that are not frost resistant could have problems with the glaze flaking off, and or cracking.

What’s the deal with porcelain tiles?

Doesn’t it seem that everything is switching from ceramic to porcelain? Due to the internet and shows on HGTV, consumers are now more aware than ever that they need porcelain tile for their home. Most of them just don’t know why.
If made correctly by a good factory porcelain tile Is superior to ceramic. Let me say that there is nothing wrong with ceramic. Ceramic tile has been used for thousands of years and holds up great. I feel that the reason we have seen so much porcelain lately is due to other countries having the ability to undercut the Italian market. The Italians have no other choice than to switch most of their production to porcelain to compete with the quality to price ratio. There was the same change about 10/15 years ago when everything went from red bodied ceramic to white bodied ceramic.
Unglazed Porcelain
Unglazed porcelain tiles are very tough and extremely dense. Porcelain Tiles are manufactured by dust pressing in dyes at very high pressure and are then fired in a kiln at over 1200 degrees C.
They are a through color product “the color goes through the whole body of the tile” and in very heavy traffic ie:- industrial flooring situations, they may wear, but will retain their original color.
They are available with various finishes from matt to a very high polished gloss, to rough textured. They are also available with a rectified edge this means tile edges are ground to an exact tile size with a square edge finish.
Glazed Porcelain
Again extremely durable products which are glazed on top of the dense tile body. This glazed product unlike the unglazed porcelain can have pattern, varying colors and stone look-alike finishes.
Glazed porcelain tiles can have just about any type of finish. They can be ground and polished to produce a completely flat surface. They are also available in the rectified finish, as described under the unglazed porcelain. Glazed porcelain can also be a semi through bodied tile, the color of the body can be matched to the glaze color. Therefore chips would not be as noticeable.

We hope that this information will help you to correctly answer your clients questions and assist them in selecting a tile that is just right.