Types of Ceramic Tile

- John P. Bridge.

Ceramic Tile Information for do-it-yourselfers, pros and consumers is available at the John Bridge Tile Forums.

The term “ceramic tile” is a rather loose one, inasmuch as a number of tiling and paving products are included in the description. Ceramic wall tiles made from  the same material figurines are made from; monocottura (single-fired) floor tiles; rock-hard porcelain tiles; and mosaic tiles made from clay are some of the varieties called “ceramic tiles.”

• Wall Tiles

A wall tile is any tile used primarily in applications other than floors. The most prevalent of these are “standard American wall tiles,” which also go by the term “four-and-a-quarter,” since they are approximately 4 1/4 inches square.

Four-and-a-quarter tiles are those which have been used in bathrooms since the advent of inside plumbing in this country. Many companies make them, and thus there are myriad colors and textures available. Trim pieces or “shapes” are available for every style of standard wall tile made. This is important when it comes to building showers and other structures that require outside corners and edges.

Four-and-a-quarter tiles are almost always formed from the white ceramic clay used in figurines. The tiles are water-resistant but not water-proof.

There are a number of porcelain tiles which are also designed to be used on walls and surfaces other than floors. Most of these are glazed, and many of them are made in other countries, particularly Asian countries including Japan and Korea. Many times these tiles arrive mounted on backing sheets which facilitate their installation. Porcelain tiles, glazed or unglazed, are virtually water-proof.

Tiles used at the waterlines of swimming pools are usually glazed porcelain tiles. These are almost always imported from other countries, most notably Japan.

[Note:] For the past several years I’ve been using larger floor tiles in showers. It’s been a while since anyone has asked for the wall tiles mentioned above. Bigger seems to be better. Additionally, most of the floor tiles you’ll find nowadays are made from porcelain clay, which is a good thing when durability is important. “Porcelain” tiles, by the way, are those with a water absorbtion rate of less than .5 percent.

• Floor Tiles (glazed)

Almost all the glazed floor tiles used today are single-fired “monocottura” tiles. They are made by the process known as “dust pressing,” wherein very little water is used, and the bisques or tile bodies are compacted under extremely high pressure.

Glazing is then accomplished, and the tile is cooked at high temperatures, usually over 2000 degrees f. A tile produced in this manner is very durable and will last indefinitely.

• Grading

In the United States there are five grades assigned to floor tiles, whether they are imported or produced in this country. The grades are in Roman numerals, with grade I being the lowest and V the highest. I know of no one who makes grade I tiles however, so let’s start with II.

Grade II tiles can be used in residential applications where light traffic is expected. Bathroom floors, for example, do not receive very heavy traffic.

Grade III tiles are adequate for any residential use, including kitchen and entry floors, which receive considerable traffic. These tiles might also be used in light-traffic commercial applications — perhaps beauty parlors and other businesses where there is not a heavy and continuous volume of foot traffic..

Grade IV tiles are rated commercial, although they are also commonly used in homes. These tiles will hold up in just about any application, including grocery stores, bank lobbies, etc.

Grade V tiles are used in industrial settings, where they are expected to receive heavy abuse and exposure to various chemicals. Not many grade V tiles would be used in the home. They usually look too commercial.

Tile grades are never stamped on packaging, so you are at the mercy of the person selling you the tile. This is one of the reasons I suggest you do your shopping at established tile supply locations and not at discount stores and home centers. Only people who specialize in a product are going to know a great deal about it. Home center employees, for example, simply have too many products to keep up with.

• Quarry Tiles

Quarry tiles are made from the same clay bricks are made of. Quarry tiles, including brick pavers, paving bricks and paving tiles are all from the family known as “burnt clay.” These tiles come in different sizes and shapes: some are square, some are irregular, and some are generally shaped like bricks laid flat — about four by eight inches or so.

All of the burnt clay materials are extremely durable, inasmuch as they are fired hard, and the color pigments go all the way through from top to bottom. They are rated at grade IV or V. Quarry tiles will never wear out no matter how much abuse they’re subjected to.

• Porcelain Floor Tiles

Porcelain tiles are probably the hardest products we install. They are dense to the point that they are water-proof, and they are extremely difficult to cut. We wear out more cutting tools on porcelain tiles than on any other product.

Unglazed porcelains are often used in commercial and industrial applications. During manufacturing they can be given non-slip surfaces which make them desirable in outdoor settings and in other instances where the tiles can be expected to become wet. I installed unglazed porcelain tiles in bank lobbies for years — all over Texas, as well as in Louisiana, Arkansas, and Mississippi.

Recently we have encountered more and more glazed porcelain tiles, which are wonderful for residential use. The glaze gives them a warmer look than the unglazed versions. These tiles are generally more expensive than their clay counterparts, though.

[Note] 4/7/2011 Almost all floor tiles used in the U.S. and Canada nowadays are made from porcelain. I don’t expect the trend to change. Porcelain tiles have a water absorption rate of .5 or less. There are tiles labeled porcelain that do not meet the absorption standard. If you have any doubt, ask to see the product data. If none are available, move on.

• Mosaic Tiles

Mosaics are any tiles, glazed or unglazed, that measure 2 inches square or less, although they don’t necessarily have to be square. Some of them, in fact, are hexagonal in shape and others are rectangles. It doesn’t matter what the tiles are made of, however most mosaics are made from porcelain, and most of them are left unglazed.

Mosaic tiles are used extensively in commercial applications. Walk into a commercial restroom, and you’ll probably notice porcelain mosaic tiles on the floor and possibly on the walls as well.

We often use mosaics to form residential shower floors. The small size makes it feasible to “dish” the shower floor so that water readily flows toward the drain. It is almost impossible to accomplish this with larger pieces and make the job look good. The numerous grout joints between the small tiles provide a great deal of “tooth,” and this translates to slip resistance on bare feet.

Mosaic tiles are always mounted on sheets of backing paper or netting — or they are joined together with small spots of synthetic rubber. It has been at least fifty years since they were delivered and installed individually. Can you imagine the time that took?

There are also natural clay tiles, including terracotta tiles and Saltillo tiles. Terracotta tiles are the color of the clay from which they are produced, ranging from grays to browns and reddish orange. They are left unglazed and require a top finish after installation. Saltillo tiles are covered in another article.

An important consideration for all tiles installed outdoors is whether the tiles are “frost-proof.” This is especially true in northern climes where freezing conditions are commonplace. Generally, the degree of frost resistance in a tile is determined by its propensity to absorb water. In this sense, tiles that are water-proof are also frost-proof.

Since water expands when it freezes, if it is allowed to get in or under tiles in freezing conditions, it can cause the tiles to crack and come loose. Many ceramic floor tiles, porcelain tiles and all quarry tiles are safe bets for outdoor applications. Terracottas and other natural clay tiles, including Saltillo tiles should not be used in areas where hard freezes occur.

I know I haven’t covered everything, but that cannot be done in a brief article. If you want to know more about the characteristics of various tiles, you can visit the web sites of some of the manufacturers. Most of them have a wealth of technical information stored on their sites. Some manufacturers are listed on our links page. Others can be found using Internet Search Engines. Try searching for “tile manufacturers”.

A wealth of free information is  available at the John Bridge Ceramic Tile Forums.

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