Most types of tiles that are made from a form of clay or a clay mixture, which are then kiln-fired, are considered to be a part of the larger classification of tile called ceramic. These tiles can be split into two groups, porcelain tiles and non-porcelain tiles. These non-porcelain tiles are commonly referred to as ceramic tiles.
Non-porcelain ceramic tiles are generally made from a red or white clay that is fired in a kiln. They’re easier to cut than porcelain and usually carry a PEI rating of 0 to 3 (see PEI Ratings below). Ceramic tiles are suitable for light to moderate traffic and have a higher water absorption rating that makes them less frost resistant than porcelain. In addition, they’re usually more prone to wear. However, with new technologies, ceramic tile should always be considered by its specifications, as durability and other factors will vary between ceramic tiles. Ceramic tiles generally cost less than porcelain tiles.
Porcelain tile is generally made by pressing porcelain clays, which results in a tile that’s dense, impervious, fine grained, and smooth with a sharply formed face. Porcelain tiles usually have a much lower water absorption rate than ceramic tiles, making them more frost resistant, although not frost proof. Glazed porcelain tiles are much harder and have more wear- and damage-resistance than ceramic tiles, making them suitable for any residential and light commercial application.
In order to enhance the stain resistance of a stone tile, many tiles are glazed. This means they’re coated with a liquid glass that’s baked onto the surface of the clay. In addition to protecting the tile from staining, the glaze also allows an unlimited array of colors and designs to be added to the tile. Porcelain tiles whose color runs all the way through the tile, rather than simply being baked onto the surface, are called full-body tiles. Since their color extends throughout the tile, these tile don’t show wear, making them ideal for commercial applications.
Ceramic Tile Wear Ratings
The current rating system for ceramic tile is the only reliable gauge for consumers to use in determining wear expectations for a particular tile application. The Porcelain Enamel Institute (PEI) has developed a rating scale that can effectively guide any consumer through the process of choosing the right tile for their particular application. This rating system is recommended by the American Society for Testing and Materials (ASTM).
- PEI Class 1 Rating (No foot traffic) – Recommended for wall use only in residential and commercial applications.
- PEI Class 2 Rating (Light traffic) – Recommended for both wall use and bathroom floor applications.
- PEI Class 3 Rating (Light to moderate traffic) – Recommended for countertops, walls, and floors where normal foot traffic is expected.
- PEI Class 4 Rating (Moderate to heavy traffic) – Recommended for all residential applications as well as medium commercial and light institutional.
- PEI Class 5 Rating (Heavy to extra heavy traffic) – Recommended for all residential as well as heavy commercial and institutional applications.
Most porcelain tiles have a PEI rating of 5, which makes them the hardest wearing tiles on the market.
Natural Stone Tiles
In addition to the many choices you have in ceramic tiles, there’s also a wealth of options among natural stone tiles. There are many subtle and significant differences between the types of stones available, from appearance to water absorption to durability. The natural stones most commonly used in tiles are slate, marble, limestone, travertine and granite.
Slate is a fine-grained, metamorphic rock, commonly derived from sedimentary rock shale. It’s composed mostly of micas, chlorite, and quartz and is best suited for floors, walkways and roofing, and recently has been used attractively for kitchen countertops and wet bars.
It’s a dense, very tough composite that’s typically available in blacks, grays and greens, although many other colors can also be found in slate products. Slate shades within the same color family often vary. Veined patterns from overseas have also recently been introduced. Unless it has been honed smooth, slate’s surface can be recognized by its distinct cleft pattern.
Marble is one of the more popular natural stones, formed from fossil sediment deposits that have been pressed by the natural geologic forces of nature for millions of years. Much as diamonds are created from coal, marble was once limestone that underwent a metamorphosis from the intense pressures and high temperatures within the earth.
The combination of the natural materials in these deposits, along with natural geologic events, produces unique colors and veining with a richness of depth and intensity. Most marble products are generally softer than granites and have more porosity than granite. Since marble is a softer stone than granite, it’s most often used in bathroom walls and flooring, as well as for tub decks, fireplace surrounds, furniture, sculptures and courtyards. Marble is not recommended for kitchens unless the stone is honed and sealed.
Limestone is a form of marble that’s less dense than marble or travertine (see below). Limestone is a sedimentary rock consisting mostly of calcium carbonate and is formed from the remains of ancient sea life, such as oysters, mussels, and other ancient shellfish and invertebrates, that have dropped to the sandy bottom of ancient seas and then compressed over millions of years.
Limestone is a common stone found in many parts of the world in excellent abundance. Limestone generally varies in earthy colors such as off-white, grey or beige. If the limestone contains the mineral dolomite, it becomes harder in nature and can be polished to a shine much like marble can. Its best uses are for structural walls, entry walls, floors, fireplace surrounds, vanities and shower walls. It’s generally not recommended for kitchen countertops and wet bars because fruit juices and alcohol products can stain it and limestone is prone to scratches.
Travertine is a variety of limestone formed in pools by the precipitation of hot mineral-rich spring water. Travertine is another form of marble that’s less dense than a high-grade marble and highly porous. The divots that are characteristic of travertine were created by carbon dioxide bubbles that became trapped as the stone was being formed.
Travertine can have a honed, unfinished surface, or the holes can be filled and then polished to a high gloss. It’s best used in entry walls, floors, fireplace surrounds, vanities, shower walls, tub decks and mosaics, but is not recommended for kitchen or wet bar countertops since it can be easily scratched. It can also be easily stained by fruit juices and alcoholic products. Its colors usually range from light beige to brown. Travertine does require a degree of special care, as some cleaning products can be destructive to its surface.
Granite is a dense-grained hard stone. It’s actually the second hardest known substance next to diamonds. Granite is an igneous rock formed either from the melting of sediments deep within the earth or through magma (lava) activity that has heated and cooled. These sediments were held under extreme pressure and temperatures for millions of years, then brought to the surface of the earth through upheaval of the crust that formed mountains. This process produces granite, a quartz-based product, which combines strength and durability with rich patterns and veining.
Minerals within granite typically appear as small flecks throughout the stone, often creating a salt and pepper look. Other types of granite have veining similar to marble. Once polished, natural granite will maintain its high gloss finish virtually forever. It also cleans in seconds. Because of its durability, it can be used successfully on kitchen countertops, wet bars, entry walls, floors, fireplaces and bathroom vanities. Flamed or honed granite can be used almost anywhere.
Buyers should note that no two natural stone tiles will be the same-each has its own natural beauty. Homeowners must be sure to seal the stone periodically, however, in order to maintain that beauty.