One is hard, the other soft. Both are renewable natural materials. They look like wood, but one is a kind of grass and the other is tree bark. Their qualities make them suitable for use in floors, and they are easier than ever to find, buy, and install. These materials are different
enough from traditional hardwood flooring, however, you should know more about them before deciding to use either one.
About Cork
Cork is the bark of the evergreen oak tree Quercus suber, which is native to southwest Europe and northwest Africa, which means almost all cork used in the United States must be imported. Most imported cork comes from the Iberian Peninsula, which includes Spain, Portugal, Andorra, and Gibraltar. Cork is also produced in Algeria, Morocco, Tunisia, Italy, and France.
While it can be grown in warmer parts of this country, it has only been successfully planted in California, where its need for direct sunlight and resistance to drought are not problems. Cork oak trees grow to be 40 to 65 feet tall, with thick layers of bark. Like other oak trees,
it produces acorns as seeds. And unlike many trees that die when their bark is removed, the cork oak just grows more.
The bark can first be harvested when the tree is about 25 years old, and after that every 10 years or so. Cork oak trees live for 150 to
250 years. Because each tree has a different shape, cork harvesting is traditionally done by hand.
Once harvested, cork is durable yet light and nonflammable. The cells of the bark are filled with air; they can withstand high pressures without rupturing, and will return to their previous shape. Cork has been used for insulation, packing material, and veneer, among other things. The cork we use in bulletin boards and wine bottle stoppers is the same cork used in flooring.
Cork Floor Coverings
Although only 15 percent of the cork harvested is used for wine bottle stoppers, that industry accounts for more than half of the money earned by cork producers. Understandably, wine makers get first pick of the available cork supply. Using stock that was not chosen by wine makers, as well as leftovers, flooring manufacturers grind cork into a uniform mixture. Then they add just enough adhesive to hold the material in shape, and press it into sheets. The squares and panels you see did not come straight from the tree.
Natural cork varies in color, and manufacturers sort it to produce a variety of tones. They may also add dyes to give the cork flooring a more consistent or dramatic look. Common colors range from alabaster to espresso, with most variations on a continuum between
khaki and chocolate. Visual texture varies, too. Some cork products have no more directional grain than sand on a beach; others have the appearance of burl oak.
As a result of its composition, cork flooring is not strong by itself. Only when it is installed on top of a stable subfloor does it take on the strength that complements its other qualities. Remember that cork flooring is loose material formed under pressure; the larger a square
or sheet of cork is, the more expensive it is to create, the more fragile it is, and the harder it is to install. That’s why most cork flooring is sold in single tiles rather than rolls.
Once installed, a cork floor is comfortable underfoot, hard enough to withstand heavy foot traffic, soft enough to cushion falling objects, pleasant to look at, and resistant to fire, mold, and mildew. Its natural cushioning also adds insulation and helps control noise. With regular care, cork flooring will last for decades.
About Bamboo
Strictly speaking, bamboo is a grass—not a tree. More than 1000 species of bamboo are grown around the world. Some thrive in mountains with cold winters, while others only appear in tropical climates. For the most part, bamboo does not grow in Europe or Canada, and is seldom cultivated in other northern countries.
Where it does live naturally, bamboo grows very quickly. Some of the largest species grow fastest of all, with new shoots gaining 3 feet per day. Bamboo is one of the only plants whose rapid growth can be heard and seen as it happens.
The genus Phyllostachys includes several large species of bamboo that are large enough to use in building products. These are known as timber bamboo. In addition to growing vertically, these types of bamboo spread quickly through rhizomes under the surface of the soil. In fact, they are even considered invasive species in places like California, where they are not native. Of the roughly 75 species and 200 varieties of Phyllostachys, the largest can grow to be about 100 feet tall.
To minimize impact on wild habitats and maintain consistency in the harvested product, some companies that make bamboo products have established their own plantations. Whether cultivated or collected, mature bamboo can be harvested every five years or so.
Bamboo Floor Coverings
By itself, bamboo is not a suitable replacement for wood in flooring. Individual stalks of bamboo can be used in building, but flooring has to be broad and stable. To become a useful flooring material, bamboo must be shredded and then formed into regular shapes, such as planks and tongue-and-groove boards, under high pressure. As with cork, this loose material is held together with an adhesive or resin.
The adhesives and resins used to create bamboo flooring, transform an abundant natural resource into a durable building product. In keeping with the goal of environmental responsibility, manufacturers emphasize the use of adhesives that do not contain formaldehyde, and resins such as acrylic urethane that contain few or no volatile organic compounds. This helps the products meet standards for both green manufacturing practices and indoor air quality.
Once shredded bamboo is set in its new shape, it provides a flooring surface that is harder than red oak or maple, and thick enough to refinish several times. In tongue-and-groove boards, bamboo is available with vertical or horizontal grain, naturally colored or stained,
finished or unfinished. Bamboo flooring is also made as a laminate, with a 1/8-inch wear layer of bamboo adhered to a backing made of pine or other softwood.
Buying Tips
The increasing popularity of cork and bamboo has brought many manufacturers to the field, and their competing claims can be confusing. When you shop for renewable flooring materials, check more than just the price per square foot. Think about whether the material will still be appropriate if you change the way you use that room. Finally, ask installers which products they believe stand up best over time. Your investment in renewable materials will benefit the environment; make sure it also improves your quality of life.
