Hicksville, N.Y.—The next time someone tells you to “just put a cork in it,” don’t take offense. It’s good flooring advice. Cork is a floor covering material whose time has come, again. Floors made of cork were popular around the globe and especially in the United States for generations. In fact, the original floor covering offered by Armstrong World Industries was cork-based, back when the company’s name, Armstrong Cork Company, reflected its product line. The middle of the 20th century saw the decline of cork flooring and the advent of more contemporary floor coverings, including no-wax vinyl and colorful carpets.

But, the many benefits of cork flooring are at the root of a renewed interest in the product for residential and commercial interiors. Natural, Renewable Cork is a favorite of environmentalists who want “green” materials in buildings and for consumers who want natural materials in their homes. Believe it or not, it may be the most environmentally correct flooring product available, as the tree is not harmed in the cork-collecting process. Cork comes from an oak tree, whose botanic species is Quercus Suber. To obtain the cork, the outer bark is peeled from the trees when they reach maturity, at 20 years of age. The inner bark is left intact to protect the trees and form the base layer for the next growth cycle. When the outer bark regenerates, in approximately nine years, it is harvested again. Cork oak trees are the only known trees that can regenerate their outer core after each harvest, with no harm to the tree. The trees live for approximately 150 years before their useful cork-bark-producing lifespan comes to an end.

Joaquim Mota of Amorim Floors, parent company of both the Wicanders commercial and Ipocork residential brands, says, “These trees grow primarily in the Mediterranean, with approximately 50% and 25% coming from Portugal and Spain, respectively.” Cork is also produced in Algeria, France, Morocco, Italy and Tunisia. The quality of the cork varies from forest to forest and tree to tree, as well as from the same tree depending on the exposure to sunlight. The first bark harvested is called virgin bark. It has an irregular exterior surface and grayish color. It is suitable for grinding into various granule sizes for use in floor coverings. The bark, which grows out after the virgin bark has been striped is called refugo. It has a much smoother surface and brown color. The first refugo crop is also mostly used for grinding. The successive stripings have a finer appearance and are used in products ranging from cork stoppers to decorative items.

Another environmentally appealing aspect of cork is not just the no-harm harvesting process. While some manufacturers purchase cork directly, others buy cork that is recycled from other manufacturing processes, such as scrap from bottle stoppers. Almost all cork flooring can reuse its own in-house scrap during the manufacturing process, which further limits the amount of waste that would otherwise be sent to landfills. Cork flooring itself is made basically one of two ways: Tile is made with cork pieces or granules combined with resin binders, which are then formed into blocks, baked and cut into tiles or planks. Cork tiles are therefore composites but, essentially, are solid cork. Cork floating floors, which are similar to laminate floors in construction, are often made with a decorative cork veneer over engineered wood layers or particleboard. “There are also wood veneer floors paired with cork that offer the end user the beauty of wood and the unique technical properties of cork,” adds Mota.

Walking On Air Cork practically defines resilient flooring. This is not a misprint—every cubic inch of cork flooring contains 200 million closed air cells. Each infinitesimally tiny cell has 14 sides. The result is incredible comfort and resiliency underfoot for standing or walking. As Mota notes, “It’s like walking on air.” This underfoot comfort is beneficial for residential rooms including kitchens and playrooms, where people stand for long periods of time. Ann Wicander (no relation to the Wicanders brand that Amorim uses), president of WeCork, also confirms resiliency as one of the product’s main selling points. “Cork’s natural, comfortable shock absorbency makes it great for people with back, knee or joint problems. Items dropped on cork are less likely to break than on harder surfaces, even other resilient floor coverings.” Those qualities also put cork at the top of the consideration list for indoor athletic surfaces.

Heavy pressure does not break down or destroy the air cells, so the resilient material has a lot of memory. Cork is especially suited for gymnasiums, as it also has natural anti-skid characteristics. For all these reasons, says Philippe Erramuzpe, president of Natural Cork, “Cork floors are more comfortable than carpet or vinyl for everything from walking and standing to sitting.” The millions of air cells give cork effective sound deadening qualities as well. For years, it has been used to muffle noise on floor, wall and ceiling surfaces. Cork can help control sound created directly on the floor, such as walking, and ambient sound that emanates from the rest of the room, such as speech or music. Sound absorbency makes cork desirable for “quiet” rooms including libraries, museums, conference rooms, residential dens and baby nurseries.

It also has natural warmth, and not just in looks. Unlike cooler hard surface products, cork is warm to the touch. “This makes it an excellent insulator,” said Erramuzpe. He noted the thermal properties make cork perfect for areas where people spend a lot of time barefoot on the floor, or playing on the floors, such as bedrooms, nurseries and dens. As for bathrooms, cork’s resiliency, shock absorbency and warmth make for a great floor. However, here, proper installation and maintenance are extremely critical, as standing water and cork make for a bad combination. Healthy Choice Cork floor manufacturers also tout the material’s inherent antimicrobial characteristics and hypoallergenic properties. Manufacturers’ literature and Web sites proudly state the floor will not harbor bacteria or dirt. As an essentially flat floor, the surface is easy to clean and keep sanitized.

Cork isn’t known as an allergen or known to cause skin sensitivity for most people. In fact, Ken Riley, director of sales for BHK of America, said because the product is hypoallergenic, “tiles and floating floors with cork tops are healthy choices for residential and commercial interiors.” According to Erramuzpe, the product also has excellent fire resistant properties. “Cork burns slower than wood. It’s more likely to char than to burn, and scorch marks can be buffed out of the product if a burn does occur.” The product is also naturally antistatic, which is a terrific value-add in winter or in low humidity areas where static shocks seem the norm. “There are so many natural advantages to cork,” says Charles Helton, director of Arcobel USA Corp. “It’s easy to see why cork flooring is being rediscovered.”

Although cork is a resilient material it is essentially a wood floor. “It is wood!” Helton proclaimed. “It has the same federal specifications, maintains the same as hardwood, and has a similar look.” Cork flooring also has a similar price range as wood for total installed costs. “About $7 to $10 per foot installed as a median price.” In Style, New Styles Your grandmother’s cork floor probably had a natural brown hue. Back then, color variations in natural cork floors were dependent upon the bark’s indigenous hue, which could be deepened by baking the floor for longer periods of time. Today, consumers and specifies want more options, and cork is able to give it to them. The choices span a wide range of natural and enhanced colors created with stains and urethane finishes. The floors even come in white.

The time-honored way of coloring cork floors is still practiced by many manufacturers. Like a cookie, the longer a product is baked, the darker it will become. The natural colors range from a pale tan to dark walnut. Wicander explained, “The natural shade variations are part of cork’s visual appeal. The traditional unfinished floors feature all the natural foibles of nature in varying shades of brown and tan, and textures ranging from small granules to burled lumber.” Unlike hardwood, cork does not have graining, so the resulting visual has an appealing monolithic look. “Because most cork floor patterns are non-directional, design versatility and increased installation pattern freedom are great selling factors,” said Helton.

The newer generation of cork floors include enhanced colors and tints for a trendier look. Because cork is essentially a wood product, it can be stained with any recommended wood stain. The urethane finishes also offer variety, ranging from light to medium to dark. Mary Pingor of Wicanders said its commercial Cork Master line has 22 colors, ranging from natural to trendy. “Ruby is very popular now and is being used in a lot of places such as libraries that like rich color. We also have a beautiful dark brown that is unique.” In comparison, she noted the Ipocork residential Corkloc floating floor line has six standard colors, with nine custom colors available. Although the natural shades in the tan/brown family predominate, more stains and tinted PVC coatings were seen at Surfaces this year.

Some companies FCNews spoke with see this as a contemporary growth trend, but others felt the staining characteristics of cork weren’t as good as some other materials, and recommended sticking with the traditional colors, at least for now. Tile Forms When most people think of cork, they picture the original cork floor tiles. These square, modular tiles come in thicknesses that range from 3/16- to 5/16-in. As noted earlier, tiles are made of cork granules and resin binders compressed under high pressure. The size and shape of the granules determine the color and visual of the tile, and offer a variety of looks. WeCork’s Wicander said, “We can use water jet cutting to create beautiful custom designs.” Tiles are sold with either finished or unfinished surfaces.

The unfinished floors are finished on site, usually requiring a light sanding and four to five coats of urethane. Tiles are adhered directly to the floor substrate much like vinyl tile. Some manufacturers recommend water-based adhesives, and others latex-based glues. Still others advocate moisture-cured urethane-based adhesives and dry-lay glues. Regardless, just like any other floor covering, it is important to follow both the floor and adhesive manufacturers’ instructions for compatibility with the cork floor, the substrate, and for warranty protection.

Tile floors can be installed D-I-Y if you have installed tile floors before, or by professionals. According to Natural Cork’s Erramuzpe, “Anyone who can install a vinyl tile floor can install a cork tile floor.” There are also varying qualities in the compressed product. Arcobel’s Helton noted, “Our product uses no fillers. Fillers drive costs down, and can make the product more dense, but they can also compromise some of cork’s natural benefits.” Subfloor preparation must take into account that cork is resilient. Any imperfections or bumps will “telescope” through tile flooring up to the surface. Subfloors should be level or leveled before installing any cork tile.

Although cork is a natural product, tiles should be square and not warped. “This is another good quality check,” said Rob McKee of Expanko Cork. “The squareness and flatness are key factors in a successful installation.” Some companies, such as Expanko, sell complete installation systems including the cork flooring, the adhesive and the installation trowels. Cork planks or strips differ from tiles in shape, but not construction, and need to be adhered to the floor like a tile. There are tongue and groove and “click” varieties. While these floors can be D-I-Y installations, most mills state they are best installed by professionals because of the characteristics of the cork and adhesives. (Editor’s note: Next issue we will look at more of the different types of cork floors available.)