An early Eichler sales brochure summed it up this way: "One of the luxury features of an Eichler home is the cork floor... (It is) durable, easy to maintain, and easy on the feet; and its rich, natural tones add warmth and elegance to a room. Properly installed and properly maintained, it is virtually indestructible." Cork floors have an impeccable heritage: Frank Lloyd Wright used it in his iconic Fallingwater house.
For Eichler owners craving a warm, natural flooring surface, cork seems to fit the bill. But if it's not installed right, it can lead to headaches down the road. While the popularity of cork flooring is increasing among Eichler fans, it's still not an easy material to source and have installed properly. Many flooring stores don't sell it, and installation is tricky, even for a pro.
Proper surface preparation is critical. A clean, level concrete or plywood sub-floor is required. Don't install cork over any type of old flooring. Any irregularities in the sub-floor surface can show up after the cork tiles have been laid, so all irregularities have to be taken care of in advance. After he has removed the old flooring materials and hand-scraped the surface of the slab to take off any high spots, expert installer Perry Cordova, one of our flooring resources, uses a very thin (about 1/16 inch) skim coat of Ardex "Feather Finish" cement-based underlayment to smooth out the floor. The skim coat also serves to cover over and seal in old adhesives, and avoid the mess that machine sanding the floor would inevitably create.
Although cork has insulating properties, cork floors do not seem to adversely affect radiant-heat systems. After all, Eichler himself used cork tiles liberally in his subdivisions. Unlike in the '50s, there is now a choice between floating cork-floor panels and cork tiles glued directly to the floor. A floating floor will be significantly thicker than thin tiles, offering more resistance to radiant-heat transmission. In addition, it is noisier to walk on, and many homeowners prefer tiles for that reason. What's more, if a tile becomes damaged or a section of tile needs to be removed to repair a radiant-heat leak, tiles are easier to remove and replace than floating panels. Manufacturers of cork floating floors specify that a 6 to 8 mil plastic film "vapor barrier" be laid down between the sub-floor and the cork. Larry Wagner of Anderson Radiant Heating claims that plastic films will definitely make radiant-heat leak detection more difficult, given that helium leak detectors are the method of choice for pinpointing leaks in radiant tubing.
There are many size and style choices with cork tile. While Eichler used 12-inch square tiles, modern day homeowners often follow Eichler interior designer Sue Olson's advice to go with the slightly more expensive 24-inch square tiles. "Larger tiles mean fewer lines and a less busy look," says Olson. Some manufacturers also offer a range of rectangular dimensions. Tiles are available in a variety of shades, from quite light to very dark; and even in patterns, though Eichler purists will strive for a uniform, even look. Modern tiles start at 3/16 inch (Eichler used 1/8-inch thick tiles), and thicker tiles are available, but there seems little reason to use them, and they cost more.
Protecting a cork floor is the key to its longevity. While tiles are available unfinished, waxed, or varnished with a polyurethane sealer, Olson only uses the varnished variety, and recommends that after they are laid, two additional polyurethane coats be applied to seal the seams. Cork is a resilient material, yet pads should be placed under sharp furniture legs or other objects. It is not easily dented or marked, but if not sealed properly, staining may occur.
Like other natural materials, including wood and bamboo flooring, cork will fade when exposed to sunlight. Interior designer Patsy Zakian-Greenough lays it on the line for her clients: "Cork will always fade to a certain degree, and you have to be prepared for that." Generally, fading is more noticeable in the darker shades of cork. In part, it occurs due to heat and visible light, but the principal culprit is in the ultraviolet part of the spectrum. Fortunately, UV-blocking window film is widely available, and also can include varying degrees of reflectance to visible light, if desired. If cork is used anywhere near a window, it is highly recommended that an appropriate window film be applied. Of course, window film offers other advantages to Eichler owners with walls of glass, as it can reduce solar heat gain, cut down on glare, and make original un-tempered glass safer around children and in earthquakes. Sun-Chek offers film in 72-inch widths.
Zakian-Greenough points out a benefit of cork that won't be full appreciated until after it is installed. A client of hers who was hard of hearing found that changing a hard floor surface over to cork made it was easier for her to have conversation in her kitchen. The cork absorbed sound better, resulting in fewer acoustic reflections.
Properly applied and protected, cork is a marvelous floor surface that fits perfectly with the Eichler style, and with proper care and maintenance will last for decades.