Retailers: Don't Be Afraid of Cork Flooring
February 22, 2008
I often encounter flooring dealers, contractors and architects who are reluctant to work with cork because of past problems or the perception that it is “complicated” to work with. Although classified as resilient flooring, cork is more like wood with regard to handling, installation and finishing. Many of the things I will say here about cork could have the words “just like wood” added. For this column, we’ll cover traditional cork tile as opposed to cork floating floors and vinyl wearlayer/vinyl backed cork tile.
Since 1993, I have been aware of cork flooring and have worked for, represented or consulted for three cork manufacturers, made two trips to forests and factories in Europe and done troubleshooting of many failed jobs. I also just became the chairman of the ASTM task group that will develop a new cork floor tile standard for North America – the first ASTM standard for Cork floors. For these reasons, I am regularly asked about cork, especially traditional cork floor tile.
Traditional cork tile has been around for almost 100 years and comes in two types of construction – veneer and homogeneous. The veneer products have a thin cork veneer on top of a granulated cork backing with a finish on the top. Homogeneous cork is a solid piece of material with the color and pattern all the way through, and a finish on top. Both floors are usually purchased with a factory-applied finish, although unfinished cork that is site finished is another option.
Durability is all about taking good care of the finish, and using cork where it will not be abused and where it will be maintained correctly. Sweeping and damp mopping, and preventing damage from excess liquid, direct sunlight and heavy objects being dragged across the floor equal a floor that will last. However, if the floor gets abused or neglected and the finish wears off, the homogeneous floor can be sanded and refinished just like many wood floors, but veneer cork floors cannot. This is an important point, especially when floors are being specified for commercial use.
Installing cork is different from other products so there are some key things to pay attention to. Cork is subject to changes in dimension due to variations in temperature, humidity, and moisture, so it should not be installed in a building that does not have the heat or air conditioning running, and the product must be delivered at least three days before installing to acclimate to job site temperature. No exceptions! Be sure all the other trades are finished before you start installing the new floor to prevent any possibility of damage to the brand new floor. A cork floor needs to be the last part of any construction project.
If you’ve read NFT and FCI for the past five years you have seen a lot written about the importance of concrete moisture testing. With natural products like cork and wood, it is even more important! Prepare and test concrete according to the manufacturer’s guidelines and ASTM F 710, Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring, and don’t install the floor if the substrate is not dry, flat and smooth! (For more information visit ASTM International at www.astm.org or call (610) 832-9585.)
Adhesive selection and application is another important part of a successful cork installation. Talking to the experienced cork installers in Europe and here in the United States made me a bit old fashioned as far as cork adhesive. The traditional method uses a water based contact adhesive that is applied to the back of the tile and also to the substrate using a paint roller. Because contact adhesive provides an instant bond, this method really holds the tile in place without curled edges. The tile can be coated a day ahead of time, or even at the factory, and large areas of the substrate can be coated at one time. Because the tile is set “dry,” the installer can work on top of the newly installed floor and the floor can be walked on immediately.
An alternative method uses trowel-applied adhesive, which is more comfortable for many installers because this requires only a single application of adhesive on the substrate. However, these are often “wet set” adhesives so only small areas can be done at a time and it is critical to follow the proper trowel notch size and open time. If the adhesive is left open for too long, the flooring won’t adhere properly and there will be curled edges. Plus, you can’t work on top of a new floor that is set into wet adhesive and you can’t walk on it for a good 12 hours or more. For these reasons, the wet set method may not be as “fast” as a lot of people in the floor covering industry think it is when compared to the contact method – even if the installer has to apply the contact adhesive to the back of the tile!
I am convinced that if I had an installer race with one team using contact adhesive and the other using wet set trowel-applied adhesive, there would not be a big difference in time between the two installations, and the contact method might be even faster when you take into account the floor being ready to walk on right away.
As far back as the 1920s, millions of square feet of cork flooring were installed in North America, but cork use fell off as other synthetic materials grew in popularity. For the past 15 years or so, cork has reemerged. As cork flooring continues to grow in popularity, flooring dealers and contractors who understand this product can become cork specialists. They will be the ones who get the orders while others are intimidated or unfamiliar with this beautiful, environmentally friendly material.