I have been heavily involved in cork floor tile over the past six years since I started my consulting and sales businesses. A lot of cork is being installed these days and when done correctly it’s a beautiful floor. However, I regularly speak with 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. With a little TLC it’s not that tough. Although classified as resilient flooring, cork is more like wood with regard to handling, installation and finishing. 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 am 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, and I have written several times here in “Lets Talk Resilient” about the history of cork, how it is grown and manufactured into flooring. So, let’s talk about putting it down.
Installing cork is different from other resilient products so there are some key things to pay attention to. Cork is affected by 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. 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 to prevent any possibility of damage to the brand new floor. A cork floor needs to be the last part of any construction project. I have seen a lot of beautiful floors get trashed after they are installed, so it needs to go in last.
Cork needs to go over a concrete or plywood substrate. If you’ve read FCI before 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! On wood subfloors, use plywood as the preferred underlayment. Once you have a smooth, dry substrate in a climate controlled space, the tile can be installed.
The adhesive for cork tile is water-based contact adhesive that is applied to the back of the tile and also to the substrate using a short nap paint roller. Don’t even think about any kind of trowel-applied adhesive. Most of the problem jobs I have seen with curling cork tile were traced to trowel-on adhesives with too long an open time. Those adhesives may work well on a variety of flooring materials but it’s tough to get it right with cork and besides, contact adhesive has an outstanding track record. Water-based contact adhesives for cork have been successfully used for more than 20 years so it does not pay to mess around with any other kind of adhesive. Contact adhesive provides an instant bond that holds the tile in place without curled edges. Don Jewell confirmed what I have been told many times before, “Installers experienced with contact adhesive often find it as fast or sometimes even faster than trowel-on adhesives.”
You can save time by coating the tile a day ahead of time. It goes on easily with a paint roller and dries in a half hour or so. While one installer works on floor prep, another installer or helper can set up in an adjacent area to coat the tile. Make sure to cover all the way to the edges! Once the adhesive turns completely clear, it is dry and you can stack the tile up (face to back, not back to back!) or even put it back in the box.
The substrate is coated in the same way as the tile, after the floor is cleaned and cleaned again. Don Jewell explained, “Extra care must be taken to ensure a perfectly clean substrate as there is no trowel application to final “tack” the floor.” Like any other resilient product, any junk left behind will telegraph through the new floor and ruin the installer’s hard work and a paint roller may pick up some debris off the floor, but not anything large. Sweep or vacuum at least twice!
The tiles can be laid snug up to the adjacent tile and set into the adhesive so the tiles are tight up next to each other. It almost sounds like a “zip” plastic bag when you slide it into place. Then, tap the tile with a rubber mallet. You don’t have to hit it real hard – just a firm tap all around the edges and in the center to be sure the two adhesive films are in contact with each other. You can also follow up with a 100-lb roller if you like, but don’t substitute the mallet for the roller – it’s a must!
Another advantage of contact adhesive compared to trowel applied is that the installer can work on top of the newly installed floor and the floor can be walked on immediately. Keep heavy traffic off the floor for a day or so. Sometimes an additional coat of polyurethane is applied after the floor is installed. This needs to be done by someone with experience in floor finishing.
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, professional installers who understand this product can become cork specialists. They will be the ones who get the jobs while others who are intimidated or unfamiliar with this beautiful, environmentally friendly material don’t.