Installing a Cork Tile Floor: Preparation Installing a Cork Tile Floor: Preparation
Cork is a natural product similar to wood, and cork tiles and planks will vary in shade or pattern. Although not as prevalent as with wood, cork is subject to minor expansion during periods of high humidity and minor contraction during periods of low humidity. With cork, expansion and contraction can be kept to unnoticeable levels by stabilizing the space where the floor is installed through temperature and humidity control, allowing for proper acclimatization of the product prior to installation, using only approved adhesives, and providing the recommended expansion space.
Preparing the Subfloor
When installing a cork floor, the subfloor must be carefully chosen, as only underlayment grade substrates are suggested for installation of cork flooring. Cork can be installed over concrete on or above grade. Concrete substrates need to be sound, smooth, level, and free from any defects. Any uncorrected irregularities will be transferred through the cork tiles, so all cracks, holes and control joints must be patched with a Portland cement-based compound before installing the flooring surface. Follow the compound manufacturer's instructions fully, and make sure patches are completely dry and well adhered. Use of gypsum based compounds is not recommended due to their lack of adhesion to the backing materials of the cork tiles.
Check the concrete slab for moisture. To test for humidity if you don't have a moisture meter available, tape a 2'x 2' section of clear plastic to the concrete slab, forming an airtight seal. If condensation or discoloration appears on the plastic after 24-48 hours, the moisture content is likely too high for most wood products. To avoid moisture damage to the cork, check basements and crawl spaces to be sure they are dry and well ventilated. For buildings with crawl spaces, it's a good idea to install a ground cover of 6 mil polyethylene sheets, overlap seams 8", and tape the sheets together.
Subfloor primer must be used regardless of the type of subfloor used. These primers can easily be obtained at any home improvement retailer. Pour subfloor primer into a clean paint tray and, using a low-nap roller, apply a thin and even coat of subfloor primer. The subfloor primer must be totally dry before application of adhesive.
Acclimating the Cork
Before you can begin the installation of your cork floor, the cork must be acclimated to the space in which you are planning to install it. Acclimation of the tiles can be done by storing the cork tiles out of the box at the work site for a minimum of 72 hours prior to installation. During storage and installation, maintain temperature and relative humidity at levels consistent with conditions that will prevail when the space is occupied. Heating or air conditioning should be used for an appropriate length of time prior to and during installation. Without proper acclimation, the floor could noticeably expand or contract after installation.
If your home is equipped with radiant heat, or a heat source directly beneath the flooring, your cork floor may gain moisture or dry out faster than in a home with a conventional heating system. Cork floors move as an individual tile and can swell or contract as they respond to changes in heat and humidity. Therefore, joints between tiles could become more visible during heating season. For installation over a radiant heat system, allow the slab to cure appropriately, turn heat on regardless of the season, and leave it on for at least 5-6 days before installation. When using a radiant heat source in conjunction with a cork floor, it's best to keep the maximum surface temperature below 85°F.