What Kind of Sub-Flooring (Substrate) is Needed?
Cork tiles can be installed directly over concrete or plywood sub-floors and over un-primed drywall.
Plywood substrate must be clean and free of all adhesives, paint, grease, oil, dirt and other foreign matter. All fasteners must be recessed from the surface area. All seams and voids can be flashed with cementious patching cement only. (Example: Ardex Feather Finish). Never use a gypsum-based product. Plywood should be installed within specified trade practices. Deflections of no more than 1/8″ in 10 feet should be kept. Plywood should be secured via staples and glue. Nails and screws have a tendency to creep up after some time passes. The use of a self-leveling cement works best, giving a truly leveled floor.
Cement or Concrete substrate:
Cement or concrete must be cured, free of paint, oil, dirt, grease and foreign matter, salts and alkaline, moisture content of less than 2 lbs. per square foot. Cement or concrete must be troweled smooth with a cementious patching cement, free of all voids and nubs. Best results are achieved with a self-leveling cement with deflections of no more than 1/8″ within 10 feet. In both cases, the sub-floor must be smooth, clean and free of any bumps or cracks. Any unevenness will show through the surface of the cork floor. Be sure the floor is swept and vacuumed clean before starting the installation. More technical subfloor information is available.
Can I Install the Cork Tiles over other Floor Surfaces?
(Ceramic Tile, Wood Parquet, Vinyl Tiles, or Carpet)
No. If you have carpeting, vinyl, sheet vinyl, rubber etc., it will need to be removed and either the floor will need to be sanded until smooth or easier, a new plywood sub-floor be installed. (For example: Multi-ply plywood comes in sheets of 48x48x1/4″) The problem exists with the previous adhesive residue in the substrate. The new adhesive will not adhere to such a condition. Best results: use an all purpose type of adhesive and glue and fasten the new plywood in place. Follow the section concerning “plywood sub-floors”. If you have ceramic or stone tiles and they are secure and not loose, float a cementious patching cement over tiles making the surface free of all deflections, grout lines and tile cushioning. The sub-floor must be flat and smooth and free of all paints, dirt, oil, grease and other foreign matter.
Moisture Problems in Sub-floor
You can buy a moisture test kit, known as a calcium chloride test. The moisture reading for installing cork flooring should be at or below 3#/1000ft over 24 hrs. Of course a moisture test tells you the moisture levels only at the time that you do the test. If you want to create a vapor barrier for a damp cement subfloor, you need to purchase Visqueen (plastic) in 4-6mm thickness or use a product like Laticrete. Lay out the Visqueen covering the floor and overlapping the seams by a good 6″. Then tape the seams. Additionally, when you get to the walls, run the Visqueen up the wall about 6-8″. On top of the Visqueen, use a self-leveling cement, approx 1/2″ in thickness. The self-leveling cement will hold the plastic in place, maintain the vapor barrier and give you a nice flat, smooth floor to work on. You can trim off the excess Visqueen at the walls where it extends above the new cement.
Can Cork Floors go over Radiant Heat?
You can install cork tiles over hot water radiant heat (but not electric) as long as the surface temperature does not go above 84 degrees. Because of its insulative properties, the cork will be slower to warm up and slower to cool down that other materials with higher conductivity. However, cork is naturally a warmer floor than any other material except carpeting. At the time of installation, you should have the heat on for 3 days at a warm temperature with the tiles unpacked to allow them to acclimate before installing them. The cork tiles will contract when in contact with a heated surface as well as in dry environments so you’ll want them to do this as much as possible before you glue them down. You want to be sure to use sufficient adhesive also.
Can Cork Tiles be Installed over Vinyl Tiles? Can it be used with Access Flooring?
There are many types of access flooring, most of which the panels screw down. Some have a raised lip around the perimeter of the panel (at a specific height depending upon the floor covering to be used). In either case, surface mounted screw heads will be seen flush with the cork. Floating floors are an interlocking system that engages all 4 sides and not readily used for easy access to raised floors.