Wood Subfloors /
The minimum recommended thickness for underlayment panels is 1/4″ (6.4 mm), smooth to prevent telegraphing, resist indentation, should not contain solvents or surface voids. Preferred underlayments should have the APA trademark. Multiply and tecply underlayments have been approved as is APA – AC/BC EXTERIOR. Products such as OSB, Chipboard, Flakeboard and Masonite are not approved. The subfloor over which the underlayment will be installed should be smooth, dry, properly fastened and free of joint swelling, warping or delamination.
Allow panels to acclimate to environmental moisture conditions. You’ll need to glue and staple the plywood down. All seams and voids can be flashed with cementious patching cement (example: Ardex Feather Finish). Next sand across the joints to the width of one foot on either side so the plywood seams don’t show through. Globus Cork Inc. does not warrant underlayment performance.
Treating Existing Ceramic
If you have ceramic or stone tiles, be sure the tiles are solid, not hollow and that there are no voids. If you have loose tiles, you’ll need to remove all the loose ones. If the tiles are secure and not loose, then you can float a cementious patching cement over tiles. Do Not use DashPatch or a gypsum-based product. Only a cementious product will be strong enough to stand up to our adhesive.
You can also use a self-leveling cement to produce a flat surface, making it free of all deflections, grout lines and tile cushioning. If you use a self-leveling cement such as Ardex, be sure to let it dry several days as recommended by the manufacturer. Once the floor is dry, scrape any bumps that you can see. The sub-floor must be flat and smooth and free of all paints, dirt, oil, grease and other foreign matter. Remember that the cork tiles are only 3/16″ thick and any underlying imperfections will telegraph through the tiles.