How to Prepare a Subfloor for Glue Down Cork Flooring
When it comes to glue down cork flooring, it is necessary to have a subfloor that is free of dirt, debris, grease, and anything else that could prevent a good bond. Before you prepare your subfloor, you need to know what type of subfloor you’ll be installing on top of. Here are commonly used types of subfloors:
- Cement floor screed
- Anhydrite or plaster screeds
- Mastic asphalt
- Chipboard and plywood with tongue-and-groove joints
- Ceramic or natural stone tile floors
- Screeds with underfloor heating
To achieve a lasting bond between the subfloor and cork floor, a properly prepared subfloor must have the following elements:
- The subfloor must be structurally sound.
- The subfloor must be clean. The surface, therefore, must be free of oil, grease, wax, dirt, asphalt, curing compounds, latex and gypsum compounds, dust, paint, or any contaminant, which may hinder a good bond. For existing wood floors, use a paint or varnish remover, and then scrub with tri-sodium phosphate. In case of tough stains, paint, or hard residues, you may have to machine sand the floor. Once this procedure is done, the floor must be washed, rinsed, and allowed to dry.
- The subfloor must be level and flat to 3/16″ per 10-feet radius. Additionally, the subfloor should be smooth and free of all bumps and imperfections. If the subfloor is uneven at any point, it will definitely show on the surface of the cork floor. Existing wood floors must be leveled and all cracks should be filled with wood filler or finished plywood. In some cases, existing floors can be covered with 3/8″ plywood. Make sure the plywood has both its sides finished and is secured firmly. This will help you make sure the subfloor is even. Later, make sure to vacuum the room.
- The subfloor must be protected from moisture.
- Cork tiles can be installed directly over concrete subfloors. But make sure the concrete is smooth and dry. Concrete floors (either new or existing) must be leveled with latex fill. Also, prime it with the standard concrete primer. The floor can also be sanded later to ensure uniformity.
- Concrete must be fully cured, for at least 60 days. If the concrete slab is not level, grind down high spots and fill low spots with leveling compound. Do not install on concrete unless you are sure it is not prone to moisture seepage.
- The moisture content of a wood subfloor must not exceed 12%, while concrete moisture content must not exceed 3 lbs.
- Wood subfloors must be dry and well secured. Nail or screw every 6″ along joists to avoid squeaking. If they’re not level, sand down high spots and fill low spots with an underlayment patch.
- If you are installing cork flooring on existing vinyl or other smooth surfaces, ensure the adhesive bonds the two surfaces strongly. If you’re unsure, seek advice from a professional as to what products to use in your given situation, and always read the labels of the products you buy. Always follow the instructions carefully.
- Cork floors are not recommended to be installed at below grade locations unless necessary precautions are taken to prevent moisture penetration through the subfloor. It is often necessary to ensure that an efficient moisture barrier is installed.
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