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Fitting a Karndean floor

Subfloor Preparation

It’s well-documented that the success and longevity of a flooring installation - particularly luxury vinyl flooring like Karndean - is dependent on the preparation of the subfloor.

To ensure your Karndean installation looks as good as possible, take these necessary precautions:

Remove and Smooth

If you're laying Karndean over existing flooring, be sure it is properly prepared. All waxes or sealers must be removed, and patching/leveling or embossing must be brought to a flatness of 3/16” in 10’. If you are installing where existing floors have been removed, check that there are no traces of previous adhesive residue. Before applying smoothing compound or screeding, check that there are no obvious bumps in the subfloor, simply to ensure a smooth as possible finish.

Check the Moisture Level

LVT products must only be installed on subfloors with moisture levels below 95% relative humidity (RH) per ASTM F2170 or 8lbs Calcium Chloride per ASTM F1869. If your reading is above 95% RH or 8lbs Calcium Chloride, regardless of whether the floor is old or new, it’s imperative to install a moisture mitigation system such as our Kovara MBX.

Wood Subfloors

Karndean does not endorse/approve any plywood product and takes no responsibility for the performance of any plywood selected. We recommend the use of a minimum ¼” (6 mm) Underlayment grade plywood that meets the requirements of the American Plywood Association (APA) or panels manufactured to be used as underlayment for resilient floors, as acceptable for use with Karndean products. It is the responsibility of the installer to verify this compliance through either independent certification or other means. It’s important to remember to follow the underlayment manufacturer’s installation instructions. All fasteners and panel joints must be filled with a cementitious patch and sanded smooth.

Concrete Subfloors

If you’re installing Karndean on either a new or old concrete subfloor, as mentioned, it’s essential to conduct a moisture test to ensure the levels are no higher than 95%RH per ASTM F2170 or 8lbs Calcium Chloride per ASTM F1869. If moisture levels are too high, then be sure to install a moisture mitigation system such as our Kovara MBX.

Get Screeding

Choosing the right smoothing compound is very much dependent on the type of project, its size and timescale. If prepared and installed correctly, this thin cementitious top layer will ensure that your floor will perform as it should. As such, it's important to consider ambient conditions (ventilation, humidity etc.), installation specifications and curing times.  

For further information on subfloor preparation, download our installation guidelines.