Subfloor preparation

It is all in the preparation


With correct subfloor preparation, your Karndean flooring installation will have a perfect finish and long-lasting result to complete your project. As well as fitting within the BS8203:2017 guidelines, we recommend the following steps.


Prior to any installation, it is important to check that the subfloor is level, free from adhesive residues, dust and debris. To ensure a smooth finish to all solid subfloors, it may be necessary to apply a minimum 3mm layer of a smoothing and levelling compound.


For wood based subfloors, we recommend overlaying the existing floor with a minimum 5.5mm flooring grade plywood (as outlined in Contract Flooring Association’s Guidance). Plywood joints should then be smoothed with an application of skim coat or a full coat of a suitable smoothing compound.


Is your floor dry enough to cover?


It is vital to check for moisture and establish if your subfloor is dry or damp.


  • With loose lay and rigid core formats, your readings should be below 95%RH (Relative Humidity) as our looselay and rigid core formats allow the floor to be installed much earlier in the project. They are ideal when the subfloor is still drying out in new build accommodation and community living schemes.
  • For gluedown, subfloor moisture readings must be below 75%RH. If readings are higher, a surface applied damp proof membrane may be required.

Once the subfloor has been appropriately prepared and a smooth surface achieved, you can confidently begin to install another stunning Karndean floor.


View our gluedown, loose laInstallation Guidelinesy and rigid core installation guidelines here. Do you have a question for our technical team? Call us on 01386 820104.