All flooring manufacturers specify that concrete floors or screeds need to be clean, dry, sound and free of contamination prior to installing self-levelling screeds. Most final floor coverings whether epoxy, vinyl, LVT’s, LVP’s, carpeting, natural wood or laminates will require a self-levelling screed for one of the reasons below.
Self-levelling screeds are generally specified when the sub-floor is either not level, smooth or flat. Generally “level” implies that the floor is level from one end of the area or room to the other. In most cases this is very uncommon and only achieved through laser-level application and specification. Even a class 1 floor may not be level throughout. Smooth implies that the floor has no surface imperfections, lumps, bumps, holes or surface contours. Flat implies that the floor is flat over a specified distance. A floor can be flat but not level, level but not smooth and smooth but not level.
Generally all of the above requirements address aesthetic issues or concerns. In most cases level and smooth are the more critical concerns. For these reasons self-levelling screeds are specified. Self-levelling screeds are designed to smooth and level out sub-floors. Self-levelling screeds cannot address the issue of levels. Due to the nature of the product self-levelling screeds will constantly level out following the existing level of the sub-floor. For the correct installation tools contact https://floorshq.com/rox-tools/application-tools/
Existing sub-floors require correct preparation to remove contamination from oils, chemicals, glues and bitumen. Grinding of the sub-floor is generally required to remove these contaminants and to key the existing surface for proper adhesion. https://floorshq.com/rox-tools/floor-preparation-tools/
The long-term success of a self-levelling screed will depend on whether the underlying sub-floor is structurally sound. Self-levelling screeds should not be applied to river sand / cement screeds or concrete floors below 15 MPA. The river sand cement screeds should be structurally sound, and well bonded. All cracks and imperfections should be corrected before applying the self-levelling screed.
The moisture content of all sub-floors should be thoroughly checked prior to apply a self-levelling screed. The self-levelling screed may be able to tolerate a higher moisture content, but the final floor finish will not. A moisture content of 3-5% is required in most cases depending on the final floor finish required. New and improved moisture barrier primers are available today and greatly reduce floor failure, but should be used as a precaution and not as a cure. https://floorshq.com/rox-tools/measuring-tools/
All of the above variables play a role in the successful application of a self-levelling screed. Always choice a specialist flooring contractor for a successful installation.
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