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Self Leveling

Self Leveling

Floor levelers are typically used to create a flat, smooth surface on an existing substrate. The name can be deceiving since self-levelers do not level a surface by default. While it is possible to achieve true level with a self-leveling product, it requires pouring with the use of pins set as a benchmark to achieve a predetermined finish floor height. The normal intent of a self-leveler is to raise the height of the surface and provide a smooth and uniform surface finish.

There are various leveling products available, but they generally fall into two basic categories. Underlayments are levelers utilized underneath a finished floor and serve to create the proper height, flatness, and/or bonding conditions for subsequent floor coverings. Overlayments are levelers utilized as finished floor surfaces. Most overlayments can be integrally colored, stained, coated, or clear sealed depending on the end-user’s preference and are applied with a squeegee.

Project Considerations

The type of product used will be determined by the unique requirements of the individual project. Factors such as dry time, compressive or flexural strength, and minimum/maximum application thickness will all be contributing factors in the decision making process.

Most finished floor coverings have specific requirements for underlayments that will be installed underneath their products. If used as a wear surface, most overlayments require a sealer or coating of some type. This would normally be a Urethane Topcoat. As with most floor attached floor systems, self-levelers have moisture and surface preparation requirements that must be met prior to installation. Additionally, substrates with excessive moisture vapor transmission levels may require the application of a moisture control sealer underneath the self-leveler. There are no moisture control systems on the market that can be installed over self-levelers.

Application Process

Once testing and compliance with product and floor covering manufacturer requirements have been met, the installation can begin. Most self-levelers require some type of surface preparation to insure that the surface is clean, sound, and free of bond breakers (consult individual product manufacturers for specific guidelines). Different products have benefits and disadvantages that will make them the appropriate selection in specific situations.

Self-leveling underlayments are a quick an effective method for adjusting the height of an existing floor surface. Since the product is designed to flow and seek its own level, only minimal labor is required to achieve a smooth and flat surface.

Depending on the type of cement technology the product utilizes, subsequent floor coverings can be installed within 24 hours of application. High hydrating cements (also called self-drying) provide the most rapid turnaround while gypsum based products take the longest (7-10 days typically) to dry.

With either product, moisture (water used to mix) must be completely absent from the underlayment prior to floor covering installation. The high hydrating products incorporate technology that rapidly consumes the mix water into the accelerated hydration process. This yields quicker early strength properties and shortened dry (cure) times. Gypsum concrete technology has made substantial improvements recently and has been approved for use with most finished floor goods. Although the products do not dry or gain strength as rapidly as high hydrating products, they are less costly. When quick turnaround is not a priority, newer generation gypsum based levelers can provide value engineering opportunities.

Self-leveling overlayments are similar to underlayments in application and form. The main difference is that overlayments are designed for use as a wear surface when sealed. Increased compressive strengths allow overlayments to serve as finished floor surfaces. Typically, overlayments are of 100% solids in formulation and are available in grey or white. Color can be added while in the plastic state or stains or dyes can be applied topically on the cured surface. Pigmented or clear sealers can be employed to protect the surface from abrasion or contaminant penetration.

Self-leveling cements are susceptible to moisture and require a film forming sealer to provide top-side protection. Substrates with excessive moisture vapor transmission levels may require the application of a moisture control sealer underneath the self-leveler. Overlayments provide designers with multiple finish options which include; monolithic, stained, integrally colored, saw-cut, multi-color, or dyed finishes which are smooth and flat. Generally 30 – 45 mills is the minimum thickness required for an overlayment to be utilized as a finished floor/wear surface.

Benefits and Limitations

All floor systems have specific requirements for successful installation. It is important to verify that the product manufacturer’s written guidelines govern the installation process. Adherence to instructions is critical for maintaining the manufacturers’ warranty; neglecting them will almost certainly void the warranty. Proper product selection based on end use, appropriate scheduling with other trades, testing and compliance to product moisture requirements, and installation per industry Best Practice methods are the keys to a quality flooring installation.

Self-levelers are excellent for creating a uniform flooring surface. The design of the product facilitates the consistent uniformity of surface height and finish. However, the self-healing and flow properties of the material preclude self-levelers from being used on sloped surfaces. Additionally, almost all self-levelers are rated for interior use only.


Regular maintenance is vital to the long term welfare of all floors. There is no surface available that remains in optimum condition without regular cleaning and maintenance. The floor is subjected to the most abuse in any normal business. Keeping the floor in good condition takes a little forethought and consistent effort. The first key to floor maintenance is preventing as much soil, debris, and potential damaging agents from being introduced to the environment in the first place.

Interior and exterior walk-off mats can minimize the amount of sand, water, and foreign matter that are tracked onto the floor. Limiting contaminants will simplify the maintenance process. Since the self-leveler is beneath the floor system, the maintenance program for underlayments is determined by the finished floor covering installed. Overlayment maintenance is determined by the requirements of the coating or sealer that is applied as the final finish.