How to Ensure a Successful Self-Leveling Underlayment Application

“Self-leveling underlayment” (SLU) is an euphemism. Although this kind of product is extremely useful but it is an experienced and skilled installer to achieve the highest level of performance. Be sure to follow these steps to avoid problems with your self-leveling installation.


Select the right product for installation: 

Know the environment in which you will install it and become familiar with the applicable ASTM standards for the strength. Commercial flooring that is with a lot of rolling load will require a more durable self-leveling flooring than one that is used in a home with a single family.

It is also crucial to know the timeline of your project and select an item that will fit within the proper timeframe. Certain products might require 24 to 48 hours before installing flooring while higher-end products are able to install a floor covering that is moisture-sensitive within 12 to 16 hours.

Check out the product data sheets to learn more about tensile strengths as well as compressive strength and the strength of flexural elasticity, as for cure times recommended by the manufacturer.

In general there are two types of self-leveling underlayment : conventional and next-generation technology. The primary distinction between traditional and next generation SLUs is their ease of flow and the smooth surface of each one.

Certain installers like the features of the traditional SLUs due to their working characteristics. Others prefer the latest technology due to its high performance properties, and its extended working hours.

The scope of the job will determine the type of technology utilized to install. Traditional SLUs are ideal for applications that require deep fill greater that 3/16″. Modern technologies are great for applications that require less thickness.


Know your substrate 

Most SLUs require the surfaces are solid and stable prior to the installation of an underlayment with self-leveling. For instance, knowing the porosity of your substrate is essential to selecting the right primer. (A simple test using water droplets will reveal the porosity of the surface as per ASTM F3191). It is equally important to understand the composition of the current substrate. For instance: generally, sound concrete requires only one coating of primer. Gypcrete without sealing may require additional steps such as several coats prior to application of self-leveling cement underlayment.


Create your flooring: 

Make sure to cover any gaps, openings on the floor and cracks, and then make sure to install termination dams to avoid any water seepage. Contact the manufacturer of the product to find out the moisture limits of the flooring covering as well as self-levelers and adhesives to determine if mitigation of moisture is required.

If mitigation of moisture is required it must be accomplished prior to the installation of the self-leveling overlay.

Self-leveling underlayment requires the application of primer prior to the installation. In the absence of a primer can cause installation failure. Primer keeps the moisture in the self-leveling layer to facilitate the proper curing. It also acts in the role of a bonding agent in order to make sure that the SLU is properly bound with the substrate. Check the primer label for details on application methods and dilution according to ASTM F3191.

Beyond priming, many self-leveling overlays need that the substrate be free of any contamination which could cause a blockage to bond such as adhesive residues, sealers/curing chemicals such as grease, oil loose or peeling paint, and other substances. Polished underlayment requires epoxy primers or a certain Concrete Surface Profile (CSP) in these instances Mechanical abrasion (shot-blasting) is needed.


Proper water requirement: 

Mix your self-leveling underlayment in the range of water stated by the label. Overwatering can weaken the structure of the underlayment and can cause cracks and dissolving. A white film can appear on the surface of the underlayment that has been cured when the product is overwatered. Inadequate mixing of the SLU can cause it to be hard to handle, and could lead to a lack of flow, cracking or an uneven surface. Mix at least two bags at a time during you mix the barrel to assure optimal efficiency throughout the application process. Additionally, certain SLUs are able to be pumpable. When pumping, particular attention must be paid to ensure an appropriate ratio of water and to avoid overwatering. Follow the manufacturer’s equipment and guidelines when pumping self-levelers.


Temperature of the product as well as ambient temperatures: 

Be sure the temperature in the area is within the manufacturers’ acceptable range. Temperatures that are too cold or hot could affect the product’s performance, such as the longer time for setting in cool temperatures or decreased heal time in hot climates. The humidity and temperature influence the flow, time of work and the set time of the SLU.

In addition it is important to know the temperatures of both the powder as well as the water is also crucial. The product left in direct sunlight as well as in hot area could result in flash setting. When a warm temperature cannot be avoided, mixing it with cold water could aid in overcoming installation problems. To ensure that cold water temperatures are maintained during hot temperatures, make use of bagged or blocked ice inside the water tank.

No matter if the temperature is cool or warm it is important to acclimatize before mixing the substance is the best way to go.


Use only as suggested: 

Manufacturers will specify the maximum thickness of their product. Some products allow the inclusion to gravel (pea gravel) to enhance thickness of pour and others allow the item to be applied in a neat manner. Make sure you choose the correct aggregate size and quantity when you extend a self-leveling overlay within one pour. The use of two separate pours or several lifts will reach the desired thickness without the need for an additional aggregate. When the SLU created by the initial pour has become an accessible surface it is possible to apply the correct primer coat for the subsequent lifting or pour. If the surface is incredibly uneven in areas that have depressions of more than 12 ” in depth (bird bath) You can apply these areas separately to your final coat. This can aid in the process of applying by using the same amount of self-leveling overlay throughout the process. Always check with the manufacturers to find the best product for your needs.


Guard your newly laid underlayment 

Self-leveling and self-leveling flooring should be kept away from flow of air (drafts) throughout the curing procedure (2-6 hours) since they can be cured too quickly, which can lead to cracking. In general, the majority of underlayment aren’t considered to be final wear layers. In the process of curing (2-24 days) they must be shielded from the effects of excessive construction. In the absence of protection, traffic could cause uneven and gouging surfaces. Allow the surface to completely cure to avoid any surface damage prior to flooring installation.

The most common thread among the self-leveling application guidelines: observing and following the instructions provided by the manufacturer. Read labels and data sheets for the product carefully to ensure that the product performs according to the specifications you want.

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