When arriving at the jobsite to discover a substrate that is far from ready to accept a floor covering, installers have several tools in their arsenal to get the substrate in shape, including self-leveling underlayments. Some may think there’s not much to the product – just mix and pour and let it do its thing – but that’s a misconception. Self-levelers have been improved with new technologies, more green content and special formulations that let them go down quickly and make them more forgiving, even on fast-track projects.

New technologies. Among new technologies in self-leveling underlayments is a greater reliance on green content. According to Phil Ciesiulka, USG business development director, his company’s Durock EcoCap features 75 percent recycled content in the cement binder and requires up to 50 percent less water than competitive products. “The combination of conserving water along with the performance of the product should be something interesting both to building owners and the architectural community,” he said. “It’s also strong in the sustainable features that people are looking for.”

USG is also in the process of developing new finished floor systems to be used with the company’s underlayments, including topical staining, integral coloring and polishing. Ciesiulka noted that some of these products will be debuted next year at World of Concrete and Surfaces 2014.

Ciesiulka said there is a common misconception that gypsum-based products are weaker than traditional cement products. “That feeling probably dates back to the ‘70s, when gypsum cement had compressive strengths of 1,200 to 1,500 psi at best. However, we’ve made significant advances since then, and some of the products in our portfolio can handle between 7,000 and 10,000 psi. That assumption of gypsum-based products being weak and chalky just isn’t the case today.”

Of course, no underlayment will function correctly if the substrate isn’t properly prepped first. USG recommends shot-blasting or otherwise mechanically profiling the surface before the pour. “Self-leveling underlayments are not a cure-all. These products won’t stop or eliminate active cracks or other problems. The product you put on top of the substrate will only perform as well as how you prepared that substrate.”

Joe Hostler, Dependable LLC director of sales, said many people think that gypsum-based products are susceptible to mold. “Our products have mildewcides in them and do not mold. The old prohibitions are based on products from 30 years ago; the industry has moved on quite successfully with millions of feet installed.”

Schonox recently unveiled two new synthetic gypsum self-leveling products: AP and APF. After the surface is primed, AP is designed to be poured over any existing substrate without the need for shot-blasting or scarifying, according to Enos Farnsworth, HPS Schonox president. The company’s APF underlayment contains a reinforced fiber that can go over critical substrates including rubber, he added.

Farnsworth noted that these products were designed to fill the need of low-prep products for the renovation market. “These products were engineered to be used in renovation because that market is growing so fast,” he explained. “There is not as much new construction out there, and there are so many advantages to going in and renovating a substrate as opposed to building a new one.”

Ken Barnum, LATICRETE underlayments product manager, is also seeing an increasing need for products that can be used in fast-track scenarios. “The evolution of this entire category will revolve around going in earlier and earlier, especially in hospitals and schools where time is critical. It may evolve even further by working closely with the concrete guys and developing lower-moisture concretes.”

He also says it is important to test for moisture and address any problems prior to applying any type of self-leveler. “The ability to test moisture conditions accurately after the installation of self-leveling underlayments does not exist,” he stressed. MAPEI offers a range of self-leveling products, including a low-prep formulation called Novoplan Easy. “Not having to shot-blast or surface profile can save some time and cost,” said Jeff Johnson, MAPEI product manager.

One potential avenue for the next big breakthrough in underlayments will be for ones that can be installed in what Johnson calls uncontrolled environments. “That means a self-leveling material would be applied when the plastic is still on the windows, and the HVAC isn’t running. A contractor could prep the floor long before other trades come in.” As for current products, he sees the biggest application error in the form of overwatering the product. “These products are balanced formulations based on certain amounts of water. You definitely don’t want to add too much water, or mix two different brands or even two different formulations.”

Applying the product. Another common misconception is that self-leveling products will always find their own level without any help. “Many believe self-leveling underlayments can be poured and ignored,” said Pat Cunningham, ARDEX Americas technical services consultant. “But there are several steps to installing a self-leveling underlayment, including gauging, raking and smoothing.”

Chas Efird, Bonsal American technical support, echoed those sentiments. “Self-levelers do require raking, which moves the material around to the correct height requirements. Smoothing breaks the surface tension and releases any gases that would prevent a smooth surface.”

Tom Cassutt, ProSpec product manager, added that some people may mistake underlayments for a wear topping, but should never be used for that purpose. “Underlayments are designed to be covered, as opposed to a wear topping that is designed to be walked on. Everyone thinks concrete is concrete, but both of these products serve two very different functions.”

Another common misconception is using fans to circulate air, thinking it will enhance curing. In fact, this practice can damage the self-leveling underlayment, according to Tom Plaskota, H.B. Fuller Construction Products technical support manager. “Greater airflow can pull moisture from the self-leveler and cause minor surface cracking.”

Manufacturers are hard at work developing products with faster curing times. Other advancements Plaskota sees include self-levelers that can be used over “a broader range of substrates, such as metal surfaces and concrete with specific types of coatings or sealers. Advancements in technologies have also enabled the development of formulations that no longer require lath over some wood substrates.” 

Alan Kin, sales/technical for Texas Cement Products’ Texrite brand, said the expansion of products in the self-leveling segment has allowed manufacturers to reach into new areas of the market. “Manufacturers are expanding product lines to more than just one grade or type of self-leveling.”

When using a self-leveling underlayment, be sure to follow instructions for proper surface prep, including priming, he added. “Paints, overspray, old glues residue, cutback adhesive residue, sealer or curing compounds continue to be the break point of delamination and failures. All underlayments and especially self-levelers rely on a clean and uninterrupted bond interface to perform correctly and maintain durability.”