Custom Building Products’ RedGard  Waterproofing & Anti-Fracture Membrane is applied over a cracked concrete substrate.

Underlayment can be one of the most overlooked aspects of floor covering installation, yet it has a dramatic impact on the performance of the finished floor. To prevent underlayment-related problems, it is important to understand how the type and quality of underlayment used will affect the overall installation process.

Hacker Industries’ Firm-Fill brand gypsum concrete is installed over the company’s acoustical control mat to help limit impact sound transmission in multi-family and residential construction.

A key trend in underlayment product technology is the use of sound- and moisture-control properties, along with crack isolation. Often, manufacturers are combining one or more of these technologies into one system.

However, when choosing an underlayment product including sound reduction characteristics, it is important to consider sound transmission levels refer to the installed system, not just the underlayment components.

“There has been a lot of underlayment manufacturers and brands touting extremely high acoustical test scores that have more to do with a multiple-layer subfloor assembly than the underlayment by itself,” said Jack Boesch, MP Global Products marketing director. “The ‘Delta’ test gives a much truer representation of how an underlayment performs acoustically without the help of beefed-up assemblies.”

Underlayment technology is also transitioning to thinner, easier-to-install products. “The latest trend in sound control and in underlayment is in two directions – thin and code compliant and high performance in the thinnest application,” said Jim Keene, president of Keene Building Products. “That has always meant products a quarter-inch thick in wood frame applications where the typical installation includes a thick gypsum concrete underlayment for fire purposes. With today’s products, the system is a 3mm sound mat made from entangled net to limit touching and air pressure, and a 0.75” underlayment.”

Gypsum underlayment is poured over Keene Building Products’ Quiet Qurl sound control mat.

When calculating the cost of underlayment products, it is important to take into consideration factors such as ease-of-use and working time. “Cost-efficiency does not refer to the lowest bag cost, but the cost savings when the project is dollarized to include the use of less product,” said Hendrick T. Goller, ARDEX Engineered Cements & The W.W. Henry Co. marketing director. “Because coverage rates are better, time savings on labor and moving to the next phase are quicker.”

Another important trend in underlayment is the incorporation of green content and other recycled building materials, an important consideration when specifying products for LEED building projects. In addition to using recycled materials such as rubber tires to produce underlayment products, these are also being recycled into consumer products. For example, Starline Products recently introduced the Eco Reef Sandal, made from recycled carpet pad.

“Certainly the overall drive to more sustainable and healthier interior products has had an influence on the technology developments in underlayments,” said Drew Holland, Healthier Choice’s marketing manager. “Low odor products with very low off-gassing that are made with renewable components are being adopted or even demanded with increased frequency. Green and healthy is no longer nice to have; it is the ante for participation in the underlayment business.”  

“When trying to achieve a green floor system in any project, adding a more sustainable floor underlayment system provides significant advantages,” added Kerry V. Hacker, vice president of Hacker Industries. He noted that products including gypsum concrete floor underlayments can help contribute to LEED points.

“Green content is increasing in demand every year,” noted Ryan Brausa, product manager for Custom Building Products. “So far, consumers seem less willing to pay additional for recycled content underlayments, but soon underlayments will need to contain recycled content to even be considered in the purchase decision.”

Looking forward, underlayment manufacturers said they will continue to refine existing product categories, as well as combining existing products into streamlined, integrated systems.

Ardex K 15 Premium Self-Leveling Underlayment being installed over a concrete substrate prior to the installation of vinyl flooring.

“We are working on what I call ‘composite technology,’ combining more common materials to make floor and wall systems perform at a higher level,” said Keene. “We have done extensive work with fiberglass composite products as separation layers with our entangled net products. They act to add strength when properly designed with pourable underlayments. Additionally, we are working with ‘high loft’ fabrics.” These types of materials are incredibly compressible and can be engineered in various weights, thicknesses and compressibility, according to Keene.

Steve Bjorklund, USG Corp. director of marketing performance for its substrates division, noted that new products should be tested before they are brought to market. “Whenever new technologies are introduced in the market, it is important to verify that they have been tested and meet applicable industry performance standards published by ANSI, ASTM, and the TCNA Handbook prior to using,” he said.

USG Corp. Fiberock Aqua-Tough Tile Backerboard Panels are for use in wet areas, including tub and shower surrounds.

With so many underlayment products to choose from, it can be difficult for retailers to choose the best underlayment product for a given application. However, recent industry initiatives to clarify industry standards are simplifying the selection process.

“Once upon a time, retailers had to carry multiple underlayments to go with each of the multiple flooring brands they sold,” explained Boesch. “Some laminate brands threatened to void warranties if their floor was not installed over their own underlayment. In legal terms, this is called ‘tying’ and is akin to voiding the warranty of a car for changing tire brands. Now that the laminate manufacturer members of NALFA [the North American Laminate Flooring Association] have set industry standards for underlayments, retailers should be able to stock fewer underlayments and choose reputable products that can be used universally for all their flooring brands.”

In addition to the information provided by manufacturers, retailers can also obtain product performance data from GREENGUARD and the U.S. Green Building Council, which administers the LEED program.

“Independently certified advances in underlayment technology such as a GREENGUARD certification of indoor air quality gives the retailer a substantiated feature set to confidently up-sell his customer,” said Holland. “Such qualified features and benefits are replacing the vague marketing bullets that have dominated in the past.”