With multiple floor covering types on the market, a one-size-fits-all underlayment system is just not possible. From carpet to tile, laminate to stone and hardwood to ceramic, each floor covering and installation has its own underlayment specifications and needs, and knowing exactly what those are can determine whether an installation is a success or failure.

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A Solid Foundation

“Underlayments can be viewed in the same way as foundations are viewed in a building—they are never seen, but they play an essential role in the performance of the floorcovering they support and they must last for the life of the building/floor,” said Duonne Erasmus, director of InstaFloor NA. “Always install the best-performing underlayment possible (do not skimp on the foundation). It’s all about functionality, durability and performance.”

According to Steve Taylor, director of technical and architectural marketing for Custom Building Products, there is not one overarching solution when looking for an effective floor underlayment. “With so many floor covering types and so many membrane and underlayment options, it’s critical that the installer understands the challenges of the project, the requirements of the floor covering product and the expectations of the design professional and end user.”

Before selecting an underlayment, installers and contractors must first prep the surface and start with a proper foundation, and when it comes to flooring, that foundation is the substrate.

“Surface prep, surface prep, surface prep—I cannot overemphasize how important proper surface prep is to the successful installation of the entire flooring system,” said Christopher Brana, product manager, Laticrete.

According to Taylor, when evaluating the substrate, questions that should be asked at the jobsite include: “Is the substrate flat? Does it require waterproofing? Is weight a consideration? Is sound reduction a goal? Does it require a fast return to service? Is a heavy-duty service rating required? Are there cracks in the subfloor and is crack isolation a consideration when installing ceramic tile?”

Based on the answers to these and any other questions contractors and installers may ask regarding the substrate, the type of underlayment that’s best for the job can then be determined.

According to Seth Pevarnik, director of technical service for Ardex, installers and contractors should base whether they’re going to use a trowel-grade or a self-leveling underlayment on what the substrate actually needs. “You’re looking at what the substrate is and what is needed to make that substrate smooth for finished flooring,” he said.

Another reason to consider the substrate first is not all substrates can accept all underlayment and not all flooring is compatible with all underlayment products. With this in mind, narrowing down the specific type of self-leveling or trowel-grade underlayment is the next important step to creating a proper foundation for a successful flooring installation.

“Once you decide whether you need a self-leveling or a trowel grade, there are different levels of each of those materials,” explained Pevarnik. “You may have self-leveling that can go over any substrate, go up to any thickness and you can put floor covering on it in 16 hours. You’re going to pay a premium price for that self-leveling because it can do pretty much anything—but you may not need all those bells and whistles. At that point, the contractor will fine-tune what type of self-leveling they need and go to a scaled-down technology [that fits the project] and spend a little less money.”

Jeff Johnson, MAPEI’s business manager for floor covering installation systems, noted, “There are no specific requirements for which type of self-leveler a contractor should use with different types of flooring. The real drivers are the amount of money available to do the project, how quickly the job needs to be completed, whether structural issues are in play and how much traffic will pass over the floor. Price, speed, density and compression strength are the four attributes that drive leveler prices.”

Additionally, when selecting an underlayment, it is important that the underlayment is not only compatible with the substrate but with the floor covering material and the environment where it is being placed.

“Contractors should consider the needs of the finished space and ultimate use,” said Rich Willett, USG’s director, tile and flooring substrates and specialties division. “For example, if the area is susceptible to moisture both the finished flooring and underlayment should be able to withstand it, such as ceramic tile and cement board.”

Avoiding Errors

Failure to properly prepare the substrate or selecting the wrong underlayment can lead to disastrous consequences. “Selecting the wrong underlayment for the project can lead to lippage, cracks, efflorescence and water intrusion issues in the ceramic or natural stone tile assembly,” said Taylor.

He added, “Without the proper preparation of a substrate through the use of the right membrane or underlayment, floor covering products such as tile and natural stone are subject to increasing opportunities for stress and ultimately failure. The proper underlayment makes a significant difference in the aesthetic appearance and longevity of the floor covering material.”

Johnson echoed those sentiments. “When it comes to self-leveling underlayments, proper subfloor preparation is essential. Contractors need to make sure the substrate is clean and meets the required surface profile for the product. The substrate must be primed in virtually all cases before a self-leveling underlayment is applied. The SLU must be mixed properly and applied within the parameters of the product’s technical data sheet (i.e., proper powder-to-water ratio, proper mixing temperature and proper mixing time).”

User error often plays a large role in the improper installation of underlayment products, according to manufacturers. However, by simply following instructions, not cutting corners, using recommended tools, consulting the manufacturer of the system when needed, and undergoing essential education and training, contractors and installers can potentially avoid these issues.

“Follow the instructions,” said Brian Petit, vice president of operations for NAC Products. “Too often, time requirements trump installation instructions. Time is money and shortcuts can save time and money upfront; however, shortcuts can be very costly down the road if the installation fails and it is determined the instructions were not followed properly.”

Jack Boesch of MP Global Products shared an example. Although some underlayments install with the vapor barrier side down, MP Global Products’ QuietWalk underlayment for floating laminate and wood floors is designed to install vapor barrier side up to be most effective with the company’s built-in Moisture Management System.

Further, Brana suggests contractors and installers always work with well-established underlayment companies who provide contractor training, offer reliable and knowledgeable technical support (onsite, online and by phone) and can demonstrate proven results with their products. “Build relationships with sales and technical representatives that can assist with onsite needs and demonstrations. Also, continue ongoing education and training to keep up with the latest trends, techniques and developments in underlayments.”

Pevarnik echoed those sentiments. “Taking advantage of manufacturer training would be a big tip of mine. We’ve been big on training for 40 years, so that everyone knows how to use the products and be successful.”

The Latest Underlayment Systems

Contractors and installers’ demands for products that boast improved performance and benefits have led to the evolution of underlayment systems.

“Contractors and installers demand products that meet their requirements, such as workability, flowability, adhesion, coverage, cure time, ease of use and installation, longevity and warranty, time and cost savings, and overall performance,” said Brana. “There are varieties of underlayment products in a very competitive market that address key features and benefits for contractors and installers to choose and purchase to address their needs. It is important for underlayment product manufacturers to keep up with contractor or installer needs and requirements as part of their product development and improvements.”

According to Johnson, “MAPEI has four new products that address special needs for self-leveling underlayments. Novoplan SP (standard performance) is an economical solution, Ultraplan QuickTraffic is the speed-set solution, Ultraplan Lite addresses the density issues and Ultraplan LSC is a different way of doing skim coating, providing greater compression strength than traditional skim coating. (Visit www.mapei.com to view details about these products.)”

J. Alex Keene, product manager for Dependable, added, “Underlayment technology largely evolved due to our greater understanding of flooring failures.”

Products available in the underlayment market include USG’s lightweight foam panels that can offer water resistance and exceptional tile bond while shortening installation time, along with the company’s cement boards, fiber-reinforced panels and cement coated glass-mat panels, according to Willett.

To lessen the possibility of user-error that can occur when contractors and installers have to mix products themselves—and potentially alter their chemistry—manufacturers are also creating more ready-to-use kits.

“We have a self-leveling product that features a latex additive, so you’re not mixing in any water,” said Pevarnik. “It’s a gallon of latex and one bag of material. It’s increasing that forgiveness factor because the contractor doesn’t have to measure water.”

For MP Global Products, a push for sustainability has led to the evolution of its underlayment portfolio, Boesch stated. “Our most popular underlayments are manufactured primarily with recycled content, and are also certified by a third party as Indoor Advantage Gold, meaning they are a contributor to clean air with no off-gassing or Volatile Organic Compounds (VOCs). This is huge with so many allergies that are often attributed to building materials in your home.”