Anyone who’s spent more than a decade in the flooring business might say the industry is a lot different than it was 10 —or even five— years ago. And the rapid evolution of a new product category called multilayer flooring (MLF), the super descendant of rigid core, composite core and luxury vinyl tile (LVT), is “hard” evidence of that.

Known for its advanced durability, water resistance and ease of installation, MLF is rapidly taking over the hard surface category. Because of this, installers need to be made aware of the proper procedures for preparing subfloors and installing MLF products.

Subfloor Preparation

Unlike traditional glue-down tiles, MLF products can be installed over imperfect subfloors due to its enhanced rigid core surface. David Altman, director of research and development at Metroflor Corp., said minor imperfections that would normally show through a glue-down vinyl floor can generally be covered by MLF products with minimal preparation. “Some rigid core products will bridge grout joints and do not require floor prep when installing directly over existing ceramic tile,” he added.

Having the ability to install MLF products over blemished subfloors saves installers a lot of time on projects, added Kevin Flannigan, national field services manager at Mohawk Flooring.

“Normally when you glue something down, you have to skin the whole (subfloor) and wait an hour or so for it to dry,” he said. “But with the multilayer floors, you can just come in and install right on top of it [the subfloor], which eliminates a lot of extra steps for the installer.”

Jim Kups, technical manager at Novalis Innovative Flooring, added that although little preparation is needed for installing MLF products, standard pre-installation procedures still apply. “We still want clean, smooth, dry and flat [subfloors] as the basis for criteria,” he said. Otherwise, installing over a rutted surface could potentially break the locking system, Metroflor’s Altman pointed out.

“A floating system installed over an uneven subfloor can create a trampoline effect when walked on,” said Altman. “Too much vertical movement has the potential to cause a locking system to come unlocked or even break the joints.” Fortunately, MLF products can be repaired just as quickly as they were installed, added Mohawk’s Flannigan.

“With a floating product, you can unsnap it, do the repairs you need to do, and then put the same product right back down,” he said. “Versus if I glue down a product…you’re going to have to tear all that out, buy new material and redo it. So it’s a big lifesaver for the installer. Even if he didn’t do it correctly the first time, he’s got another shot at it.”

Water Resistance

Another key feature of multilayer flooring is its ability to sustain in environments that are more prone to moisture, including bathrooms, laundry rooms and kitchens. MLF products also possess the enhanced durability to withstand extreme flooding conditions, an area in which its glue-down predecessors fall short.

“Let’s say I [installed] a glue-down product; once the moisture starts to wick up, the glue is going to become slimy and the floor it going to fail,” said Flannigan. “The difference with (MLF) is that it’s going to float over that floor; water coming up from underneath won’t hurt the floor.”

But installers should still use sound judgment when working in moisture-prone areas, said Len Daubler, hard surfaces technical support manager at Shaw Industries.

“Even if the flooring is not affected by moisture itself, you want to take steps to prevent moisture intrusion from affecting the subfloor,” he added. “Prepare the subfloor in wet or damp areas by using a waterproofing material to protect the subfloor. Additionally, use a silicone caulk around the perimeter where the flooring meets a vertical surface.”

In areas where water may spill on the surface or get under the floor, the perimeter expansion zone should be filled with silicone prior to installing the wall trims, added Morgan Hafer, installation and project manager for Armstrong Flooring.

Most flooring manufacturers will also specify a maximum moisture limit for their MLF products, which is something installers should take heed of when addressing moisture issues. Joe Cea, installation specialist at Congoleum Corp., said installers should test the subfloor’s moisture levels prior to installing MLF products like Congoleum’s Triversa.

“Moisture vapor emissions should not exceed five pounds or 1000 s.f. for calcium chloride and 85% rh for In-situ probe,” said Cea. “If test results exceed recommended levels, proper remediation steps should be taken before installing Triversa. For concrete in new construction that has not been allowed to fully cure, it is recommended that four-milliliter clear plastic be used as a barrier.”

Installers should also be knowledgeable of the different types of moisture issues and how to address them, said Altman. “There are two types of potential moisture issues: topical, such as water spillages or leaks on top of the floor, and moisture from underneath, such as high moisture in a concrete slab,” he said. “For topical spillages, such as around showers, toilets, sinks, etc., fill the expansion space using a silicone caulk or sealant to prevent water from getting underneath the floor. Concrete substrates should be tested per ASTM F2170 or ASTM F1869, and follow the manufacturer’s recommendations regarding remediation.”

One of Mohawk Flooring’s multilayer products, SolidTech, was recently put to the waterproof test, as a result of the unfortunate aftermath of Hurricane Harvey in Houston. “A builder of ours had a block of model homes, and in that block was a big cooking school,” Flannigan said. “Well Harvey hits, and there was four feet of water in that building on top of the product.”

The installers were able to go in, unsnap the entire floor, dry it out and reinstall the planks in perfect condition without any problems, said Flannigan. “It did not compromise the locking system and didn’t hurt that floor one bit,” he said. “The installers said it looks like it never happened. I knew [our products] could do that, but I have to say this is the first one I’ve seen done that was literally under four feet of water.”

Ease of Installation

Most MLF products consist of a click and locking system, which makes it easier to install and allows for faster repair service. However, not all locking systems are the same, which is why it’s imperative for installers to know the various rules and techniques associated with MLF installation, Altman pointed out.

“There are several different locking systems on the market today and the application techniques do vary,” said Altman. “Installers need to know the differences between the locking systems, specific tools to use (such as tapping blocks), and how to properly assemble the flooring without causing damage. Follow the manufacturer’s instructions and don’t assume that the technique used on one system will work on another.”

Testing out the product is one key way installers can acquaint themselves with how different locking systems work, Daubler added. “Installers should always test out the material to become familiar with how the locking system engages on both the length and short side,” he said. “If a tapping block is needed, use one—and use it correctly—to avoid damage to the flooring or locking profile. Anyone installing flooring should never force materials to fit together.”

Since MLF is a young category, there’s still plenty left for installers to learn, Kups said. “I think there’s a couple of points to keep in mind with this category; it’s just entering the ‘toddler’ stage of growth and we’re all still learning what it can—and in some cases, cannot—do,” he said. “Remember it’s still a vinyl product, so some of the rules still apply from luxury vinyl when we look at flatness, expansion spacing, and yes, even temperatures. Read the instructions and warranties from each manufacturer you are going to sell and install, and ask questions! Tech reps would rather answer questions before a project than inspect it afterwards.”