With the popularity of LVT still high, resilient flooring shows no signs of slowing down. More customers looking to have resilient installed in both residential and commercial settings have brought new advances to the segment as manufacturers look to create products for every type of resilient floor, and for every type of setting. Question is, what types of products should contractors and installers choose?
Jeff Johnson, MAPEI’s Floor Covering Installation Systems product manager, has a basic rule of thumb for selecting a resilient flooring adhesive. He said that standard acrylic adhesives will work in most situations that see light to moderate traffic. “For higher traffic there are specialized acrylics plus two-component systems available. For the highest traffic resistance, epoxy adhesives would be the best choice,” Johnson added.
Johnson is seeing several technological advances in the resilient adhesives category, including “water-based adhesives with higher moisture resistance that can be used in fast-track installations, factory-applied tape systems, fast-setting two-component epoxy systems and hybrid polymer moisture-cure adhesives.”
In commercial settings, he is also starting to see moisture mitigation being completed before the floor is even laid down. “This means an epoxy moisture barrier is installed first (even if there was no moisture problem evident) and then a self-leveling underlayment is applied. True, it is an added upfront cost for the contractor but the risk of expensive tear-out and downtime for the location oftentimes outweigh the initial expense.”
Johnson also shared a best practice when working with a two-component reactive adhesive: “Always make sure to use ‘walk-off’ boards on recently installed flooring. This will help make sure that the wet adhesive below the flooring does not get pushed out under a footprint or the weight from the 100 lb. roller. If this happens, you could see the footprint, roller mark or even a bubble in the finished product.”
Jim Gourley, owner of Bone Dry Products Inc., said manufacturers are enhancing their products to withstand higher-moisture environments typical of fast-track construction. “Some products are now recommended up to 12 lbs. and 95% humidity, and up to 10.5 on the pH scale. This upward tend should continue. Products are also available for sealing and moisture mitigation on slabs as new as 14 days.”
When working with a concrete substrate, pH levels always need to be considered. “A high pH surface with excess moisture can damage and break down floor coverings and adhesives,” Gourley said. “The pH level of new concrete will be approximately 12 to 13. As the concrete surface reacts with carbon dioxide in the air the pH is gradually reduced to approximately 8.5.”
He added that while it is good to see so many technological advances in resilient adhesives, contractors and installers should still take product claims with a grain of salt. “While numerous adhesives are needed for the different types of flooring to be installed, the adhesive industry is getting a bit carried away sometimes,” Gourley commented. “It’s sort of like bringing blue and brown eggs to the market and charging more for them because they’re better for you. An egg is an egg regardless of the color.”
According to Ralph Richins, Q.E.P. Co. Inc. regional sales manager, resilient flooring adhesives manufacturers have also had to adapt their products to the wide range of resilient floor backings available. “In addition to felt back, we now have vinyl-backed, fiberglass-backed, limestone-backed, urethane-backed and rubber,” he said.
Compounding the confusion for installers and contractors, multiple types of adhesives are offered for different installation settings. “There are thin spreads, latex-based, urethane-based, acrylic-based and epoxy. Then there are two types of pressure-sensitive adhesives: Conventional, which remains a soft set and is a releasable product; and hard set, which after two hours begins to harden and is totally cured in six to eight hours. It is not releasable,” Richins noted.
How to choose which adhesive for which situation? Richins recommends checking with the flooring manufacturer and using whatever adhesive and application method (spray, trowel, roll on) they say is best for the product.
Richins also said to follow certain steps when prepping the substrate. When dealing with a concrete substrate, use a Portland-based patch when patching or floating imperfections in a concrete floor. When installing over gypsum concrete, prime the floor with a latex primer.
When installing over a wood subfloor, nail or screw the floor down as necessary to ensure there is no looseness. “Make sure all knots are tight. If they are not, dig them out and patch as necessary. Make sure all nail heads are countersunk and patched,” he noted.
Additionally, any stains on a wood subfloor that could bleed through should be primed with a stain blocker that is compatible with the adhesive used. Richins continued, “If the subfloor is marginal, it is always best to use underlayment. Make sure the joints are staggered and if using 4’x8” sheets that they are running perpendicular to the existing subfloor and overlap existing joints by at least 12 inches. Underlayment should be stapled down every four inches. Patch and smooth joints as necessary.”
Finally, when installing over a non-porous floor such as terrazzo, granite or ceramic, rough up the floor first. “These adhesives have what we call a mechanical bond, so they must be able to adhere to the substrate. This is done by opening up the pores of the floor,” Richins explained.
Marc Sims, Franklin International director of sales, construction division, stressed that it is essential to always follow the flooring and adhesives manufacturers’ instructions to the letter.
“Being as skilled and talented and experienced as you are certainly goes a long way, but for most of us manufacturers, the instructions are close but they’re not all the same,” he said. “Even if you’re using the same type of product you’re used to but a different brand, read those instructions, follow those instructions, and read the warranty; make sure you’re covered.”
When in doubt, call the adhesive manufacturer’s technical service line. “It’s always better to call before; not after,” he added.
More on subfloor prep. According to John Lio, DriTac marketing manager, when prepping the subfloor to accept a resilient adhesive, make sure the subfloor is clean, flat and dry. “Prepare the substrate by removing existing floor coverings, adhesives, patch residue, dirt, paint, grease, oil, sealers, waxes, curing compounds or other contaminants,” Lio said.
“For flatness, industry standards are 3/16” in 10 feet and 1/8” in 6 feet. Finally, if the subfloor is damp or shows visible signs of moisture, it should be allowed to dry before the flooring installation,” he added.
Chris Eichman, Bostik Inc. marketing communications manager, said there should be no voids or projections in the subfloor. “There are many factors when selecting an adhesive: substrate, environment, floor covering material, usage, expected life, cost, warranty, local codes, etc.,” he noted.
According to Sonny Callaham, Royal Adhesives & Sealants technical product manager, another important step when prepping is to give the flooring and adhesive time to acclimate prior to installation. “Temperature variations just before and just after installation can cause the flooring to expand or contract no matter what type of adhesive is used. Flooring adhesives are not designed to prevent the movement of floor covering after installation,” he explained.
Callaham added that it’s important to work with the customer to work out the details beforehand, including where the floor is going, what type of traffic it will face and how long the end-user expects to have the flooring in place. “This all needs to be done on the front end of the bid (or sale) and be ready for the installer once installation is scheduled. Contract houses who provide the underlayment and adhesives to their installers tend to have a higher success rate,” Callaham noted. Gary Liddington, W.F. Taylor business manager, offered his take on the best conditions in which to acclimate a job site: “The adhesive, floor covering, and area to receive flooring must be maintained at a temperature of 65° to 95° F (18.30° to 35.02° C) and at a relative humidity of 30% to 60% for 72 hours before, during, and after installation.”
He also noted that contractors and installers should always follow instructions. “Due to the non-porous nature and flexible properties of most resilient floor coverings, resilient flooring installation can be quite unforgiving of poor installation technique,” Liddington said.