By Rich Hartman, Fishman Flooring Solutions
“In life,” it has been said, “change is inevitable. In business, change is vital.” That certainly describes the flooring installation industry today.
A case in point regarding the changing flooring installation landscape is the new adhesive technologies that have been brought to the marketplace recently. These highly-tested adhesives, which have replaced the solvent-based adhesives that were prevalent in the past, contain few or no volatile organic compounds and there is virtually no off-gassing from them.
Newer Adhesives Bring Many Benefits
While the sustainability aspects of these new technologies are important, they bring many other benefits to the marketplace as well. For one, they are more efficient, meaning less adhesive is necessary for a successful flooring installation than when their predecessor adhesives were in use. They also have longer open times of four to 24 hours, which enables the installation of luxury vinyl tile (LVT), and other types of flooring, over much larger spaces.
In lockstep with these new adhesive product introductions has been the emergence of LVT as the flooring product of choice not only in the residential sector, but also in the commercial segments from healthcare to retail to education.
Given the significant amount of LVT currently being installed and the influx of new adhesives into the marketplace, it’s critical that flooring installation contractors make informed decisions about both the LVT and the adhesives they use on a specific job and understand how to use them properly. Here are some things to consider with respect to adhesives and LVT installations.
LVT Dimensional Stability
Many of the lower priced LVT products on the market are made with recycled content. It is important to ensure that these products meet ASTM International (ASTM) standards for dimensional stability, because even a high-quality adhesive will be challenged when used to install an LVT product sold at the lowest price points.
Clean and Smooth Substrates Are Critical
Many of the newer roll-on or spray adhesives require clean and smooth substrates. This enables a 100% bond between the LVT, the adhesive and the substrate. When the LVT is to be installed over an existing vinyl floor that is non-cushioned, the floor must be free of waxes and other foreign substances that would affect the efficacy of the adhesive. Dust and dirt should be removed from wood or concrete substrates by sweeping, vacuuming or mopping.
New Generation Pressure Sensitive Adhesives
Pressure Sensitive Adhesives (PSAs) for LVT installations are new to the marketplace. As such, flooring installation contractors must understand how and when to use them. PSAs for LVT can be used wet set or as a PSA adhesive. The LVT manufacturer’s installation instructions will indicate which method to use.
Many adhesive manufacturers have increased the recommended relative humidity (Rh) level of their PSA adhesives to 95% or 99% when installing LVT over concrete. However, these adhesives do not remediate moisture, which can lead to problems. Your local flooring supplies distributor can recommend a moisture test that can ease concerns about moisture.
Transitional PSA adhesives are frequently used on both porous and non-porous substrates. It is important to understand the porosity of the substrate when using transitional adhesives, because the more porous the floor, the more adhesive will be needed. Transitional adhesives can be used either wet or dry. Many LVT manufacturers will recommend their preferred method, depending on the product and type of installation.
The traditional method of installing LVT with transitional adhesives is to spread the adhesive and let it dry to the touch. Some transitional adhesives remain in a tacky state for up to 24 hours during which LVT can be installed, which works well on very large installations. When using the wet set method, the adhesive should only be spread over an area where the LVT can be easily installed before the adhesive tacks over.
Adhesive Compatibility with the Substrate
Among the most important considerations when using newer adhesives is to understand the characteristics of the substrate and select the adhesive accordingly.
With concrete, moisture in the slab is a critical consideration, because if Rh levels exceed the manufacturer’s limitations, the LVT installation may fail. Today, most adhesive manufacturers require stringent pre-installation moisture testing, not only on the surface, but also 40% into the depth of the slab. For example, for a 6″ slab, the moisture testing probes should be set at a depth of 2.5″.
When plywood is used for underlayment, it must be associated grade meant for floor covering. This ensures the plywood was glued with waterproof adhesives, so moisture from the flooring adhesive will not affect it. This grade of plywood is also sanded smooth.
Many adhesive manufacturers do not recommend installing LVT over OSB because the resins used to make OSB can’t be identified to determine their compatibility with the adhesive. Also, some OSB is now waterproof and may contain surface wax. As a result, it is best to install underlayment over OSB. This will also ensure a smooth surface on which to install the LVT.
If the LVT is going to be installed over gypsum, sealing is required so the adhesive will not be absorbed into it. Applying one or two coats of acrylic sealer will be sufficient.
The Stakes are High
Correctly selecting and using the right adhesive when installing LVT is critical. Doing so will ensure the LVT rests on a solid foundation. Conversely, ill-informed decisions can lead to costly remediation, dissatisfied end users and a black eye for the flooring installation contractor, as well as for the flooring industry.
About the Author: Rich Hartman, territory business manager at Fishman Flooring Solutions, has witnessed the evolution of both LVT and the adhesives used to install it during his more than 30 years in the industry. He can be reached at Richard.Hartman@lfishman.com.