Adhesives serve many purposes in floor covering installation, with the main purpose being to hold your flooring in place. They may also be formulated to have additional features to protect your job. One such feature is flexibility, as with urethane adhesives and hardwood flooring which allow the wood to expand and contract or soft setting re-tackable carpet adhesives. Others such as ceramic adhesives are formulated to be water resistant, especially when used in high water areas such as showers. That is why there are two types of ceramic adhesives, Type I and Type II. Type I may be used for walls and ceilings in light construction with wet requirements. Type II may be used on walls and ceilings, light construction, dry or limited water exposure.

Big thanks to JJ Haines for the info.

Below is a partial glossary to help explain some of the terms we use both before and after an installation problem.

We have all heard of plasticizer migration, a term used when plasticizers leave a flooring product and enter an adhesive, turning it into a soft, gooey mess with no holding power. An example of this would be using a multi-purpose adhesive with a vinyl-backed sheet floor. The plasticizers in the vinyl-backed sheet floor leech into the multi-purpose adhesive, breaking it down leaving a mess. A plasticizer is a product that is used to soften and provide flexibility in various flooring products such as vinyl sheet goods and vinyl backed carpet tile. Two examples of plasticizers are mineral oil and hydrocarbon oil. Plasticizers are also used in adhesive compositions since it improves tack, and develops “legs.”

The word polymer is used extensively. A polymer is a compound used in the adhesive’s components. It can be natural rubber, styrene butadiene rubber (SBR) or neoprene.

Binder is another term not fully understood. A binder is the substance that holds the adhesive itself together. The adhesive actually gets its common name from the binder. Some common binders are rubber-resin, latex-resin and asphaltic cut back.

Resins are solid or semi-solid maternal. They are either natural or synthetic. Usually insoluble in water, their purpose is to improve adhesion, improve tack, “wetting” of substrate, and improve the film strength by stiffening the film. Some common resins are vinyl, acrylic, gum rosin, wood rosin and hydrocarbons.

Fillers are basically substances of a non adhesive property. Fillers are added to lower the cost and also improve characteristics. Fillers control viscosity and stiffen the film. Some fillers are clay, silica, carbon black and calcium carbonate.

Of course none of the adhesives would be worth much without additions such as thickeners, antioxidants, light, and heat stabilizers, and without preservative (to prevent bugs), surfactants for wetting and stability, and emulsifiers.

Now that you know how an adhesive is made, we can talk about some of the problems we see in the field:

Balling-up: This condition results when adhesive cannot be troweled properly. Since wetting agents and other goodies are usually present in the formula, the most common reason for balling-up is a dusty substrate, or when an adhesive, from age, is losing stability.

Adhesive failure: This is an occurrence where the adhesive fails to bond to the substrate or the back of the flooring product. If the failure is in the substrate, look for dampness, curing compound or a weak and dusty surface. If the failure is the flooring itself, it most likely means poor adhesive transfer due to a bad or wrong size trowel, or waiting too long to place your flooring, causing the adhesive to be skimmed over, preventing transfer. Also, an incorrect adhesive may have been used.

Cohesive failure: This is failure within the adhesive itself. This condition is identified by seeing a separation, with adhesive bonding to the substrate and the back of the flooring. This can be caused by use of an improper trowel size, installing too soon into wet adhesive that hasn’t begun to firm up, or premature movement of the flooring product itself or even defective adhesive.

Freeze-Thaw Stability: This problem is not all that it seems to be. For example, one adhesive may be protected to 10 degrees with 3 thaw free cycles. Another may be protected to 0 degrees with a different number of cycles. Sometimes the length of time in hours can affect the reliability of the adhesive, so protect your adhesive.

No longer are consumers limited to carpet, sheet goods and tile – they can now enjoy the resurgence of homogenous vinyl, along with unique looks created from cork, bamboo, exotic wood and luxury vinyl tile. Contractors and installers looking to maximize profit while minimizing the risk of callbacks need to stay ahead of the curve when it comes to new floor covering products, to ensure they choose adhesives that perform effectively.

Carpet
When choosing an adhesive for a carpet installation, one must consider the type of backing, necessary grab, traffic load, maintenance schedule, and quality and lifecycle of the carpet. Historically, the two most popular carpet backings have been ActionBac and jute. However, industry demand for fast-track carpet installations as well as new technologies and materials have led to a new world of carpet backings, including: smooth, rough and woven unitary, hot-melt, Kanga, Karastan and solid PVC. Moving from two-step to one-step added carpet installation methods, such as with Enhancer-backed carpet, meant that adhesives also had to evolve to provide more aggressive bonding. The majority of today’s one-step carpet installations rely on the use of styrene butadiene rubber (SBR)-based adhesives due to their fast grab and excellent re-tacking characteristics. For builders and business owners desiring a short-term carpet installation, an economy-grade, SBR-based adhesive would be suitable.

On the other hand, a higher-end, commercial installation expected to last several years, which calls for double glue-down application, would require a higher-grade adhesive. For carpets without design patterns where seams can be “trace-cut,” an adhesive offering ultra quick grab should be used. This will allow the carpet to be rolled right away, ideal for today’s fast-turnaround installation schedule. More expensive, patterned carpets require a higher-quality adhesive with strong grab and appropriate slip time for matching up the patterns.

Sheet-goods adhesives
It is imperative that the sheet-goods backing (e.g., felt-backed vinyl, PVC-backed vinyl and solid PVC) dictate the choice of adhesive for the installation, thus avoiding the dreaded “plasticizer migration” syndrome and subsequent callback. When an incompatible adhesive is used to install solid vinyl sheet-goods products, the chances are high for experiencing bubbling, severe discoloration and installation failure. Avoid product incompatibility by checking the flooring manufacturer’s recommendation for proper choice of adhesive.

Be sure to consider the specific application criteria that the sheet-goods installation will be subjected to. For example, if the floor-covering product will be subject to heavy “point loads,” as in healthcare facilities, a harder-setting adhesive such as an epoxy adhesive should be used. The reason for this is that the epoxy adhesive sets up hard and will not indent like most one-part latex based adhesives. While a higher-quality, more durable adhesive may cost a little more, the chances of installation failure now and later drop significantly.

Vinyl composition tile
While adhesive selection for a typical vinyl composition tile (VCT) installation should be foolproof, experienced installers could tell you otherwise. Quite often, a VCT installation appears flawless on the day of installation but has tiles mysteriously out of position on the following day. Chances are, another construction trade trampled across the floor, moving ladders or carts and causing “fresh” VCT to slide. Having to execute immediate damage control creates much grief for both the floor-covering installer and contractor. Spending a little more money on an adhesive with a shorter open time, very aggressive grab, ultra high shear strength, and the proper trowel notching is critical, particularly in fast-track, heavy commercial flooring applications.

Luxury Vinyl Tile
This product category falls in under the vinyl-backed adhesive category and requires higher end vinyl adhesives. Using a VCT Adhesive or a Multi-Purpose Adhesive with these types of products will lead to plasticizer migration failures.

Hardwood adhesives
Wood floor coverings continue to thrive and are growing in popularity. Because wood is a natural product, much consideration must be given to the type of adhesive used in its installation. The type of adhesive appropriate for engineered wood product installations is very different from that for solid wood planks. As is the case for all floor-covering products, wood products need to acclimate according to manufacturer’s recommendations. Because solid wood products require a strong bond, urethane-based adhesives are excellent choices for holding solid wood in place. Once cured, both of these high-quality, solvent-free adhesives provide the needed flexibility and superior bond strength that solid wood installations demand. For approved pre-finished, engineered wood, cork and parquet floor-coverings, a water-based adhesive is a choice pick due to its ultra high tack and excellent re-bonding characteristics. Before beginning any wood product installation, always consult the wood manufacturer to determine if their product is recommended for glue down, because some engineered woods must be installed as floating or nail-down systems.

Keep in mind that in the world of construction, warranties are given with only one condition: The manufacturer’s installation recommendations must be followed. Before beginning any installation, take the extra step of consulting with the floor-covering and adhesive manufacturers regarding the proper adhesives and trowels. Doing so will help protect you from future liabilities and teach you more about the products’ characteristics and capabilities, which pays off with an easier, faster and more successful installation.