Flooring adhesive manufacturers have been chasing the moisture resistance levels that were possible with black cut-back adhesives for north of 35 years. This was a solvent-based adhesive, asbestos-containing adhesive, which was extremely durable and water-resistant. 

Of course, as the dangers of asbestos were discovered — and lawsuits emerged — black cut-back adhesives were quickly phased out of production. Then, adhesive manufacturers started moving away from solvent-based adhesives altogether, as they can emit dangerous levels of volatile organic compounds (VOCs). High VOC levels can negatively impact a building’s indoor air quality and its occupants’ health.

Safer, water-based adhesives took their place. But the old solvent-based technology was proven to withstand moisture and stand the test of time, while the new, water-based technology was still in its infancy.

Fast forward to today. We now have water-based adhesive technologies coming out that are meeting the level of moisture resistance, adhesion and quality comparable to the old black cut-back adhesives.

The North American flooring adhesive market is expected to grow to $1.1 billion within the next five years, according to Stratview Research. Much of this growth can be attributed to the boom of effective low VOC, water-based products, which are now flooding the market.

The rise of safe and highly moisture-resistant flooring adhesive technology

Within the last five or 10 years, adhesive manufacturers have unveiled products which allow you to install flooring in higher relative humidity (RH) conditions — as high as 90, 95 and even 99% RH. RH is a measure of the moisture present in a concrete substrate.

Every manufacturer seems to be coming out with their own line of adhesives they claim is bigger, better and stronger. To give you an idea of the level of innovation on the market today, here are a couple product highlights:

  • Interface’s TacTiles for tile flooring- Designed for modular flooring, like tile, TacTiles from Interface are easy to install, low in VOCs and highly resistant to moisture from the substrate.
  • MAPEI’s high-moisture adhesive options- MAPEI, a leading adhesive manufacturer, separates their line of moisture-resistant adhesives by moisture level. They give product options for slabs with 90% RH, 95% RH or even 100% RH, depending on what the results of your moisture test are.
  • Shaw’s LokDots for carpet tiles- Shaw’s innovative LokDots carpet tile adhesive permits installation in conditions up to 100% RH, if no visible moisture is present. Emitting near-zero VOC levels, it can even contribute points for a LEED v4 certification for your building.

How to select a moisture-resistant adhesives in today’s market

Despite the saturation of the market, choosing your adhesive is relatively easy; the process is much the same, regardless of which material you choose.

First, you choose your flooring material based on application, aesthetics and long-term value. From there, you should follow the manufacturer’s recommendations. The manufacturer has done their testing and due diligence, and knows which adhesives and moisture levels will work for their product and which won’t.

By and large, we tend to use the adhesives recommended by the manufacturer of the flooring system you choose. Following the manufacturer’s specifications will also ensure your flooring installation will be covered by the warranty.

Despite higher moisture resistance, moisture mitigation remains vital 

Flooring systems, including adhesives, are designed to be installed at certain moisture levels and no higher. If your slab exceeds this threshold, your adhesive will release and your flooring will fail — no matter what type of flooring you choose or how moisture-resistant your adhesive is.

This is a huge deal since moisture-related failure of flooring installations accounts for 90% of commercial flooring litigation. And yet, a meager 1.5% of budgets are put toward moisture management, according to a Resilient Floor Covering Institute article.

The cost of moisture failure is just too high to leave it to chance. This is why your flooring contractor tests your substrate for moisture prior to installation. Moisture-related failure of your flooring system is almost always preventable through moisture testing and the installation of a mitigation product.

Your contractor will test the slab in controlled conditions to determine if the RH in your slab exceeds manufacturer’s recommendations. For example, a flooring product and its adhesive might be certified for installation up to 90% RH. If your slab tests at 95% RH, you’ll need to install a moisture mitigation product over the slab, usually a roll-on or full-spread vapor barrier product.

For lower cost applications, sometimes a premium adhesive will work — if it exceeds the manufacturer’s specifications for moisture. However, in some high-stakes, high-cost applications, you should consider installing a mitigation product even if the RH level doesn’t exceed manufacturer specifications.

For example, we once completed a unitary flooring installation for a clean room where they filled prescriptions for radioactive materials used in heart cauterizations. We ran the moisture tests and the RH was well within recommended levels. We still recommended moisture mitigation as a precaution because, for this application, the cost of replacement would be so steep if a moisture problem were to pop up in the future. To save money, they opted not to do so. Now, there are bubbles in the flooring, indicating moisture is trapped below the surface. In applications like this one, the cost of moisture mitigation pales in comparison to the cost of replacement.

The bottom line is this: you can’t afford not to do moisture mitigation if you need it. The benefits of the latest adhesive technologies are wide and far-reaching, from better indoor air quality to less risk of moisture-related flooring failure. But, even though they’re better at resisting high levels of moisture, they do not serve as a substitute for moisture mitigation.