It is a very common mistake people make when it comes to mositure protection, people often think that mositure mitigation systems and moisture tolerant adhesives have the same job. Repeatedly moisture related floor covering systems continue to fail at an unacceptable rate. Moisture issues are not just limited to slab on-ground construction but can also occur when floor coverings are installed over suspended concrete slabs as well. When moisture issues occur, it is serious and will affect all parties and can become very costly. Modern test methods were invented to prevent distress and failure by testing the concrete’s dryness before any floor coverings or coatings installed over the substrate. Concrete in-situ relative humidity testing has become the most popular method to use in the United States and is the most accurate when it comes to testing the concretes dryness. It also is the most overlooked part of construction; people don’t want to spend the money or just don’t have the knowledge and history of testing concrete slabs.
Relative moisture testing is not just used for new concrete floors, it is used every day for old concrete slabs as well. The earliest reports of moisture testing dates all the back to 1954 when studies were done on the emission, moisture transmission and concrete drying. According to “Housing Research paper 28” that was commissioned by the U.S. Housing and Home Finance Agency, “Changes and new developments in building construction during the past few decades have brought about an increasing need for control of moisture which often migrates upward from the ground”. This section describes the effects of vapor pressure associated with temperature and humidity levels above, internal, and beneath a concrete floor slab. This is where moisture mitigation systems and moisture tolerant adhesives come into play when protecting your concrete slabs. Moisture Mitigation systems are moisture barriers, moisture barriers control moisture in a vapor state. These systems fill the pores of the substrates, typically with some sort of epoxy or polymer. They stop the moisture vapors from passing through the substrates, these products are well-suited for treating all high-moisture slabs, new or old and stops it from happening in the future. Moisture mitigation systems stops the movement of water vapor from the exterior sources, like groundwater, or moisture vapor from a subfloor system itself, like from an insufficiently dry concrete slab.
In 1954 a study was made to prove the value of a sub-slab vapor retarder and it concluded that concrete floor slabs could be created that would pass less than 3 pounds of moisture per 1,000 square feet per day. “Provide a membrane consisting of one layer of 55-pound roll roofing or one of the equally effective and durable new membrane materials, lapped 6 inches, turned up and extending to the top of the slab around all edges, with all laps carefully sealed with hot or solvent-type waterproofing asphalt.” This has proven to us that felt products are not suitable for long term exposure of moisture, therefore it is so important to use a moisture tolerant adhesive under any product about to be installed over a concrete slab. By not using a moisture tolerant adhesive under carpet or resilient flooring, this could result in your floor coverings failing and/or molding.
Flooring adhesive manufacturers have been chasing the moisture-resistance levels that were possible with black cut-back adhesives for around 35 years, this was a solvent-based adhesive, that was later discovered to produce asbestos. Although it was found to contain asbestos, this was a very durable and water-resistant adhesive, but the dangers of asbestos were also discovered which resulted in lawsuits emerging. As manufacturers started moving away from solvent-based adhesives all together, because of the high levels of dangerous volatile organic compounds(VOCs). High levels will negatively impact a building’s indoor air quality and its occupants’ health. They then started using a water-based adhesive, water-based adhesives cannot stand moisture as much as the solvent-based adhesives, but in the end, safety is what matters most. Nowadays they’re coming out with new technology that is water-based and are meeting the level of moisture resistance that is comparable to the old solvent-based adhesives. Inclusion, moisture resistant adhesives are never going to be 100% moisture resistant, we will always recommend a moisture mitigation system on the slab as well, just to ensure the safety and lifeline of your floors.
Call HTC Commercial Flooring for any moisture related issue, we have got you covered. (708)942-5800. All facts were referenced from “White Paper” Concrete In-situ Relative Humidity Testing – Friend or Foe? By George Donnelly