Excessive moisture in concrete slabs is a problem that will never entirely go away in the construction industry, but manufacturers are working hard to develop products that keep these issues to a minimum. With fast-track construction projects showing no signs of slowing down and the demanding environments floors are being placed in, conducting moisture testing and installing moisture mitigation systems are becoming more and more important tools for installers and contractors. However, just having these products is not enough if you do not know how to properly use them.

Moisture meters. Tom Laurenzi, Delmhorst Instrument Co. president, said fast-track construction deadlines can make installers choose to perform moisture tests in the interest of saving time rather than following the procedures for proper readings. “Moisture tests are often chosen in the interest of meeting a construction schedule rather than what may be best for the situation. Certainly not all tests are alike or produce the same information. It is often best to contact the floor covering/coating and adhesive manufacturer for guidance.”

The two most common moisture tests performed are ASTM F2170, which measures relative humidity (RH) in a concrete slab with in-situ probes, and ASTM F1869, which measures the moisture vapor emission rate of a concrete subfloor using the calcium chloride test. Of the two, Laurenzi said, “If only one test is performed, we believe it should be F2170 because of its ability to develop a profile of moisture conditions throughout and predict (not guarantee) future performance.”

According to Grete Heimerdinger, Lignomat vice president, one important step to moisture testing is calculating its Equilibrium Moisture Content (EMC). Lignomat provides an EMC chart at www.moistureproblems.info/emc.html. When performing a test, make notes for any moisture readings gathered. “People call me up and say, ‘The floor is cupping.’ My first question is, ‘What was the flooring moisture level before it cupped’? If they don’t know, it usually means they were in a hurry or didn’t perform the test at all.”

She believes the in-situ probe test gives users more information than the calcium chloride test. “The calcium chloride test does not look into the depth of the concrete. It may miss conditions that could later affect the floor.”

Andrew Rynhart, Tramex technical director, said a common misconception is believing a concrete subfloor is dry simply because of its age. “Performing ASTM F2170, combined with ASTM F2659 [which measures subsurface moisture in the upper inch of a concrete slab with a non-destructive moisture meter] is a good way to identify potential problems, even in old concrete slabs.”

He added, “We highly recommend users to carry out ASTM F2659 using an impedance meter. This test enhances the benefits of either in-situ or calcium chloride testing, as it allows the user to determine where and when to carry out these tests, and after the full test has been done it allows the user to determine if there are any anomalies within the slab.”

Wagner Meters’ Jason Spangler, flooring division sales manager, believes in the importance of RH testing. “We have spent considerable time and effort educating the flooring industry on the limitations of calcium chloride testing. Only RH testing has proven science behind the development and technology of the method. They only reason I would suggest ever using both test methods is if the specs call for calcium chloride testing as a mandated requirement.”

He added, “The biggest misconception that I see is when installer or contractors assume that a surface-based test  -- whether that’s dropping a match on the slab, calcium chloride testing or the hood method – is going to give them an accurate picture of the moisture that is still in the slab. Moisture levels in a concrete slab are not uniform top to bottom as long as the slab surface is exposed.”

Moisture mitigation products. Danielle Hunsicker, Ardex Americas manager of national programs and specifications, said installers and contractors should be aware of the pH levels of the slab when choosing a moisture mitigation product. “The pH of a freshly poured slab can soar to 12 or 13 but settle to around 9 after curing. However, after flooring is installed, high moisture emissions can cause pH levels to rise again. Choosing a system that tolerates high pH levels assures the product can withstand fluctuating levels.”

Another important consideration is the permeability (or perm rating) of a system. “In 2013, ASTM offered a bit of clarity for those looking to choose a topical moisture control system and officially published a new standard ASTM F3010. ASTM F3010 - 13, Standard Practice for Two-Component Resin Based Membrane-Forming Moisture Mitigation Systems for Use Under Resilient Floor Coverings, requires that moisture remediation systems have a perm rating of 0.1 or less.”

Other products can also impact a moisture remediation system, she added. “Factors such as the type or thickness of underlayment can ultimately affect the performance of the adhesive installed above. Crack and patch repair similarly can impact the rest of the installation. Look for products that are designed to work within a system.”

Bostik’s Eric Kurtz, hardwood and resilient flooring systems market manager, said his company offers several moisture products. “New types are emerging, such as Bostik’s Axios Tri-Linking Polymer Technology. Bostik has a range of hardwood adhesives that reduce moisture vapor transmission from the slab without using a separate mitigation product.  In some circumstances a separate mitigation product is desired, so Bostik has developed a range of epoxy systems as well as polyurethane membranes.”

He said a common misconception is assuming a slab is dry simply because it looks or feels dry. “If a slab is dry but on grade, changes in moisture in the surrounding soil (e.g., heavy rains or drought) will cause changes in moisture of the slab itself.  Even installation of the flooring itself may cause changes in the moisture content of the slab.”

According to Steve Taylor, Custom Building Products director of architecture and technical marketing, installers and contractors need to understand that only taking one moisture reading does not provide comprehensive data. “Many readings need to be taken to confirm the vapor transmission rate of the slab in question. If high moisture vapor transmission is measured in some areas, it is best to assume there is or will be a problem over the entire area at some time.”

He also highlighted the importance of following manufacturer instructions. “The concrete floor should be properly prepared according to the directions.  In most cases the concrete slab will need to be shot blasted to ICRI CSP 3. Next, it is very important to remove all dust with a vacuum, not just a broom. Most moisture control products are multi-component and it is important to follow the manufacturer’s mixing instructions.”

Taylor added that expansion joints must be properly treated in the concrete slab. “These joints are placed to allow movement in the concrete slab; however, this movement can damage the moisture mitigation membrane if not properly treated. It is important not to just cover over these movement joints with the moisture vapor control system. The joint must be incorporated into the system, by following manufacturer and industry guidelines.”

Larry Scott, DriTac’s vice president of field technical services, agreed that following manufacturer instructions is essential to a trouble-free installation of a moisture mitigation system. “If a specific trowel is required, make certain an installation is not conducted with anything other than that exact trowel.”

He noted that moisture problems can sometimes extend beyond the slab itself. “Moisture can originate from several different entry points in any given installation and adversely affect the floor covering used. Moisture-related weak points surrounding or within the installation, such as from side walls, will not be protected by a moisture control flooring system.”

Scott stated that moisture mitigation products have become more advanced, both in the type of settings they can be used in as well as in the application tools and methods. “However, regardless of the product, technology, and application method utilized, it is important to remember that adherence to proper product installation guidelines, recommendations and requirements should always be at the forefront of any floor covering installation.”

Mark Lamanno, Franklin International technical market manager, flooring, said it is a mistake to assume that all moisture mitigation products behave the same. “There are different methods of application for different products.”

Some basic rules of thumb he follows: “Always be sure the concrete is clean of all debris as well as of any curing compounds or bond breakers that might inhibit bonding. Some subfloors require shot blasting, scarification or simply surface grinding to enable a mechanical bond.”

He added that the industry has come a long away in the type of moisture mitigation products available. “The industry first used vinyl as a moisture barrier. Then we had epoxies. Now, we have a variety of adhesives that can and will mitigate moisture in the subfloor. Two newer Titebond products are Titebond 531-Plus Moisture Control System and Titebond 771-Step Adhesive, for moisture and sound control.”

Ron Loffredo, H.B. Fuller Construction Products senior area technical manager, said while installers have become better educated about using moisture mitigation systems, “in general installers and contractors need to know that each moisture control product is different and has its own nuances, so it is very important to follow the manufacturer’s guidelines.”

He said it is also vital to prepare the substrate properly before applying any type of moisture vapor barrier. “This includes addressing dynamic and static cracks in the concrete, as per the product’s instructions. Anything larger than the width of a debit card should be filled, as it could allow moisture to pass through, potentially causing the moisture mitigation system to fail. The substrate should also be cleaned of any contaminants before applying the moisture mitigation system.”

According to Howard Kanare, Koster American Corp. technical director, the most effective products are 100 percent solids and are engineered to form a continuous membrane on the surface of the concrete. “Products containing water or organic solvents do not block moisture as well as ‘100% solids’ coatings. ‘Deeply penetrating’ into concrete dilutes the effectiveness of the products – the lowest water vapor perm ratings are achieved with resins that cure highly cross-linked and form a well-bonded, continuous membrane on the surface of the concrete.”

He said applicators and installers should pay special attention to achieving the specified surface profile and applying the coating at recommended coverage rates. “A concrete surface that is too rough or a coating that is too thin will not adequately block moisture from within the concrete.”

As for new developments in moisture mitigation, he said companies are developing products with extremely low or no VOCs. “These are suitable for use in sensitive occupied building environments such as hospitals, clinics, schools and daycare facilities. Some products are formulated to cure quickly so the facilities can be put back into operation with minimal disruption.”

Yoni Feldman, Laticrete product manager, noted the following common misconceptions about moisture mitigation products: “That they are also a waterproofing and/or crack suppression membrane; that the concrete slabs receiving moisture mitigation do not require preparation; and that ASTM F1869 and ASTM 2170 correlate to one another.”

According to Feldman, none of those assumptions are correct. Regarding subfloor prep, “concrete slabs must be clean, structurally sound, absorptive, and have an ICRI concrete surface profile of 3 to 5. All dirt, oil, paint, laitance, efflorescence, sealers, curing compounds and any other bond breaking contaminants must be removed down to the full depth of contamination by shot blasting or other mechanical means, then swept and vacuumed clean. Surface temperature must be 50-90°F (10-32°C) during application and for 24 hours after installation.”

MAPEI’s Jeff Johnson, Floor Covering Installation Systems product manager, said a common misconception is believing epoxy moisture barriers will provide moisture protection “even if you exceed the stated coverage limits provided by the manufacturer. The truth of the matter is that in order to get proper functionality the installer needs to make sure the thickness of the membrane being applied meets the requirement of the manufacturer.”

Subfloor preparation is also a key component to a successful installation. “If you are applying anything that will be bonded to the subfloor, the subfloor needs to be clean and free from anything that could release or dissolve with moisture vapor exposure. For epoxy moisture barriers that means the subfloor typically needs to be shot-blasted. Not all manufacturers of epoxy membranes require shot-blasting but all will agree that doing so will enhance the bond of the epoxy to the subfloor.”

He added that one of the latest developments in moisture control is additives placed directly in the concrete, but these are not failsafe. “If moisture is not allowed to move through the concrete then the RH levels are always going to be extremely high. The other issue is these concrete slabs become virtually non-porous, so using installation methods that use adhesives requiring a porous substrate are going to be a problem. Our industry needs to look further into these additives and decide how to approach them in terms of moisture emission testing.”

Brian Petit, NAC Products vice president of operations, said when looking at moisture mitigation products, it makes sense to choose products that work together in a system. For his company, that means “using NAC’s Moisture Lock 101, a chemical-based floor hardener that soaks into the pores and capillaries of the concrete and seals it. Up to three coats can be applied. NAC primer would then be applied, followed by full floor coverage of the membrane.” Petit added, “Patience is also important. If using the Moisture Lock 101 product, it can dry in a few hours, but for best results allow for a full 24 hours of drying.”

Ed Farrington, technical operations manager for nora systems, said there are many options for moisture mitigation systems on the market. “The types of moisture mitigation systems out there are film-forming resins, penetrating, and non-film forming and resurfacing overlays that specify the use of a primer before applying the cement-based moisture control material. Our company recommends products that meet ASTM 3010-13, such as nora membrane [as part of the nora pro install system designed specifically for nora commercial floors].”

Whatever an installer or contractor uses, “it is recommend you consult with the manufacturer for your specific application. Products are not all the same and have varying moisture limits and installation criteria.” He added that with fast-track construction becoming more commonplace, “everyone is looking for that magic potion that is a solution to high-moisture concrete in cases where moisture-sensitive floor coverings are installed.”

According to Tom Cassutt, ProSpec product manager and R&D director, when installing a moisture mitigation product, “do a job mockup, minimum of 100 sq. ft., and test the tensile bond strength after 24 hours. To perform properly, the concrete surface must be porous enough to achieve full penetration of a moisture mitigation system.”

He added, “The concrete must have a direct tensile bond strength of greater than 200 psi. Honor all expansion joints and repair non-moving cracks. Mix all components thoroughly, being sure to incorporate all unmixed material. Apply at the recommend thickness; after it has cured, check for and repair any pinholes or imperfections in the coating.”

Tracy Muller, QEP adhesives product manager, said recent advancements in moisture mitigation products include moisture-block adhesives, which “serve as a one-step moisture control method. High readings would generally require an epoxy-based system. In instances where levels are below 95% RH, moisture mitigation adhesives may be used.”

She stated that the new Roberts Moisture Control Adhesives “now withstand up to 10 pounds of moisture vapor emissions rates or 90% RH in a single step, simplifying the moisture mitigation process.”

Hubert Steinberg, Schonox manager, export and industry, said along with epoxy-based systems, urethane and acrylics are available as well. “You can’t just say, ‘This one type is generally limited or not, but all of these types have their limits depending on the chemistry they are based on. While nowadays epoxy is the most common technology in moisture mitigation, this may/will change in the future,” he predicted.

Steinberg added, “Basically, all of these systems are pretty easy to apply following the [manufacturer’s instructions] and accepting the mentioned limits. The main issue is the subfloor prep prior to installing the moisture mitigation systems (making sure there is no hydrostatic pressure, achieving the surface profile, etc.)”

Regarding W.F. Taylor’s products, Gary Liddington, business manager, noted, “One-hundred percent solids modified silane moisture mitigation/installation systems such as W.F. Taylor’s MS Plus products for wood and resilient flooring are a one-step, one-application system that provide moisture mitigation, sound deadening and crack isolation properties as well as providing for excellent installation of the flooring products.”

He said it is important to understand what different moisture mitigation systems can and cannot do. “There are a lot of products that are nothing more than floor primers. These do not actually mitigate moisture; they merely make the surface better to bond to.”

Liddington added that the most important step of any moisture mitigation application is reading the instructions carefully. “These instructions generally will address moisture measurements of the subfloor, subfloor preparation, minimally acceptable jobsite conditions, and instructions for application of the moisture mitigation product. Failure to follow allof these instructions exactlywill most probably result in less-than-desired results.”


NOTE: For more photos of products and their application, visit the Digital Edition of this issue. Find out more at www.fcimag.com/digitaleditions.