Around 12 or 13 years ago is when Bone Dry Products’ installers started to notice flooring moisture issues, said Jim Gourley, president of Bone Dry Products. “We also manufacture wood flooring for retail store chains and that’s the time we started to see elevated levels [of moisture].”
Craig Morris, Ardex Americas technical service manager, said in the past two decades moisture-related flooring failures have “skyrocketed. While many theories exist regarding why we have seen such an increase, most experts agree that central to most failures are due to the rise of the fast-track construction schedule.” Because of project schedules being compressed, the time between breaking ground and opening the door has been minimized, many times to the point that the concrete substrate is not given adequate time to dry.
Graham Capobianco, OEM business development, technical sales at Loba-Wakol, added, “Unfortunately, concrete usually takes a long time to dry—at least 90 to 120 days, per ASTM F710. This is not normally conducive to an aggressive construction schedule that requires project completion in 60 to 90 days.” Those factors have led to the growth and proliferation of moisture mitigation products in the flooring and construction industries.
Gary Scheidker, regional sales manager at W.F. Taylor, pointed out consumer tastes have changed, with hard-surface flooring becoming more common both residentially and commercially. This has led to the need for more moisture-control products. “Permeable floor covering, such as broadloom carpet, allows moisture to escape while hardwood floors, luxury vinyl tile and plank, and sheet vinyl will trap the moisture.”
The nature of flooring projects has also changed. “More floors are being installed over freshly laid concrete or concrete patches in remodeling,” noted Steve Taylor, director of technical architectural marketing, Custom Building Products. “The challenge is that both floor coverings and the adhesives used to install them are sensitive to the moisture.” The use of exotic floor coverings that are highly moisture sensitive can exacerbate the issue, he added.
Environmental and regulatory factors have been also playing a part in how moisture can be handled. Scheidker stated. Environmental legislation has led to the removal of solvents from adhesives and asbestos from flooring. “These products [could] cause health issues, but were extremely moisture-tolerant.”
In order to meet EPA requirements on low-emitting adhesives, manufacturers have had to formulate their products with more water-based technologies, said Mike Glennon, national sales director at Halex/VersaShield, It was previously thought that solvent-based adhesives acted as moisture blockers.
Bill Harrill, vice president of A.C. Tech, echoed these sentiments, stating moisture issues are based more on legislative mandates like California Air Resources Board (CARB) laws than fast-track schedules. “Materials and chemicals, which formerly worked in this environment, have been legislated out of existence for various reasons including toxicity or environmental concerns.”
Capobianco mentioned the 1980s was when he saw concrete moisture first became a serious issue, as permeable vinyl asbestos tile (VAT) and cutback adhesives were phased out in favor of safer water-based adhesives and asbestos-free flooring products.
He also said high pH levels can lead to flooring failures. “Though moisture is commonly seen as the cause of most adhesive failures, it is usually the high pH that moisture carries that leads to adhesive breakdown and bond failure. Moisture issues are prevalent on new concrete slabs, but they can occur on old concrete as well, especially where cutback adhesives and/or permeable floor coverings are removed.”
Harrill explained that to meet CARB laws, the first reformulations of adhesives left much to be desired. “These early products had a high water content and a significant pH sensitivity.” As time went on, adhesives’ pH resistance improved as well as the water reduction content of water-based adhesives. “It isn’t uncommon to find water-based adhesives with a solid content of 94 percent. However, blended chemicals cut with ash or slag can give a false sense of security due to the fact that their use will drop the pH of the Portland cement.”’
Morris said the cost of moisture-related failures is generally acknowledged to be approximately $1 billion annually. “By virtue of that staggering figure alone, moisture mitigation has placed itself front and center within the industry as a topic that must be addressed and more so than ever, planned for.” Morris urged the flooring industry to continue to develop solutions for dealing with excess moisture, as well as educate specifiers, architects, designers and general contractors on the potential threat to their project and plan to deal with it accordingly.
When and Why to Test. Moisture mitigation products are not 100 percent foolproof and there are times where the products can either be pushed to their limits or fail. “Not all products are created equal. Some systems require extensive floor preparation,” Glennon noted.
Erik Kurtz, market manager of Bostik’s hardwood installation systems, said some of his company’s products can offer protection against unlimited levels of moisture vapor transmission so no concrete moisture testing is required. However, he stated in extreme circumstances (e.g., flooding or an increase in height of the water table) hydrostatic pressure may develop and force liquid water up through the slab that could lead to the failure of products designed for even the most extreme moisture vapor conditions.
There are several scenarios in which a moisture mitigation product can fail, said Mark Lamanno, technical market manager of flooring, Franklin International/Titebond. “I have seen moisture come between the moisture mitigation product and the interface between the products and the floorcovering. A grading issue can be to blame. It is imperative the flooring installer as well as the estimator look at all conditions and site issues that might result in unsuitable flooring, regardless of a moisture remediation product. Those conditions must be brought up to the building standards as required by the flooring manufacturer as well as to local building codes.”
Taylor said since hydrostatic pressure cannot be stopped by moisture mitigation products, testing the floor is advisable even if there’s already a plan to use a barrier. “If water is coming to the surface of the concrete, the barrier will fail. Installers and property owners need to understand the moisture conditions to make the most educated decisions.”
However, Jeff Johnson, MAPEI business manager for floor covering installation systems and surface preparation products, said if a product is being used that claims efficacy on concrete slabs at full moisture limits (25 lbs. MVER and 100 percent RH), then testing is not always required. He added, “If you are using adhesives or other systems where limits are expressed in the technical data sheets, testing is most definitely required.”
One issue with moisture testing, Johnson said, is some contractors do not want to budget in the expense. “On a large project, testing can get to be a very expensive proposition. On a small job, it can chew into the overall profit. Contractors have been known to roll the dice on testing smaller projects and elect not to test. The consequences of not testing can result in the contractor owning the replacement costs which can be three to four times the original install. Not a good situation.”
Mark Long, technical director, Stauf USA, believes moisture testing should always be performed. “Be proactive and properly test before you have a problem. Once you know the level of moisture, then you can determine the best method for preventing [moisture] problems.”He added whether or not contractors believe they have the means to test, it’s everyone’s responsibility, and that it is critical to know moisture levels before starting a job in order to determine what product can be used to protect against those levels.
When testing, it is also important to know the similarities and differences between the kinds of tests available. ASTM F1869—the calcium chloride test—measures a subfloor’s moisture vapor emission rate. ASTM F2170—using in-situ probes—measures the relative humidity of the slab. Jason Spangler, flooring division manager for Wagner Meters, said it is hard enough getting people to do one test, so thinking they would do both is a pipe dream. “One issue I have with potentially doing both tests is asking, ‘What will people do if the results don’t agree?’ and many times they don’t. That is why picking the test with the most credible pedigree—RH testing—makes the most sense. Most installers aren’t getting paid to do any moisture testing, so getting them to do more takes additional money out of their pocket.”
Andrew Rynhart, managing director, Tramex Meters, explains the difference between the two tests. “Calcium chloride tests are intended to measure the potential rate of moisture released from the slab. This information could be useful to determine the potential time it could take to dry out the slab rather than mitigate the moisture. In-situ RH testing indirectly measures the moisture content from within the concrete and thus assesses any potential problems which could occur once the floor covering has been installed, and so helps flooring professionals avoid moisture-related problems.”
Spangler noted there are some mistakes that are commonly made while performing both tests. During calcium chloride tests, these mistakes can include not grinding the surface of the concrete properly, not waiting the whole 24 hours after grinding to test and not grinding a large enough area. For the in-situ RH test, common mistakes include not waiting long enough prior to getting an RH percent reading after installing the sensor, and drilling the hole to the improper depth.
Rynhart said it is also a common oversight to choose locations for either type of test without first carrying out non-destructive ASTM F2659 tests to moisture map the subfloor. “This test method allows the user to determine where to set the probes or boxes, and it can indicate what the eventual results will be of these tests.”
Grete Heimerdinger, vice president, Lignomat, said, “To follow the correct test procedure, the protocol needs to be followed and enough time needs to be allowed. Most importantly, the site has to be at service conditions which means the heat or air conditioners need to work, and doors, windows and roofs need to be in place.” She said given the choice, she would pick the in-situ RH test because the calcium chloride test can give false positives.
“Only proper testing can determine the amount of moisture protection needed. Most adhesives offering subfloor moisture control have limitations on the amount of subfloor moisture protection they provide,” said Duane Reimer, technical director, MP Global Products. He added if moisture emission readings are greater than the protection provided, an additional moisture control product may be needed.
When checking a wood flooring product’s moisture content, Rynhart said he would favor a combination of using both types of wood meters—pin and pinless. “Pin-type readings tend to be more accurate but only allow the user to test a very small area. Whereas the non-destructive, pinless meters read a large area in a short time. By initially carrying out non-destructive tests, one can reduce the number of pin readings to areas of high and low readings and anomalies, allowing all of the wood to be surveyed in a short time.”
Heimerdinger said choosing which type of meter to use comes down to an installer’s preference, though both have their advantages. “Most floor installers use both types of meters. Flooring is especially suited for a pinless meter because it’s always flat and not thicker than 3/4 inches.”
Spangler noted Wagner Meters only manufactures non-destructive meters because he believes an installer can read more wood with less time and effort, and with the same degree of accuracy. “You are able to do all of this without damaging one inch of flooring product. One area where a pin meter may have some advantage is in a forensic application where there is severe cupping or crowning that will not allow a non-destructive meter to sit flat.”
Concrete floor specialist Peter Craig emphasized the importance of moisture testing certification and training, stating it is essentially a validation that a moisture-testing technician has satisfactorily demonstrated their knowledge of and ability to properly perform each of the moisture test methods in strict accordance with ASTM standards.
Those who take the International Concrete Repair Institute (ICRI) Concrete Slab Moisture Testing Certification course, where Craig is an instructor, often learn aspects of the test methods that they have never known or been exposed to before, he said. “The test methods and the science behind them are explained such that attendees learn what affects the test results and what the results do and do not mean. Where subjectivity exists in a test method, specific guidance is provided. Students who successfully complete the course are in many ways better prepared to provide their clients with the most reliable data and information possible.”
Possible Solutions.When choosing between a surface membrane or applied barrier, Johnson said it comes down to site conditions. “If the moisture test results on the concrete slab exceed those limits of the floor covering, then a membrane should be applied. If a project is on a fast-track production schedule and there is no time to wait for the normal concrete curing process to take place, then a moisture barrier should be installed.”
There are many adhesive products available as moisture mitigation solutions as well, but it is essential the contractor is certain they provide the client with the specific needs of their project, said Brian Cordak, architectural representative for USG. “A good approach to determining the suitability of any given product or technology is to thoroughly read the performance criteria and capabilities of the product.”
Cordak said warranties should be scrutinized very carefully to ensure it is known specifically what is covered, and exactly what performance claims are being made for any offering. Many of the “higher-limit” moisture protection adhesive products are not a moisture or alkalinity barrier and make no claim to be able to stop or slow vapor transmission, and they also do not claim to prevent alkalinity from affecting the adhered system, he added.
Larry Scott, DriTac vice president of field technical services, said his company’s DriTac Golden Bullet 4141 offers unlimited subfloor moisture control in a single-component, premium-grade, four-in-one, sound- and moisture-control wood flooring adhesive. “This zero-VOC, zero- solvent multi-faceted product simplifies wood flooring installations when sound and moisture control is needed.”
Lamanno said it is good practice to use adhesives that include moisture remediation properties. “We do not know when moisture may come from the slab. The old adage that ‘a test done today is only good for today’ is very true. We know conditions in the soil based on higher elevations of moisture can lead to problems with any floor covering. A skilled installer that works in the same geographical area tends to know where the ‘hot spots’ of a given area are. If the installer is unsure, he or she should conduct testing and/or apply a moisture remediation system.”
Johnson stressed it is important to use caution when analyzing moisture claims on adhesives. ”These adhesives can withstand elevated moisture conditions and provide a bond such that it will perform at these levels, but do not expect them to act as moisture barriers. These adhesives are also tied to very strict pH limits. High moisture is one thing but with an associated high pH greater than 11, these high-performance adhesive products are going to struggle to maintain performance.”
Lamanno noted every floor covering job will be subjected to capillary action—the behavior of water to flow into small spaces even without the assistance of gravity—at some time in its life. “Why not use a moisture remediation system for every floor? Seems obvious.”