Concrete Moisture: Contractors weigh in on current moisture issues plaguing concrete - June 2018
Floor Focus consulted four commercial contractors, two Fuse Alliance and two Starnet members, to provide insight on the latest concrete moisture issues, the technology currently used to help remedy these issues and the changes they are seeing in the industry. The concrete panel includes Tom Sheridan, CEO at PCI FlorTech in Addison, Illinois; Todd Bircher, executive vice president at Floors, Inc. in Omaha, Nebraska; Jon White, president/co-owner of Paul G. White Interior Solutions in Portland, Maine; and Andy Meyer, COO at Flooring Systems in St. Louis, Missouri.
How often is concrete moisture an issue on the projects you work on?
Tom Sheridan: The only time concrete moisture becomes an issue is when the general contractor and/or end-user fail to plan for the possibility of needing to use a moisture reduction barrier. We are very proactive in discussing and planning for moisture issues from the first time we are brought into a new project. Three years ago, we were having issues every two to three weeks on projects. Now, we have issues every two to three months.
Todd Bircher: Concrete moisture is an issue on most projects. It becomes a concern 40% to 45% of the time because readings are high. Most of these moisture readings land at acceptable levels as job sites mature (and slabs have more time to acclimate). Concrete moisture impacts our installation methods and/or the products we employ 15% to 20% of the time.
Jon White: In the Northeast, we see moisture issues to some extent on 75% of new projects.
Andy Meyer: Approximately 70% of the projects we work on in the Midwest experience moisture issues.
Q: What are the primary causes of concrete moisture issues?
Bircher: With new construction, the primary cause of today’s moisture dilemma is project timetables. Projects that required 16 to 18 months in the 1990s are now completed in less than a year. Frequently, there is not enough time for slabs to dry as they should. Power trowels make it possible for Division 3 tradesmen to more efficiently complete their work. The problem is that they can reduce slab surface porosity. Consequently, moisture needs more time to work its way out. Renovations/trenches have different issues. Poorly installed vapor barriers are a significant issue in renovation work and can also be a problem with trenches.
Sheridan: We find that the main causes are a blend of the fast-track construction schedules combined with new concrete that has been trowel finished to a shine. The fast-track schedule doesn’t allow enough time for the moisture levels in the concrete to drop to acceptable levels, and the hand-troweled surfaces tend to inhibit the release of the moisture.
White: The primary issue with moisture is the schedule. We are expected to install flooring in a very short time, which is usually shortened due to other trades or setbacks.
Meyer: We are seeing condensed construction schedules and burnished concrete as some of the primary causes. Also, old concrete slabs without a functioning vapor retarder can lead to moisture issues.
Q: How is this changing over time?
Bircher: At one time, changes in the chemical makeup of adhesives and backings were major contributors. This improved as manufacturers enhanced their offerings. Today’s issues are different.
White: This seems to be getting worse in our area. Tighter construction schedules are a major factor; buildings are closed in with HVAC systems running for a very short window. Owners want a quick turnaround after they make an investment, and this conflicts with a proper cure time.
Sheridan: The fast-track construction doesn’t change, and, at times, it seems as if they are trying to reduce construction schedules even more. We have been working with a variety of general contractors, architects and end users, educating them as to what can be done to minimize the moisture-related issues that were running rampant several years ago. At the top of this list is the recommendation that the new slab be left with a Concrete Surface Profile of CSP2 to CSP3 [degrees of concrete surface roughness], which has reduced the number of projects that require any type of moisture mitigation.
Q: Do you feel like the incident rate is rising?
Bircher: The incident rate increased several years ago when petroleum-based products were banned. It also increased over the years as construction timetables became more compressed. In recent years, flooring failures have become less prevalent in our practice.
High moisture readings have been common for a long time, and they seem to be getting a little more frequent. Time is money for general contractors and property owners.
I think we are learning to address the issue as an industry. Special adhesives and better moisture control systems add cost and time to projects, but they definitely work. Many people have come to understand that moisture-related flooring failures cost a lot more than the costs associated with addressing the issue before floors are installed.
White: We see the moisture issues increasing in our area; the ability to substitute moisture resistant adhesives does allow for installation without mitigation. The construction industry including owners, architects and general contractors are more aware of potential failures and relative humidity (RH) requirements.
Meyer: Over the course of the last five to eight years, we’ve experienced roughly the same rate of incidents. The one change is that there is an increase in renovations of existing buildings and many of those do not have the functioning vapor retarders.
Sheridan: It has been our experience that the incident rate is going down. I believe that is a direct result of the collaboration between our firm and the general contractors, architects and end-users that we work with. Again, it is an education issue. Fifteen years ago, we were educating our clients about moisture issues. Now, we are educating them about best practices to try and avoid the moisture issues.
Q: What testing method do you prefer? Are there new tools that give more accurate readings, eliminate variables or expedite the process?
Sheridan: We prefer and strongly recommend independent third-party testing for all of our projects. When pressed into service, we use RH tests in all instances. Currently, we use either Lignomat RH probes or Wagner’s Rapid RH probes.
Bircher: We employ whatever testing tools are necessary to meet product specifications. A combination of calcium chloride testing and RH testing using in-situ probes is most common. We rely heavily on Wagner’s Rapid RH testing probes. They are easy to use and provide reliable readings.
White: We have three ICRI (International Concrete Repair Institute) concrete slab moisture testing technicians, and we are certified in all types of testing. However, we recommend the Wagner Rapid RH testing probes in accordance with ASTM F2170. Most of the manufacturers require this test in their literature.
Meyer: We use the in-situ probes-mainly the Wagner Rapid RH system.
Q: Are there any new floor prep solutions that allow you to move forward and complete the job?
Sheridan: We have always used a moisture reduction barrier (MRB) as the solution to high moisture conditions. There are a variety of adhesives that are now available that we can use with moisture readings of 90%, 95% and even 99% with some products. For situations where we use a moisture barrier, the one we have been using is Chapco’s Defender EZ. This MRB is less costly than most MRB products and is just as successful in controlling high moisture conditions.
White: The way we warranty a floor, along with the manufacturers, is to mitigate the concrete slab. There are methods that we can employ earlier in a project to eliminate the meetings and arguments regarding mitigation. That involves the concrete finisher just providing a broom finish or simple finish. We would then shot blast seven days after the concrete is poured, mitigate the concrete with a two-part epoxy mitigation system, apply a self-leveler, and eliminate all the testing and waiting.
Meyer: There is an increase in the number of high moisture adhesives now available. Also, new products that have higher moisture limits, such as carpet tiles with breathable backings and alternative adhesives such as TandusTape and Shaw LokDots, allow us to mitigate moisture issues and move forward with the job.
Bircher: Oftentimes, the best alternative is simply giving a slab time to dry. Unfortunately, tight schedules might not allow natural drying. Solutions include sealing the floor with a moisture control system, using moisture resistant adhesives, employing adhesive tabs to create a floating floor or using a rolled moisture barrier. If a slab is too slick (due to power trowels), grinding or blasting it can accelerate drying. It is worth mentioning that moisture-resistant floor patching compounds are available and can accommodate flooring installations within a few hours.
Q: Are some flooring types more forgiving to moisture issues than others?
White: We are concerned with just about every flooring type as far as moisture is concerned. There are some that are click floors or loose lay that possibly could be installed without concern. However, there are other issues that a lot of flooring contractors do not consider. With carpet, there is the mold issue. With ceramic tile, grout discoloration and membrane failures are likely to occur due to the moisture issues in the concrete. Also, when moisture leaves concrete, salts and contaminants rise to the surface that may break down adhesives.
Sheridan: The product that comes to mind are carpet tiles with open cell cushion backing, such as Milliken carpet tiles. This type of construction allows the water vapor to travel through the carpet tile backing and evaporate away.
Bircher: Floating floors and carpet products with breathable backings are helpful when high moisture is present. But they are not moisture proof, and they can be susceptible to mold. Keep in mind that plastic chair mats and flat bottom furniture defeat the moisture resistant qualities noted here.
Meyer: Most flooring types are very moisture tolerant. Even if installed in areas where the moisture level exceeds the manufacturer limits, there are few failures. Those that are the highest risk are the sheet products and rubber products. Also, manufacturers are introducing new environmentally friendly products that tend to have a higher rate of failure as a result of the new materials not having the extensive use/testing of materials that have been used for years. Generally, anything modular installed with a pressure sensitive adhesive tends to fare well in a high moisture setting.
Q: Is there anything a commercial flooring contractor can do to ensure moisture issues are lessened moving forward?
Meyer: There is a lack of understanding on how to properly perform moisture testing. Being more cautious and efficient with testing methods will help more accurately identify the problem in concrete slabs.
Sheridan: I would suggest continuing to educate the architect and general contractor in regard to the new concrete slabs and how they are finished. The concrete contractors follow the guidelines established for floor flatness and smoothness, which generally results in slabs with a highly polished look that trap moisture with no way of escaping. We urge that the concrete slabs be left with a rougher finish [CSP2 or CSP3] so that we are giving the slab the best chance possible to release the water vapor. The minor floor preparation that is required to achieve a smooth floor is inconsequential when compared to the cost of moisture remediation.
Bircher: Nobody wants moisture problems, so avoiding them in the first place is vital. More education is needed. We should commit, as an industry, to helping general contractors, architects, designers and others understand the causes and solutions related to the concrete moisture problem.
White: With today’s adhesives, the need to test and be very cautious of installs is a must. Until we see adhesives being developed without concern for moisture, it must remain at the forefront with commercial flooring contractors getting involved and voicing concerns as early as possible.
Q: Is there any way to insulate yourself from liability if the general contractor is insistent that you move forward with the flooring installation?
Sheridan: No, there is no way to insulate yourself from liability if you proceed with the installation and do not address the moisture issues. No matter what releases are given and agreements are discussed, if an issue goes before a judge, it will be a simple question from the judge: should you, as a professional, have proceeded with the installation knowing that the high moisture issue conditions were present? Our company policy is simple when this condition arises. We point out that they are trying to push us into not following the guidelines established by the manufacturers for the installation of the flooring materials, and we cannot proceed until the issues are addressed. Our firm will not install flooring over high moisture areas unless the moisture has been addressed.
Bircher: Legal waivers are effective but only if signed by all parties. As a quality flooring contractor, we only proceed in these situations if risk of loss is low. It is unconscionable to install a floor that you believe is going to fail. In that case, it is best to record your concerns and walk away.
White: I would like to say we will never install without an owner signoff, but there have been a few occasions we have. In those cases, we have lawyers write agreements between all parties, including the general contractor, owner and architect. Those three are usually very reluctant to sign a release, which pushes us back to the table for a better solution.
Meyer: We make sure the situation is documented as thoroughly as possible. We do have a waiver that we get signed by the responsible parties, but that is not foolproof.
Q: In new construction scenarios, are the Division 3 contractors doing a better job of proactively eliminating issues at the onset?
Bircher: They are trying, but construction project schedules are tough. Overwatering concrete, overusing power trowels and increasing the size of poured sections is further complicating flooring installations. Division 3 contractors are doing a nice job following vapor retarder installation standards, which is imperative to the long-term success of on-grade slabs.
White: The only thing the concrete contractors can do is use a proper vapor barrier, use the correct mix when installing and use the proper curing process. The schedules that we are faced with make the concrete virtually impossible to reach proper RH levels. The concrete needs to be kept out of the weather and in a somewhat controlled environment. Today’s schedules do not allow for proper drying time or the required conditions for installation.
Meyer: It depends on the quality of the general contractor. The GC dictates this. But the generic answer is no; they are not doing a better job.
Sheridan: I don’t believe that this is entirely a Division 3 contractor issue. They are just following the specifications provided. To be more proactive, the architect/general contractor needs to get Division 3 contractors together with Division 9 contractors at the design stage to develop a plan of action for the project to minimize the potential of moisture issues. With that said, I would also strongly advise that every project may have the potential for a moisture issue; plan for the moisture issue early and include an allowance for mitigation costs in your budget.
Q: Who serves as your advisor for information and advice related to concrete moisture?
Sheridan: I have found the technical representatives for the manufacturers to be a great resource. Our number one advisor would be HB Fuller. We have used the Chapco Defender moisture reduction barrier on over 1.5 million square feet and have never had a moisture-related failure on these projects. Over the years, we have encountered projects with unique challenges associated with the moisture issues, and Chapco has continually worked with us to develop system solutions for each project.
Bircher: In addition to the years of industry experience our team possesses, we rely on various industry experts and continuing education. Some of the best resources we have include consultants from Fuse Alliance and the International Concrete Repair Institute. We also depend on manufacturers to clearly explain and document the moisture sensitivity of their products. We are fighting a losing battle if manufacturers are unclear or if they share inaccurate specifications.
White: In our company, I serve as the lead on any mitigation project. We have three inhouse technicians who are able to place test and verify readings. On large projects, we recommend a third party to handle all testing; where we sell mitigation, it can be seen as a conflict. As far as outside resources, we belong to the International Concrete Repair Institute. We also work with our vendors to find solutions to problems as well as with Peter Craig, concrete floor specialist with Silpro, in extreme cases.
Meyer: Fuse provides some experts for us to contact and discuss issues with on an as-needed basis. However, I try to stay up on all current happenings on this issue, so I can provide value to my customers.
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