Common myths about concrete moisture and mitigation
A: In my 20+ years as a flooring claims investigator and my role since then as founder and principal of ISE Logik, I’ve encountered a lot of misconceptions about moisture and concrete. (In fact, some of these have been held by people you think would know better!) In our company, our business is to help everyone in the flooring and construction industry avoid the time consuming and costly impact of vapor transmission through concrete slabs with both our admixture formulas and topical coatings. Over time, moisture can simply ruin a beautiful flooring installation. So, we know all the ins and outs about moisture—we have too!
Q: What’s a common misconception when the concrete surface is wet?
A: That the moisture is coming from the concrete. In many cases, it may simply be from moisture in the air. Condensation. Check the dew point and ambient conditions and if 50 Fahrenheit or less from dew point. This is common with jobsites where the ambient conditions are not effectively controlled. (Note that as time progresses during the day and the dew point spread increases, resulting in evaporation, the concrete surface will become dry.)
Q: What are some common moisture testing errors or misconceptions?
A: There are four common mistakes that come to mind. First, moisture tests are often conducted when the jobsite is not at service temperature and relative humidity for occupied normal use. When this happens, it goes against ASTM requirement. Secondly, the required number of tests per ASTM is three tests for the first 1000 ft2 and at least one additional test for each 1000 ft2 thereafter. This required number of tests is not often done, especially on larger projects.
Thirdly, another misconception is the belief that new concrete will even pass the moisture tests. Basically, unless many months of very favorable drying conditions are provided (HVAC running; and which projects don’t have), it is unlikely that new project concrete slabs will meet the flooring industry requirements. Lastly, and perhaps the biggest error is that moisture tests are predictors of resilient flooring success; this is simply not the case. ACI 302.2R-06 pointed this out and reported that there is no correlation between the relative humidity of the concrete and adhesion of resilient flooring.
Q: What’s the latest misconception?
A: One that we’re hearing a lot more lately is that using a high-moisture tolerant adhesive will adequately protect you. If a 95% or even a 99% RH tolerant adhesive is used, what occurs when the RH of the slab increases above that with a failure present? The building owner now has a failed system that offered only partial protection going in. This is why utilizing a moisture control system that covers to 100% RH and blocks the moisture from adversely affecting the floorcovering is vital for full long-term protection.
More information about concrete moisture and mitigation can be found at ISElogik.com
About David P. Seland
David Seland is a Principal and Founder of ISE Logik Industries. Over the past 35 years he has worked in a wide range of positions in the building products industry including floorcoverings, coatings, and substrates. As one of the top independent building products failure analysts focused on coverings and coatings applied to substrates, David directed over 5,000 on site field inspections throughout the Americas for product manufacturers, project owners, and construction managers. David’s expertise and determination for innovative and proactive solutions for concrete moisture control led to the formation of ISE Logik Industries – dedicated to stopping moisture vapor in its tracks.