Debunking common myths about concrete moisture mitigation
A conversation with David Seland of ISE Logik Industries, Inc.
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 floor covering is vital for full long-term protection.
This article first appeared in Premier Flooring Retailer in the Fall 2020 issue