How to correct a dew point issue on a concrete slab

Video Link

This video guide explains how to address high moisture content readings in concrete floors or slabs that could be caused by dew point.

When a non-destructive moisture content reading, taken with a concrete moisture meter such as the Tramex Concrete Moisture Encounters CME5 or CMEX5, shows a high %MC, it could be due to a dew point issue.

This can be verified by performing the Installation Quick Check Test, see video here,  examining ambient conditions, including the ambient dew point and comparing this to the surface temperature of the concrete slab. If the surface temperature is within 10 degrees Fahrenheit or five degrees Celsius of the ambient dew point, there may be moisture in the slab.

To address this, air movement through the use of fans can be implemented to pull moisture out of the slab and return it to ambient conditions. If the ambient relative humidity is too high, dehumidifiers may need to be used. Once the fans have been implemented, the Concrete Moisture Encounter can be used again to get a percentage moisture content reading. If the reading is still too high, mitigation may be necessary.

Finally, it is important to note that even if the percentage moisture content is low, a dew point issue should still be addressed to prevent moisture-related flooring failures.

The Installation Quick Check test can be performed with the Tramex Installation Quick Check and the Installation Quick Check Plus kits.


Video transcript:

Today we're going to talk about what to do if you encountered a dew point issue when performing the Installation Quick Check. If you haven't seen the installation Quick Check video as of yet, you can follow the link below to check it out. 

When conducting the installation quick check the first thing we looked at was the ambient conditions including and noting the ambient dew point. Now this will be listed at the bottom of the CMEX5 as soon as you walk in the room, being picked up by this hygrometer. And we're going to compare that again to the surface temperature of the slab using an infrared thermometer, and we just are making sure that the surface temperature of the slab is at least 10 degrees Fahrenheit above the ambient dew point or five degrees Celsius above that ambient dew point. And this is going to ensure us that we don't have ambient moisture that's been drawn into the slab. Now if we are inside that 10-degree Fahrenheit or 5-degree Celsius cushioned, there are some simple tricks you can implement to pull that moisture back out of the top of the slab.

In this situation, your best friend is going to be air movement. And we can implement this pretty easily by using fans and running them across the surface of the concrete slab. What this does is it actually pulls the moisture back out of that surface area and puts it back into ambient conditions. If your ambient relative humidity is too high preventing the air from being able to hold any more moisture you may need to run dehumidifiers. And you should see generally within about an hour or so, you'll start to see some changes in those numbers. Now, once you've implemented the fans to remove the moisture from the surface of the slab, now we're going to follow with the Concrete Moisture Encounter, depressed to the surface, to get the percentage moisture content, and we want to see that that percentage moisture content has come down to an acceptable level for installation. If that number has not come down to an acceptable level for installation, this can be a sign that you may need to mitigate. 

Now, another situation could be that when I enter a job site I see that I have a dew point issue but I push my meter to the surface and I'm getting four percent as my percentage moisture content reading. So, the question would be does the dew point issue now matter? The answer is yes, you want to correct that dew point issue again with fans and then go back and test with the meter, and you'll see that that four percent has probably come down. Generally older concrete will have a lower percentage moisture content than a newer concrete. So, sometimes even seeing four percent with a cited dew point issue is indicative that there is some moisture up in that top one-inch portion of the slab that could affect your flooring installation.

By implementing this Installation Quick Check and understanding how to solve problematic dew point conditions, you can protect yourself against moisture-related flooring failures.