What is an acceptable moisture level in concrete floors or slabs?

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3.5 to 4.5 % Moisture Content

A new concrete slab can be considered ‘dry enough’ to receive a floor covering or coating when the moisture content is measured at between 3.5 and 4.5 % Moisture Content.

On clean new concrete 4.5% MC is considered "dry enough" in most ambient conditions. In drier ambient conditions, 4% concrete MC is considered "dry". In desert-type conditions generally, 3.5% is considered "dry". If the concrete moisture content is higher than this recommended amount, there is a chance that the moisture can cause damage to a floor covering, such as wood flooring or coatings, and lead to a costly floor failure.

Calibrated to read moisture in concrete 

To ensure accurate and trustworthy %MC reading results, it is essential to use a quantitative concrete moisture meter that is calibrated to read percentage moisture content in concrete. The Tramex Concrete Moisture Encounters CME5 and CMEX5 are specifically calibrated to measure moisture content % in concrete floors and slabs based on gravimetric testing.

Concrete moisture measuring

The Tramex concrete moisture meters read 3/4” deep into the concrete slab giving instant, reliable quantitative results and when coupled with the Tramex Concrete Moisture Probe (the Determinator) can read up to 4” deep in the concrete slab giving correlating %MC readings.
Correlating measurements on the surface and deep into the slab allows for an instant determination of moisture content levels throughout the slab. 

Tramex has been a well-established and authoritative brand name in the world of concrete moisture testing for many years. In addition to from reliable concrete moisture meters, Tramex has also developed multiple Concrete Moisture Test Kits for performing particular concrete testing methods at the different stages - pre-installation of subfloor moisture testing, testing at the time of floor installation, and post-installation concrete slab moisture remediation. 

The Flooring Installation Quick Check test has been developed for flooring installers to ensure conditions are correct for a successful and long lasting floor installation. This method can be easily carried out with the Flooring Installation Quick Check Kits.

The Complete Concrete Moisture Test System was developed by Tramex to allow for the most comprehensive, in-depth moisture evaluation of a concrete floor or slab and can be carried out at any time either on a new or old concrete. This method includes the ASTM F2170 test for in-situ relative humidity testing of concrete slabs.



Below is the transcript of the video interview with Robert Higgins - Tramex Talks

David: Hi Bob.

Bob: Hi David.

D: Thanks for joining us again on Tramex Talks.

B: Thank you for having me.

D: Today's question is: what is an acceptable moisture level in concrete?

B: What I found, if you use a Tramx meter, most of the time unless you're in the desert, about 4.5% it's fine. 1.5% lower it's fine, that's dry enough. Especially in Florida, 4.5% is real dry. If you getting into the desert areas probably closer to 3.5%.

D: And will that number generally change on older concrete?

B: Yeah, because older concrete gradually becomes dryer and dryer as it continues to develop cement, and the chemistry redistributes, but again this is where you want good concrete practices. If the concrete has not been cured properly, a lot of the problems that we see with newer concrete get worse with age.