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 for Accurate Moisture Readings in Concrete
For precise and dependable %MC measurements, rely on a quantitative concrete moisture meter specifically calibrated for percentage moisture content in concrete. The Tramex Concrete Moisture Encounters CME5 and CMEX5 are designed to measure moisture content % readings in concrete floors and slabs, aligned with gravimetric testing standards.
Measuring Concrete Moisture
Tramex concrete moisture meters penetrate 3/4" into the slab for immediate, dependable quantitative results. When paired with the Tramex Concrete Moisture Probe (the Determinator), they extend readings up to 4" deep, providing comparable %MC values. Surface and in-depth measurements enable quick assessment of moisture distribution across the entire slab.
Tramex has long been a trusted authority in concrete moisture testing. Beyond dependable meters, Tramex offers various Concrete Moisture Test Kits tailored for specific testing phases—pre-installation subfloor checks, time-of-install evaluations, and post-installation moisture remediation.
The Flooring Installation Quick Check test helps installers verify optimal conditions for durable floor installations. Perform it using the Flooring Installation Quick Check Kits.
The Complete Concrete Moisture Test System from Tramex enables thorough, detailed moisture analysis of concrete floors or slabs at any stage, new or existing. It incorporates the ASTM F2170 in-situ relative humidity test for concrete slabs.
This article is presented by Tramex, a global leader in moisture and humidity measurement for more than 50 years. Our engineers and industry specialists work alongside professionals in building inspection, flooring, roofing and water damage restoration to provide accurate and reliable information. With decades of experience and innovation in non-destructive moisture detection, we share practical insights backed by science and real-world experience.
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.