When it comes to concrete moisture testing in commercial construction, it might be tempting to simply buy a commercially available concrete moisture testing product and do it yourself. It’s as simple as taking a reading, right?
Not so fast.
Handheld Meters Show Moisture at a Glance
The quick and easy way to check a concrete slab for moisture is to use a handheld moisture meter. There are two types of these meters. Pinless meters use radio frequency signals to detect moisture near the surface of the slab. Pin-type meters use electrodes driven into the slab to measure beneath the surface.
But besides the fact that neither type of meter is especially accurate, the data from these meters cannot be used to certify that flooring has been installed per the warranty requirements. To ensure the validity of the manufacturer’s product warranty, much more sophisticated testing methods are necessary.
Still, the question is:
If you needed X-rays to determine the cause of an illness, would you have a medical team do it, or would you have your dental hygienist take a stab at it?
The truth is, the dental hygienist probably knows how to take an X-ray. But beyond that, the knowledge required to examine and evaluate the results of the X-ray is completely different.
The same is true for concrete moisture testing. There’s much more to it than meets the eye. What many don’t know is that the data from improperly conducted moisture testing is actually invalid. That means that a product warranty can be invalidated, and liability for a resulting flooring failure can be placed on the person who conducted the tests.
So although concrete moisture testing products are commercially available, there are many reasons why it’s not in the best interests of the responsible parties to be the ones to conduct these tests.
Testing must conform to the most current ASTM Standards to produce valid concrete moisture testing data. ASTM F2170 Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes.
Testing with this method will provide valuable information about how much moisture is within the concrete. Detection of concrete moisture levels only at the surface of your concrete does not provide an adequate assessment, which is why it typically makes sense to test for relative humidity (RH) in addition to calcium chloride testing.
Relative humidity (RH) testing has been common practice outside the United States since the 1980s. It wasn’t until 2002 that the test became an ASTM recognized test. Since then, much research and field data has been obtained, and today almost all product manufactures recognize this test method for warranty purposes.
This test is conducted by drilling a hole into the body of the concrete and measuring the relative humidity at the bottom of the hole using a probe. A recent update to the ASTM standard has reduced the minimum equilibrium time to 24 hours, making this test more viable in time-sensitive situations.
Other ASTM F2170 standards for testing:
- The site must be at normal operating conditions.
- Windows and doors have been installed and enclosed
- HVAC system is up and running
- The building temperature and relative humidity are at the expected normal operating conditions for a minimum of 48 hours prior to and during testing
Proper documentation of test results for all tests:
- Start date and time of testing with ambient temperature and humidity.
- Finish date and time of testing with ambient temperature and humidity.
- Date and time hole was drilled
- Date and time sleeve was placed
- Date and time probes were placed
- Date and time probes were read
- RH % of the probe
- Temperature of the Probe
Regardless of the relative humidity test method you’re using, if you’re obtaining your readings from anywhere but correct depth, you may not be adhering to the ASTM F2170 standard in every test situation. These probes must be placed at a depth equal to 40% of the thickness of the concrete for a slab with one side exposed; 20% if two sides.
Proper calibration of probes
With re-use, relative humidity probes used with the older, separate sleeve/probe method can become decalibrated due to contaminants and other environmental factors, potentially resulting in wildly inaccurate results. According to Section 8 in ASTM F2170, verifying a probe’s measurement accuracy requires testing the probe with a salt solution or with a humidity chamber.
Probes must be checked for calibration at a minimum of every 30 days. To confirm that the probe has reached temperature and humidity equilibrium with the concrete, ASTM requires no more than 1% drift of RH reading over 5 minutes.
Proper testing methods include detailed photos of the testing site, including pictures of the flooring in place, places where there is any indication of a flooring failure, and places where the flooring is intact. Photos should also document each of the multiple test sites.
Beyond the execution of the testing itself, other factors that should be considered when conducting tests:
Errors and Omissions insurance
Errors and omissions insurance protects professional advice- and service-providing individuals and companies in the case of a negligence claim made by a client, and covers damages awarded in such a civil lawsuit. In other words, if a business suffers a financial loss caused by an error or omission in the service or product sold by the policyholder, those losses can potentially be recovered.
Many concrete moisture testing professionals are not backed by errors and omissions Insurance. This means that there is no legal recourse for the possibility that the information they provide is inaccurate, and may result in a financial
With the rise in litigation surrounding the construction industry as a whole, the importance of E&O insurance can’t be overstated.
Avoid conflicts of interest
When concrete moisture tests are conducted by a flooring installer or other industry professional who profits from selling flooring products, questions of validity can arise when test results indicate the need for those products. But when tests are conducted by an independent, certified concrete moisture testing professional, there is no conflict of interest. Whether test results indicate that moisture remediation is necessary, or that the concrete is in the appropriate condition for flooring installation, there is no reason to doubt the validity of the tests.
Avoid costly litigation
When floor-covering decisions are based on nothing more than a few simple tests – especially when conducted by persons who have no direct knowledge of concrete science, we should not be surprised by costly flooring failures and the litigation that often follows. To avoid that possibility, it’s in everyone’s best interests to hire a certified concrete moisture testing professional to conduct the tests.
For more information on unbiased concrete moisture testing methodologies, please take a look here or give us a call at 1-800-490-3657