Are You Accountable for Moisture Tests (Measuring RH) in Concrete Floors or Slabs?

Relative Humidity Measurement

Whenever there is a discussion about measuring %RH (Relative Humidity) in concrete floors, the question of accuracy frequently comes up. It’s always wise to get accurate moisture readings but, today the reasons for measuring the RH are many. These include:

Certification of the RH under a commercial contract, and is frequently verified by independent third-party inspectors
Ensuring proper RH is achieved in accordance with guidelines issued by manufacturer of the floorcovering or adhesive.
Compliance with certain materials warranties which could be voided if specific RH levels are not achieved
Simply to check that the moisture in the concrete has equalized or reached the level of stability needed to for construction to continue

The issue of accuracy has become far more important in today’s litigious society. No longer is it simply a matter of your reputation for good workmanship. It’s getting down to proof! This means:

Proof that RH tests were actually completed and properly recorded
Proof that your RH meter/sensor system is properly maintained and calibrated
Proof that you are tests were completed in compliance with a standard such as ASTM F 2170
Proof the test sites were properly installed and protected so that the RH readings were accurate

Every manufacturer has different equipment designs and recommendations for how the actual tests are performed with their equipment. However, in the end, the results should be comparable across all manufacturers under the same conditions. So understanding the equipment and testing procedures is the user’s responsibility.

Testing moisture in concrete floors and slabs has become a bigger responsibility since the introduction of standards like ASTM F2170 over 10 years ago. The reason is somebody down the line - perhaps next week, next year or even 10 years from now - might ask you to prove your RH tests were, in fact accurate and executed according to the standard. There are many places were just the slightest user error or defect can have a significant impact on the outcome of that inquiry.

Ten Easy Steps to Accurate Concrete Rh Readings

Here are 10 tips to comply with ASTM F2170-11 Standards:

When installing testing sleeves, you must first drill to the proper depth. Follow standard such as ASTM F 2170 other guidelines suitable for your particular application.
After drilling a hole, vacuum it out and inspect it so there is no excess dust or metal particle contaminants from reinforcement products. Contaminants and /or dust interfere with sensor performance. Vacuuming is required under ASTM F2170 guidelines.
Use the right sleeve for the location. Flush sleeves are less prone to damage or interference at an active worksite.
Ensure the sleeve has a tight fit so that humidity does not escape from the hole. The sleeve should be snug at the sides. Sealing the tubes flange at the top of the sleeve with silicon as its being inserted into the cleaned drill hole is recommended.(Sealing is required under ASTM F2170).
Use clean caps on the sleeve and make sure they have a snug fit so that humidity cannot escape and air cannot infiltrate.
In indoor applications, check the condition of the sensor that’s providing the Rh reading to make sure it’s not being contaminated by moisture off gassing.
Regularly check your device and sensor for contaminants, abrasion, or anything that may affect your readings.
Always follow the maintenance and calibration protocols for the RH meter you’re using.
Always check with the device manufacturer’s tech support if you have any questions about your readings or equipment.
Photograph and record the dates, times and testing conditions, then “file” them with the project records.

Conclusion:

Every situation is unique for Relative Humidity (RH) readings in concrete flooring and slabs. Some readings and controls have to be more exacting than others but accuracy is always import.

Use common sense and consider:

Where the floor is located
What is the intended use for the structure
Contractual requirements and specifications
Materials specifications for floor coverings and other materials
Operating environment for electrical equipment and controls
Other guidelines for whatever is being installed or building use

Ultimately, you need to be confident in the testing you performed. So follow the ten easy steps, because some day you just might be called on to “prove it”!