Concrete Moisture Testing with In-Situ RH Probes
Before installing resilient floor coverings or applying coatings over concrete, it’s critical to know how dry the slab is inside – and not just at the surface. Learn how in-situ relative humidity (RH) testing works, when to use it, and what tools you need.
Why Moisture Measurement in Concrete is Essential
Excess moisture within the slab can rise to the surface and lead to problems with floor coverings and coatings.
The in-situ RH concrete moisture test is described in the ASTM F2170 standard.
Concrete takes time to dry – use the reliable in-situ RH test to confirm dryness before installing floor coverings.
How In-Situ RH Probes Work in Concrete
RH probes are placed inside sleeves at a defined depth.
The measured RH value correlates with the internal slab moisture content. Acceptable ranges are set by the floor covering, and epoxy manufacturers.
This method is recommended by the floor and epoxy manufacturers because it delivers the most reliable results.
In situ RH testing is the industry standard for determining if a concrete slab is ready for adding the floor coverings.
Common Use Cases for Concrete Moisture Testing
Commercial Flooring Installation
Ensure slabs are ready before laying vinyl, wood, or tile.
Basement & Residential Projects
Prevent flooring failure from hidden moisture below grade.
Lab and Facility Construction
Meet strict material tolerance specs for hospitals and labs.
Water Damage & Remediation
Confirm moisture levels after a leak or flooding event.
Recommended Lignomat Tools for Concrete
The RH BluePeg System provides reliable, ASTM-compliant in-situ testing for concrete slabs.
It pairs with the Ligno-VersaTec, Ligno-DuoTec or Ligno-Tec RH which display RH readings. For Data Logging and monitoring we offer the BL2-RH data logger.
How to Perform In-Situ RH Testing
1
Depth of hole should be 40% of slab thickness for a slab drying from one side. Clean with brush and vacuum.
2
Insert RH sleeve with cap, before drilling the next hole.
3
Insert RH BluePeg probes 24 hours after sleeves have been placed. Wait for probes to be acclimated.
4
Check for drift. Drift should be no more than 1% RH over 5 minutes. Record measurements.
For valid results follow the ASTM standard F2170. Standard can be downloaded from the ASTM Web-site.
Make Sure Your Slab Is Dry—Inside and Out
Surface meters alone won’t give you the full story. For accurate concrete moisture testing that meets industry standards, choose Lignomat’s RH BluePeg System and trusted moisture meters.