Test concrete slab moisture with ASTM F2170 RH probes to diagnose a possible waterproofing/vapor-barrier deficiency (not a flooring-install spec)

Steps

1. Use ASTM F2170 (Determining Relative Humidity in Concrete Floor Slabs Using In Situ Probes) to characterize the slab's internal moisture condition before assuming a flooring/coating failure is purely a materials issue — the goal here is distinguishing an ongoing moisture-source problem (missing/failed vapor retarder, exterior drainage defect, high water table) from a one-time residual-construction-moisture condition.
2. Follow the core procedure: drill test holes to 40% of slab thickness (20% if drying from both top and bottom), at a minimum of three locations for the first 1,000 sq ft under investigation (more for larger areas), and clear holes of dust/debris before inserting probes.
3. Condition before reading: bring the slab and air above it to normal service temperature/humidity for the specified period (commonly 48 hours), and allow each drilled hole to equilibrate (commonly 24 hours) before taking the reading — a hole read too soon reads artificially low.
4. Treat persistently elevated RH (despite adequate slab age/drying time) as evidence of an ongoing moisture source requiring investigation — cross-reference the under-slab vapor retarder's presence/class (ASTM E1745) and exterior drainage/waterproofing condition rather than treating the RH number alone as a complete diagnosis.
5. Keep this workflow scoped to the diagnostic question — specific flooring adhesive/product moisture-tolerance thresholds and mitigation coating selection belong to a separate flooring-installation topic; this route stops at what the slab's moisture condition indicates about a waterproofing deficiency.