RH Probe (ASTM F2170)
A probe measures relative humidity inside the slab at 40% depth. It's the gold standard test and correlates well with long-term vapor performance.
Calcium Chloride (ASTM F1869)
A dish of anhydrous calcium chloride sits sealed on the slab for 60-72 hours. The weight gain calculates moisture vapor emission rate (MVER) in lbs/1000 sq ft/24 hrs.
What the Numbers Mean
- RH under 75% — standard primers work
- RH 75-85% — moisture-mitigating primer required
- RH over 85% — heavy-duty MMP system required
- MVER under 3 lbs — standard install
- MVER over 3-5 lbs — MMP required per system spec
When We Test
Basements, older slabs, ground-floor commercial, and any project where the client reports past moisture symptoms. We include testing in the quote when relevant.