Concrete Floor Moisture Testing Workflow

Steps

1. 1

   Visual Inspection

   Check for visible moisture, efflorescence (white salt deposits), or dark wet spots. Note any standing water or recent rain exposure.

   Pro tip: Morning inspections catch moisture that evaporates by afternoon. Test early.

2. 2

   Plastic Sheet Test (Quick)

   Tape 18x18 inch plastic sheet to floor. Wait 24-72 hours. Check for condensation under plastic or darkening of concrete.

   Pass: No moisture visible\nFail: Any condensation or darkening\nNote: This is screening only, not definitive

3. 3

   Calcium Chloride Test (ASTM F1869)

   Place calcium chloride dish on clean concrete under sealed dome. Wait 60-72 hours. Weigh dish to calculate moisture vapor emission rate (MVER).

   Pass: < 3 lbs/1000sqft/24hr for most coatings\nPass: < 5 lbs for moisture-tolerant systems\nFail: > 5 lbs — do not coat

4. 4

   RH Probe Test (ASTM F2170)

   Drill hole to 40% of slab depth. Insert RH probe. Wait 72 hours for equilibrium. Read relative humidity.

   Pass: < 75% RH for most epoxies\nPass: < 80% RH for moisture-mitigating primers\nFail: > 80% RH — moisture barrier required

5. 5

   Document and Decide

   Record all readings with location map. If pass: proceed with grinding/coating. If fail: recommend moisture mitigation system or wait for slab to dry.

Tools Required