1. In-situ RH probes (ASTM F2170) — best for concrete slabs; measures internal relative humidity.
2. Calcium-chloride MVER (ASTM F1869) — measures moisture vapor emission rate from the slab surface (useful for adhesives/finish acceptance).
3. Moisture meters (pin and pinless) — quick scans for wood, plywood, gypsum, and to locate “hot” spots before confirmatory testing.

Step-by-step: how to test a concrete floor (recommended order)

1. Start with a visual inspection & record conditions
   • Look for staining, efflorescence, paint failure, mold, buckling or wet pockets; note recent weather, HVAC status, and if slab recently poured. Take dated photos.
2. Run a quick non-destructive sweep with a pinless meter
   • Use a pinless (surface) meter to find areas of elevated moisture so you know where to place the more involved tests. Pinless is fast and non-invasive; pin meters give deeper/percent-MC style readings in some materials.
3. Perform ASTM F2170 in-situ RH (recommended for installation acceptance)
   • Install RH probe sleeves to the depth required (commonly 40% of slab thickness if drying from the top only; 20% if drying from both sides). Allow equilibrium time per the standard (manufacturers/standard specify typical equilibration times). ASTM F2170 is the reference test for long-term moisture condition inside the slab.
   • How many probes? 3 probes for the first 1,000 ft², plus at least 1 additional probe per additional 1,000 ft² (report location of each probe).
4. (Optional / older method) Calcium-chloride MVER — ASTM F1869
   • Place test kit per ASTM F1869 and measure moisture vapor emission in lb/1000 ft²/24 hr. Use this when the installer or product specification still requires MVER. It measures surface vapor emission only (top ~¾”).
5. Document & compare to flooring manufacturer limits
   • Many finish systems accept MVER ≤ 3 or 5 lb/1000 ft²/24 hr or RH ≤ a given % (some products accept up to 75% RH — check the product TDS). Always confirm the flooring/adhesive manufacturer’s acceptance criteria before installing. (Example: Laticrete TDS shows a max 5 lb/1000 ft² or 75% RH for certain systems.)

How to test wood subfloors / wood flooring

1. Use a pin-type moisture meter (or calibrated pinless if manufacturer allows) to get percent moisture content (MC) for wood. Measure at many points (dozens across the job) and average.
2. Check the moisture differential: typical guidance is that hardwood should be acclimated and the difference between wood flooring MC and the subfloor (or framing) should be small — commonly cited tolerances are about 2–4% difference and typical target MC for wood flooring often in the 6–9% range (regional variation applies). Always follow the wood manufacturer’s spec.
3. Oven-dry lab test (for absolute moisture content on small samples) — use if you need an exact mc% benchmark for disputes.

Other useful methods (advanced / investigative)

• Infrared thermal imaging (IRT) — great for locating hidden moisture patterns and mapping wet areas (useful before discrete tests). Works best when there’s a thermal contrast or when used with stimulated cooling/heating.
• Ground-penetrating radar (GPR) / combined techniques — used for complex diagnostics (roofs, thick slabs).

Practical guidance: how many test points & where

• For concrete RH testing: ASTM F2170 → 3 probes for first 1,000 ft², +1 per additional 1,000 ft²; at least one probe within 3 ft of exterior walls is usually required. Mark probe positions on a plan and photo them.
• For wood/plywood roof or subfloor: take multiple moisture meter readings — common rule: 20 readings per 1,000 ft² (or follow installer guidance) so averages are representative.

Common acceptance thresholds (common industry guidance — always confirm with the product manufacturer)

• Calcium chloride (ASTM F1869 / MVER): many installers accept ≤ 3 lb/1000 ft²/24 hr for sensitive products; some systems accept up to 5 lb/1000 ft²/24 hr (check product TDS).
• In-situ RH (ASTM F2170): some manufacturers accept up to 75% RH; many wood/Vinyl/adhesive specs set lower limits — confirm with the flooring maker.
• Wood flooring moisture content: target typically 6–9% (region dependent); keep wood-to-subfloor difference within 2–4%.

Important: these are examples — the flooring manufacturer’s technical data sheet (TDS) controls. If the TDS says different numbers, follow the TDS.

What to record (data checklist)

• Project, address, date/time, tester name and tool serial numbers
• Weather/HVAC status during test (temp & RH)
• Test method (ASTM F2170 or F1869 or moisture meter), exact locations (sketch/photo), depth of probes, and raw readings (RH%, MVER lb/1000 ft²/24 hr, wood %MC) — save photos of each location.

When to call a pro / hire testing lab

• If RH or MVER values are near or above manufacturer limits.
• If moisture is non-uniform (pockets of high moisture).
• If you need an ASTM-compliant report for warranty, insurance, or contractual acceptance. Certified testers provide reports that document compliance.

Quick field checklist (copy/paste)

1. Visual inspection + photos (date/time).
2. Quick pinless sweep (map hot spots).
3. Mark probe locations per ASTM F2170 (3 per 1,000 ft², +1 per extra 1,000 ft²).
4. Drill sleeves, insert RH probes, allow equilibration per ASTM F2170, record RH & temp.
5. (Optional) Run ASTM F1869 calcium-chloride in occupied/contractor-required areas.
6. For wood, take multiple pin readings and confirm wood MC vs subfloor (target per manufacturer).
7. Save report + recommend remediation or acceptance based on manufacturer limits.