Choose between ASTM F2170 in-situ RH probes and ASTM F1869 calcium chloride testing for pre-flooring-installation slab moisture

Steps

1. Confirm which test method the flooring/adhesive manufacturer's warranty requires before testing -- many manufacturers now require or prefer F2170 relative-humidity results over F1869 for warranty compliance.
2. For ASTM F2170, drill test holes to the depth fraction of slab thickness specified in the standard for the slab's drying condition (one-side vs. two-side drying), seal the probes, and allow the manufacturer- or standard-specified equilibration period before reading.
3. For ASTM F1869, use the surface-mounted calcium chloride kit per the standard's conditioning and exposure duration, and recognize it measures near-surface moisture vapor emission rate rather than internal slab relative humidity.
4. Take at least the minimum number of test locations required by the contract/manufacturer (commonly scaled by floor area) and document ambient temperature and humidity during testing.
5. Re-test after any relevant condition change (HVAC turned on, additional curing time) rather than relying on a single early reading, especially on thick or one-side-drying slabs.