Explain what ASTM F2659 electronic moisture meter readings can and cannot be used for when screening a floor slab or gypsum underlayment

Steps

1. Confirm ASTM F2659 is titled a 'Standard Guide for Preliminary Evaluation of Comparative Moisture Condition ... Using a Non-Destructive Electronic Moisture Meter,' applicable to concrete, gypsum cement, and other floor slabs/screeds
2. Explain the guide's own scope statement: it targets the top ~1 inch (25.4mm) of the slab/screed and is explicitly NOT intended to provide quantitative results as the basis for accepting a floor for moisture-sensitive flooring installation
3. Explain that the guide itself directs users to other ASTM test methods — F1869 (CaCl) and F2170 (in-situ RH probes) — for quantitative, spec-grade determinations on concrete slabs
4. Recommend using non-destructive meter scans as a triage tool — to identify wet spots or decide where to place a smaller number of quantitative RH probes or CaCl domes — rather than as the final accept/reject decision
5. Advise documenting both the screening meter readings and the follow-up quantitative test results together in the project moisture-testing record, since a dispute may later question why a screening-only method was relied upon