Guides / Decision guide
Test the slab before choosing a floor
Why moisture testing of a concrete slab comes before product choice, which test methods exist, and who sets the pass limits.
What is not established
- No moisture result, pass limit or test method is established for any slab or product.
- Only the public ASTM abstracts were read.
- This guide is not an installation specification.
Two recognized test methods
- ASTM F2170 measures relative humidity inside the slab with in-place probes. ASTM's abstract notes that flooring manufacturers generally require moisture testing before installation and that results reflect only the tested locations and time.
- ASTM F1869 measures the moisture vapor emission rate from bare concrete with anhydrous calcium chloride, to judge suitability for resilient flooring. Results describe conditions at the time of testing only.
Who sets the pass limit
Neither method sets an acceptable value. The flooring or adhesive manufacturer does, in its installation instructions. Ask which method the chosen product requires and what result it accepts before the order is placed.
Wood over concrete
The National Wood Flooring Association's concrete subfloor fact sheet says wood floors can go over concrete when the slab is dry, flat within stated tolerances and free of contaminants, with moisture tests per the flooring and adhesive manufacturer's requirements, and strongly recommends a low-permeance vapor retarder.
A waterproof claim on a plank does not replace a slab test. The research found no official manufacturer family page that states a slab moisture limit, humidity range or Florida suitability; those sit in installation documents.
Original paraphrase of ASTM store abstracts and the NWFA fact sheet. Only the public abstracts were read; no pass values are given here.
Sources: ASTM F2170 relative humidity in concrete slabs; ASTM F1869 moisture vapor emission rate; NWFA concrete subfloors fact sheet
Sources
External references are provided for research context. A source link does not indicate enrollment, endorsement, or availability in your area.
- ASTM F2170 relative humidity in concrete slabs, accessed
- ASTM F1869 moisture vapor emission rate, accessed
- NWFA concrete subfloors fact sheet, accessed