Concrete Moisture Testing

Too often a decision to install floor coverings or coatings is based on poor information or the simple demand to meet a schedule. If a concrete substrate has a moisture vapor emission level, in-situ relative humidity or a pH level in excess of that which can be tolerated by the flooring material, the losses are rarely limited to the flooring itself. The occupant may end up, at best, with an eyesore, at worst there may be a trip or slip and fall hazard with dire financial consequences. The need to vacate a floor after move-in, while repairs are made, can be extremely costly.

Statewide Inspection offers moisture testing in accordance with ASTM F2170 “Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes” This test method has been used in Europe for many years and has been proven to be more accurate than the calcium chloride test currently used. Proper moisture levels are critical with the new generation of solvent free adhesives, as they are more susceptible to failure at lower moisture levels.

Scientific testing shows that ASTM F 1869 (the calcium chloride test) only measures vapor emission from the top one inch or so of the concrete slab. Since most concrete slabs dry from the top down, this may not measure moisture down below. This explains why a floor can test “dry” with an F 1869 test and then become “wet” again after the floor is installed. F 1869 tests give a “snapshot” of the moisture condition, while F 2170 RH tests can monitor trends and indicate the rate of drying, allowing us to predict when a floor will be dry enough for installation.

In situ Rh- ASTM F2170

  • ½” diameter Rh sleeve is drilled into concrete and capped
  • The test involves a three-day waiting period, but only the first time.
  • Once the sleeve is placed and capped, readings can be taken at any time.
  • Because the sleeve is in the concrete there is ittle or no risk of compromising the test site.
  • Rh can be monitored using the original kits for an indefinite period of time.

Calcium Chloride- ASTM F1869

  • The calcium chloride test takes four days to run: grind the slab, wait one day.
  • Day 2- Weigh and place the kit, wait three days.
  • Day 4- Pick up kit, weigh and calculate.
  • High profile domes-subject to compromise and inaccurate results.
  • To repeat a test in the same spot, it’s another 3-day test
  • High profile domes-subject to compromise and inaccurate results.
  • To repeat a test in the same spot, it’s another 3-day test

Linda Lockwood
Certified Flooring Inspector
Statewide Floor Covering Inspection Service


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