In the Flooring Industry, there are generally three acceptable procedures for measuring concrete subfloors for moisture.

1. The Relative Humidity Probe, ASTM F2170-11
2. The Calcium Chloride Test, ASTM F1869-10
3. Electronic non-destructive Impedance Meter ASTM F2659

Unfortunately, not all three types of the test methods listed above cross over into all the different categories of flooring. The test methods also measure concrete moisture in different ways and there is no way to cross over the results.

The Relative Humidity Probe is testing the internal Relative Humidity of the concrete slab. The probe must be in the concrete slab for 60 – 72 hours and will give you a percentage reading of the concrete moisture

The Calcium Chloride Test is measuring the moisture vapor emission of the top of the concrete slab. The Calcium Chloride test must run 60 – 72 hours and will give you a reading of pounds per 1000 square feet, per 24 hours.

The Electronic non-destructive Impedance Meter is measuring the resistance of the concrete slab. This test gives you an immediate reading. Generally a reading of 4 – 4.5 or lower on the Concrete Scale is acceptable method with some hardwood flooring manufacturers. The Tramex Concrete Moisture Encounter is one of the most used meters in this category.

Relative Humidity Probe

Calcium Chloride Test

Electronic Non-destructive Impedance Meter

There are other methods of moisture testing concrete slabs that are generally not acceptable.

• Poly Film Test. This is edge taping a 3′ x 3′ piece of plastic down on the concrete slab and checking to see if moisture appears under the plastic in 24 hours. This is no longer an accept- able test method for most flooring categories. However, Armstrong/Bruce hardwood still has this procedure listed as an acceptable test method in their engineered hardwood instructions.
• Apply 3′ x 3′ pieces of polyethylene film to the subfloor and leave in place for 24 hours. Assure all edges are completely sealed with water resistant tape. Darkened concrete or condensation on film indicates presence of moisture and requires additional measurements with the Tramex Meter, Calcium Chloride or RH test.
• Using a Pin Meter and pushing the pins hard against the concrete subfloor. I can usually tell when this method is done. The installer will generally have a low percentage type reading (5% – 20%) over a concrete subfloor.

Poly Film Test

Pin Meter

So what are the acceptable testing methods for the various types of flooring categories?

Commercial and Residential Vinyl Sheet, Tile, and LVT Flooring – The acceptable test methods for testing concrete slabs with the products listed is the Relative Humidity Probe ASTM F2170-11, and the Calcium Chloride Test ASTM F1869-10.

Rubber Flooring – The acceptable test methods for testing concrete slabs for Rubber Flooring is the Relative Humidity Probe ASTM F2170-11, and the Calcium Chloride Test ASTM F1869-10. Some manufacturers like NORA, specify that only Relative Humidity Probe ASTM F2170-11 be run and they also specify what probe must be used.

Laminate Flooring – The acceptable test methods for testing concrete slabs for Laminate Flooring is the Relative Humidity Probe ASTM F2170-11, and the Calcium Chloride Test ASTM F1869-10.

Hardwood Flooring – The acceptable test methods for testing concrete slabs with Hardwood Flooring is the Relative Humidity Probe ASTM F2170-11, and the Calcium Chloride Test ASTM F1869-10. Some manufacturers (Armstrong/Bruce/LM) will accept the use of the Electronic non-destructive Impedance Meter (Tramex Moisture Encounter). As stated above, Armstrong/Bruce accepts the Poly Film Test as well.

Cork Flooring – The acceptable test methods for testing concrete slabs with Cork Flooring is the Relative Humidity Probe ASTM F2170-11, and the Calcium Chloride Test ASTM F1869-10. Most manufacturers I researched only recognized the Calcium Chloride Test ASTM F1869-10.

Carpet – Per the Carpet and Rug Institute, the acceptable test methods for testing concrete slabs with Carpet is the Relative Humidity Probe ASTM F2170-11, and the Calcium Chloride Test ASTM F1869-10.

Please remember, when performing any moisture testing over concrete or wood subfloors, it is critical to document all your results. In the event the flooring should fail due to moisture, you now have a reference point to fall back on.

Special Thanks to JJ Haines for the info!