A Standard for Testing the Dryness and Suitability of a Concrete Slab Intended to Receive Floor Coverings or Resinous Coatings Utilizing In-Situ Relative Humidity Test Equipment

This document does not purport to examine all of the concerns regarding concrete as a suitable substrate for the installation of floor covering and coating materials. The limitation of this section is to determine concrete in-situ relative humidity and surface pH levels for comparison to installation requirements of floor covering materials. Some manufacturers of flooring material and adhesives print a maximum tolerable level of in-situ relative humidity and most offer a range of pH for installations over concrete substrates. In-situ Relative Humidity and pH levels in excess of that tolerated by flooring systems specified must be corrected prior to flooring or coating application. The purpose of this specification standard is to insure testing is performed by qualified personnel and that the results of these tests are reported to the Owner, Architect and General Contractor, in writing, for review and/or corrective action.

The owner is best served by including these tests in section 01450. Thus having the tests performed by an outside agency, whose sole function is delivering accurate information. In the past this testing was often left out of construction documents or it may have been included in individual sections of Division 9. These tests were to be performed by the General Contractor or Flooring Contractor. This choice of specification location should be avoided as testing may be performed by untrained personnel or someone with a biased or conflicted interest.


Concrete In-Situ Relative Humidity and pH Testing (01450)


Part 1 – General

1.01 Section Includes

A. Provide in-situ concrete relative humidity and surface pH testing to all concrete specified to be covered with floor coverings or resinous coatings. Includes concrete placed below, on and above grade. (For re-model projects suspended slabs may be excluded from this requirement)

B. Testing shall take place after allowing concrete to dry for a minimum of 90 days. Testing to be scheduled no less than 1 nor more than 3 weeks prior to scheduled flooring installation.

1.02 Related Sections

A. Section 09620 - Specialty Flooring

B. Section 09640 - Wood Flooring

C. Section 09650 - Resilient Flooring

D. Section 09660 - Static Control Flooring

E. Section 09670 - Fluid Applied Flooring

F. Section 09680 – Carpet

1.03 References

A. ASTM F 2170-19a– Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using In-Situ Probes

B. ASTM F 710 – Standard Practice for Preparing Concrete Floors and Other Monolithic Floors to Receive Resilient Flooring.

1.04 Submittals

A. Report all test results in chart form listing test dates, time, depth of test well, in-situ temperature, relative humidity and pH levels.

  1. List test locations on chart and show same on 8 ½ x 11 site map (when such map is made available to testing agency)
  2. Deliver results in duplicate for distribution to Architect and General Contractor.

1.05 Quality Assurance

A. Independent Testing Agency

  1. Certified by Test Apparatus Manufacturer for product use.
  2. I.C.R.I. (International Concrete Repair Institute) certified, or other agency with verifiable experience

 B.  Digital Meter and Calibrated Humidity probes

          1. Minimum 2-point probe calibration

            C.  Wide range pH paper, and distilled or de-ionized water.

Part 2 – Products

2.01 - Manufacturers

A. Humidity and Temperature probe kit as manufactured by Vaisala, Tramex, Delmhorst, or equal.

B. pH test paper as manufactured by Micro Essential Laboratory, or equal.

Part 3 – Execution

3.01– Quantification of Relative Humidity at 40% of Concrete Thickness

A. The test site should be maintained at the same temperature and humidity conditions as those anticipated during normal occupancy. These temperature and humidity levels should be maintained for 48 hours prior and during test period. If meeting this criteria is not possible, then minimum conditions should be 75± 10° F and 50± 10% relative humidity. When a building is not under HVAC control, a recording hygrometer or data logger shall be in place recording ambient environmental conditions during the test period. A transcript of this information must be included with the test report.

B. The number of in-situ relative humidity test sites is determined by the square footage of the facility. The minimum number of tests to be placed is equal to 3 in the first 1,000 sq.ft. and 1 per each additional 1,000 square feet.

C. Determine the thickness of the concrete slab, typically from construction documents.

D. Utilizing a roto-hammer drill test holes to a depth equal to 40% of the concrete thickness*. i.e. 2" deep for a 5" thick slab, or 1 ½" deep for a 4" thick slab. Hole diameter shall not exceed outside diameter of the insertable test sleeve by more than 0.04". Drilling operation must be dry.

E. Wire brush and vacuum all concrete dust from test hole.

F. Insert a hole liner, or sleeve, to the full depth of test hole, assuring that the liner is capped or plugged at the end protruding from the concrete surface.

G. Permit the test site to acclimate, or equilibrate, for 24 hours prior to taking relative humidity readings.

H. Remove the sleeve plug and place a probe into the sleeve assuring that it reaches the bottom of the test hole. The test probe must be at temperature equilibration with the concrete slab (preferred method, allow sleeve and probe to equilibrate for 24 hours).

I. Read and record temperature and relative humidity at the test site.

* Elevated structural slab (not poured in pans) should be tested at a depth equal to 20% of its thickness.

3.02 Quantifying pH level (when requested or required)

A. At or near the relative humidity test site perform pH test.

1. Place several drops of water onto the concrete surface to form a puddle approximately 1" in diameter.

2. Allow the water to set for approximately 60 seconds

3. Dip the pH paper into the water and remove immediately, compare color to chart provided by paper supplier to determine pH reading

  B. Record and report results.

End of Section


For a more complete assessment of moisture content in the concrete, relative humidity profiling is encouraged. Rather than limiting testing to a single depth within the slab, profiling includes testing at depths of 20%, 40% and 60% of the concrete thickness. This extended testing may be limited to groupings in each 2,000 or 5,000 square feet, with single depth testing at each 1,000 square feet increment as outlined above.

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Revised 12/22