Projects

Service: Concrete Floor Slab Moisture Testing
Facility Type: Bank Branch

Description:

The purpose for performing this testing was to quantify the existing moisture content in the concrete floor slab. In addition, the testing was also to attempt to identify the source of moisture affecting installed floor materials. Potential sources of moisture would be earth borne moisture passing through the concrete slab, or surface originated moisture, from improper or excessive rug shampooing or other cleaning activities.

During the investigation, ACC performed the following tasks: 1) conducted relative humidity (RH) testing in the concrete floor slab using in-situ probes, and 2) collected electrical impedance and pH readings from the exposed concrete slab.

The concrete floor slab moisture testing resulted in the following conclusions:

• Concrete in-situ RH readings collected from the subject area were above 85% RH, ranging from 90% RH to 97% RH. The RH values were near equilibrium through the slab thickness. The concrete floor slab in these testing areas was covered with either glued-down PVC-backed carpet tiles or vinyl floor tiles.
• Concrete in-situ RH readings collected from the Teller Work Area were below 85% RH, including 75% at 1.6” in depth, 77% at 2.0” in depth, and 83% at 3.0” in depth. The concrete floor slab in the Teller Work Area was covered with glued-down broadloom carpeting.
• All electrical impedance meter (MC) readings were above 4.5%, ranging from 4.6% to 6.9%.
• Concrete surface pH levels in the Teller Work Area were 8.23, or within the acceptable range of >5.0 to 5.0 to <9.0, ranging from 9.67 to 11.80.

Based on the findings of the concrete floor slab moisture testing, ACC makes the following recommendation(s):

• With the exception of the Teller Work Area, the levels of moisture reported from the in-situ RH testing, at all other test locations, exceed the limits of acceptability set by flooring, coating and adhesive manufactures. The floor concrete slab will not permit the successful installation of directly adhered, moisture sensitive, floor coverings or coatings without the introduction of a moisture vapor emission control system. If a sealer is installed, ensure the product is warranted to control in-situ RH of no less than 100% and/or no less than 20 lbs. of vapor emission.