Concrete: Moisture Testing - January 2010

By Lee Eliseian

One of the most common problems in commercial floorcovering continues to be floorcovering failures related to excessive moisture and pH of concrete floor slabs, and all flooring categories are affected. Among other problems, moisture and high pH can cause adhesive to ooze and PVC flooring to debond. There can be a loss of holding strength because of re-emulsified adhesive under carpet tile.

In 2001, a number of industry associations and organizations within the floorcovering industry endorsed a white paper position statement on concrete slab moisture testing. It states that many concrete slab moisture related flooring problems can be attributed to the advent of rapid changes within the construction industry such as:
• The loss of asbestos in resilient flooring.
• The loss of solvents from adhesive and coating.
• Increased use of water for easier concrete placement.
• Absorptive aggregate in lightweight concrete.
• Fast track construction schedules.

In the increasingly complex world of construction—with growing environmental requirements, technological changes in formulations, and advances in measuring and testing concrete—providing optimum substrate conditions requires greater knowledge and more stringent attention than ever. In addition, innovative products, installation methods/materials and environmental regulations have created a more complex environment in which floorcoverings are installed.

Many unforeseen problems have surfaced that have led to unnecessary disputes, increasing confusion and lawsuits. In an effort to reverse this trend, a more science-based approach was needed to clearly identify why moisture-related flooring failures occur, with reasonable expectations for those responsible for moisture testing. The industry recommends that concrete slab moisture testing be performed by qualified independent third-party agencies.

Proper Moisture Testing
Specify proper moisture testing right from the start to reduce the risk of concrete slab moisture and pH related flooring problems. Proper testing before installing a new floor or replacing an existing floor is the only way of knowing the moisture condition of the concrete, rather than guessing what it might be. You can’t see, smell or feel moisture within or emitting from a concrete slab so the only way to really know is quantitative testing.

Test if it’s old or new concrete, even if the existing flooring looks to be in good shape.

The industry standard, ASTM F 710, Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring, puts it quite simply, and all floorcovering and adhesive manufacturers agree: “All concrete slabs shall be tested for moisture regardless of age or grade level.” On-grade, above-grade, below-grade, the slab should be tested.

There are two quantitative testing methods widely recognized in the industry, and they are referenced in ASTM F 710. Both testing methods provide valuable information and it’s a good idea to perform both of them in addition to the pH test. Usually these three tests are done at the same time, and the data collected will provide a relevant understanding of the existing concrete slab’s moisture condition.

ASTM Industry Standards
The importance of proper specifications cannot be over emphasized. The volunteers from the floorcovering and concrete industries who have worked together to create the ASTM documents have done a great service to all in the floorcovering community by creating industry standards. These documents, created through a consensus process, are “the book” on how things need to be done.

In addition, the floorcovering and adhesive manufacturers have created published guidelines that follow these standards, often quoting them directly. Failure to follow a manufacturer’s guidelines usually voids the warranty and in the event of flooring problems, a great deal of finger pointing can occur, which does not solve the problem and can create ill will among the parties involved.

Specifications
There is much concern about whose responsibility it is to test the floor. The Floor Covering Industry White Paper Position Statement on Moisture Emission Testing recommends independent third-party testing rather than assuming the contractor, landlord or developer will do the right thing and test the floor.

The best way for the owner or tenant to assure that comprehensive moisture testing gets done is to write a testing specification themselves. A simple statement such as “install floorcovering according to manufacturer’s instructions” is not enough. What is needed is to create a specification section regarding moisture testing that will leave no question about what testing is to be done, when the floor will be tested, who is to do the testing, how the results are to be reported, and who will receive a copy of the test report.

Depending on the circumstances, an analysis of the test results may also be commissioned. This would require the testing agency’s consultants to compare the test results with the requirements of the floorcovering and adhesive manufacturer and make an assessment as to the suitability of the concrete slab for the particular floorcovering product that has been specified. If the concrete is not in compliance, corrective measures may need to be taken prior to the floorcovering installation.

How a moisture testing specification is written and used may vary, depending on the type of project. In the case of renovation or flooring replacement projects where the owner is directly controlling the scope of work, the document may be more of an internal guideline.

In either case, it is important to specify who is responsible for testing and who is responsible for conducting the testing.

Some Specification Elements
The moisture testing specification should detail key points of ASTM industry standards designed to prevent floorcovering moisture problems. ASTM F 710 covers many of these points and is an important document for owners to have in their specification libraries.

The ASTM standard calls for three tests for the first 1,000 square feet and one test for each 1,000 square feet thereafter, but the owner may change the number of tests based on their needs.

The temperature and humidity conditions are important on new construction, and testing should be done after the building is enclosed and the HVAC system is up and running. For a renovation project, the testing should be done at least a month prior to the scheduled floorcovering installation, so there is adequate time for corrective measures to be taken.

Test reports should contain as much information as possible about the conditions at the time of testing, methodology of testing and test results. This is an important way of documenting not only the test results but the accuracy of the testing that was done. A simple list of test results alone is not acceptable. The specification should also identify who is to receive the report—the owner, general contractor, flooring contractor, architect, or all parties. More sophisticated reporting will show the test results on a map of the facility.

The report may also include options for repairing a floor that exceeds the flooring/adhesive manufacturer’s recommended limits.

Related Topics:Coverings, Lumber Liquidators

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