How to Write A Good Concrete Moisture Testing Specification
The best way for the owner to assure that the testing gets done is to write a testing specification themselves. A simple statement such as “install floor covering according to manufacturer’s instructions” is not enough. What is needed is to create a specification section regarding moisture testing that shall 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 the copy of the test report.
Type of testing to be done
ASTM F 1869 moisture test
ASTM F 2170 moisture test
Add pH testing per ASTM F 710 if indicated.
Number of tests
The standard calls for three tests for the first 1,000 sq feet and one test for each 1,000 sq feet thereafter. However, this number may change, depending on the size of the slab, age of concrete, building temperature and RH, and the preliminary results from the Static Moisture Testing (Internal Test).
Timing of testing
The temperature and humidity conditions are important for the dynamic test (Calcium Chloride). For new construction, dynamic testing should be done after the building is enclosed and the HVAC system is running, and the areas have reached steady state conditions. For a renovation project, if time permits, it is recommended that the testing be done at least a month prior to the scheduled flooring installation, so there is adequate time for corrective measures to be taken if they are necessary.
Test reports should contain the conditions at the time of testing, methodology of testing and test results. This is an important way to document not only the test results but the accuracy of the testing that was done. The specification should also identify who is to receive the report – the owner, general contractor, architect or all parties.
The more sophisticated reporting done will show a floorplan with the test results, which can help the construction team identify problem areas in the floor.
The report should include options for repairing a floor that exceeds the manufacturer’s limits.
The moisture testing specification may be standalone specification as part of a concrete floor slab section that details some of the key points of a concrete industry standard designed to prevent floor covering moisture problems.
The details may include the need for:
- The concrete to be dry, clean, smooth, and free of contamination.
- Concrete should be moist cured for at least seven days (failure to do so may increase permeability four times or more)
- The installation of a vapor retarder directly under slabs on or below grade.
- The use of moisture-retaining coverings for curing concrete.
NOTE: Restricting water/cement ratio to 0.40 in combination with a 7 day moist cure can result in concrete able to effectively restrict moisture movement and reduce vapor emissions.
Moisture problems can be solved through expensive moisture remediation processes;
However, the best method is prevention!