The moisture vapor emission rate (MVER) is the rate at which water (in a vapor form) emits from a concrete substrate. We measure the MVER using a calcium chloride moisture test over a fixed period of time. Test results are quantified in pounds per 1,000 square feet (e.g., 3 pounds).
The reason for measuring the MVER is to determine if (at the time of the test) the subfloor is suitable for the flooring product and the installation method being considered. NuBroadlok™ Premium Multi-Purpose Adhesive for Mohawk's broadloom carpets requires: "Calcium Chloride Moisture Test (ASTM F1869) results must not exceed 5.0 lbs." If the vapor emitted is too high (e.g., 13 pounds), an installation may fail or a flooring product may be ruined. A high MVER requires moisture remediation or a complete change in plans.
The Tampa Bay region, especially in our flood zones, can have unacceptably high moisture emission rates. Current weather conditions can influence the current MVER. To illustrate, the rainy season during our summer months can temporarily elevate a MVER due to increased ground saturation and an increasingly pressurized Floridan aquifer. Additionally, changes in the building's ambient humidity and temperature will influence the MVER, so maintaining a normalized HVAC setting is important.
An alternative concrete moisture test to the MVER is a relative humidity (RH) test. The MVER is expressed in pounds while the RH is expressed as a percentage.
Wolfe Flooring provides both concrete moisture testing methods.