The calcium chloride moisture test is a testing method to quantify the moisture vapor emission rate (MVER) of a concrete slab. The calcium chloride moisture test, when following ASTM F1869, has been a widely accepted moisture test for decades. Although subject to imperfection, the calcium chloride moisture test is one of the most accurate means by which to measure the MVER.
Calcium chloride testing kits use anhydrous calcium chloride. (Anhydrous means free of moisture.) The calcium chloride powder is weighed before and after the test to determine how much moisture vapor was absorbed during a period of time. Prior to testing, the concrete slab needs to be cleaned and free of residue in a 20-inch by 20-inch site. Proper testing requires three (3) testing kits in the first 1,000 square feet. An additional testing kit is added for each additional 1,000 square feet.
The calcium chloride moisture test gives current conditions and does not indicated future conditions because concrete's MVER is influenced by the air's current relative humidity and the ground's current moisture vapor. The HVAC system must be operating at normal conditions of temperature and humidity at the time of testing and for a period of no less than 48 hours prior to testing. If the building has been without climate control (e.g., new construction), prior to testing, the building envelope should be sealed and the HVAC system should operate at normal conditions for a period of two or more weeks. These tests require multiple site visits over several days. To enhance documentation, we can send the testing kits off for third-party, written verification.
Moisture is more likely a risk if the substrate is below grade, but on grade and above grade substrates can also have moisture problems. The State of Florida sits at low elevation, especially near our seashores. Moisture concerns are compounded by the fact that our entire state is situated atop the Floridan aquifer. Our groundwater remains under constant, upward pressure. Further, moisture vapor is a constant risk and must be considered when selecting and installing a flooring product.
Wolfe Flooring provides both the calcium chloride moisture test and the in situ probe test.