These are two methods for checking for moisture vapor in concrete floors. One of the methods is a quantifiable scientific test. The other is a quick and easy alternative for the DIY person. The former determines the rate of moisture vapor transmission (MVT) or Moisture Vapor Emission Rate (MVER). It is important to measure this for environmental and safety concerns. It is also important for all floor coverings which are susceptible to failure from excessive MVT or MVER.
Scientific Method for Calculating Moisture Vapor in Concrete Floors
The calculation of MVT is scientifically determined using the standard ASTM F-1869 which is available here. Basically, the test employs a calcium chloride test kit which measures the amount of moisture emitted. This calculates pounds of water per 1,000 square feet of concrete in a 24 hour test period (or Kgs/100m2/24 hr). If the result of the test is greater than 3lbs the MVT or MVER is considered too high depending on the desired floor covering. If the flooring material is rubber, solid vinyl or wood, the manufacturer usually requires a maximum of 3 lbs. On the other hand for a vinyl composition tile a test result of less than 5lbs may be acceptable. However, you should always consult the manufacturer of the flooring for specific moisture level requirements.
DIY Test Method
The easier test employs the standard ASTM D-4263 is available here. Basically, tape an 18″ x18″ square of polythene to the surface of the concrete for 24 hours. If moisture is present on the underside then the MVT is considered to be too high. There is a way to quantify this method, but for the DIY person this will indicate if there is a problem. It will show if there is likely to be a failure of flooring or topical coatings on the concrete due to poor adhesion.