If a subfloor is too wet to install a flooring material, it needs to be dried. If you proceed with the installation, you will be held accountable for that decision. So what do you do?

Many problems occurring from moisture are blamed on the floor covering industry. The fact of the matter is that the moisture condition is not floor covering problem, it is a concrete problem. If there is a solution, it must take place either when the concrete is specified or when it is poured.

How do you conduct a Moisture Test?

The first step is to understand the laws of moisture migration: moisture always migrates from a cool environment to a warm environment, from a wet environment to a dry environment, and moisture travels as a heavily moisture-laden gas vapor.

The constants are as follows:

The temperature on the job site at the time of the moisture test should be comparable to the temperature at the time the floor covering is to be installed (60-70 degrees F). Never conduct a moisture test with temporary heating or cooling.

Humidity on the job site must be stabilized to normal conditions. High humidity produces minimal moisture migration; low humidity promotes increased moisture migration.

The concrete must be clean and free of all types of sealers, curing compounds or anything that can serve as a vapor barrier to the test area. It is a good idea to abrade the area being tested to ensure that the floor is in a good, porous condition. Sealers and curing compounds retard moisture migration.

The time required to do a test will vary according to type, so be sure you know the limitations of each type of test used. Remember that nothing of any consequence happens within the first 48 hours when doing mat, bond or calcium chloride tests.
Know the types of tests available.

Moisture conditions for concrete fall into two categories: Static and Dynamic. A Static moisture condition is a function that determines how wet the internal structure of the concrete is at present. A dynamic moisture condition is a function of how much of the moisture in the concrete is currently migrating from the surface.

Moisture testing for concrete also falls into two categories: Subjective and Objective. A subjective moisture test relies upon the person testing to decide whether or not it is safe to install the floor covering. An objective moisture test qualifies the moisture condition in terms of percentage or pounds of emissions.