Concrete is one of the most common building materials used in new construction, particularly for flooring. The material constantly interacts with the environment around it, so influences such as temperature and humidity affect the moisture levels within it. Just as water is a vital ingredient when mixing concrete, excessive amounts of it can create numerous problems. The most common sources of excess moisture in concrete are free water—too much water in the concrete mixture—and moisture rising from below a slab. Because of the costly issues that may result from excess moisture in concrete construction, humidity control is an essential preventive and corrective measure.