What is hygroscopic moisture?

Hygroscopic moisture refers specifically to moisture that is absorbed by materials from the air. This process occurs when materials take in water vapor, resulting in the material becoming damp. Common hygroscopic materials include wood, concrete, and certain types of insulation. These substances have the ability to attract and hold moisture due to their chemical structure and porosity.

Understanding hygroscopic moisture is crucial in moisture control practices, as it can affect the performance of building materials and contribute to issues such as mold growth, structural damage, or reduced insulation effectiveness. Recognizing how humidity in the environment interacts with materials helps in assessing potential moisture-related problems in buildings.

While other options mention different sources of moisture, they do not pertain to the specific definition of hygroscopic moisture. Ground moisture, condensation, and liquid seepage are all different forms of moisture issues and do not involve the absorption of moisture directly from the air by materials.