A frost wall, also known as a foundation wall, extends below the frost line and helps prevent frost heaving. Frost heaving occurs when water in the soil freezes and expands, pushing up on the foundation and potentially causing damage. Frost walls are typically made of concrete and extend at least 4 feet below the frost line to protect the foundation from frost and water infiltration. They are often insulated to further reduce the risk of frost damage. Frost wall design and construction must comply with building codes and industry standards to ensure adequate frost protection and structural integrity.