The Frost Line

The frost line is the depth underground where temperatures stay consistently cold enough for water to freeze. During winter, the surface may freeze, but closer to the surface, the ground remains warm enough to prevent ice formation. The frost line varies depending on climate, typically a few feet deep in temperate regions and much deeper in colder areas. This concept is important for construction, as foundations need to be below the frost line to prevent shifting or damage caused by freeze-thaw cycles. Essentially, it marks the boundary between frozen and unfrozen soil underground.