Frost Line

The frost line—also known as frost depth or freezing depth—is most commonly the depth to which the groundwater in soil is expected to freeze. The frost depth depends on the climatic conditions of an area, the heat transfer properties of the soil and adjacent materials, and on nearby heat sources. Many Minnesota and Illinois customers, historically, have had frost line requirements for fence and gate barriers. This requires them to order longer posts (for in-ground applications) than the minimum length(s) promulgated on the Post Charts page on this website.