Structural Perspective 1

Frost Depth

Winter is upon us. The majority of the county is currently experiencing or has experienced dangerous freezing conditions. Frozen ground can have a devastating impact on your structure’s foundation if you are above the frost line. Frost Depth varies by geographic location, and frost heave is caused when ice forms in the soil during the freezing process. This ice can cause your foundation to temporary rise, or permanently settle as the ground freezes from the top and penetrates downward. 

Ingredients for frost heave:

• Cold Weather: Below freezing temperatures

• Presence of Water: Moist soil or high water table

• Fine Soil: Silty and Clayey soils that allow permeability

Foundation below Frost Depth prevents Frost heave Frost Heave can cause the Foundation to rise, then settle when the ice melts

Photo Cred: Fine Homebuilding, Drawings: Christopher Mills.

Fun fact: The soil/underwater sediment that remains frozen in Alaska is called permafrost, and special provisions is taken when designing a structure’s foundation to avoid heat from the structure melting the permafrost.