Footings should extend to a minimum depth of 12 inches below previously undisturbed soil. Footings also must extend at least 12 inches below the frost line (the depth to which the ground freezes in winter) or must be frost-protected.
Footings and Foundations How Deep?
Footings and foundations are the most important part of any building structure and the depth at which they are set will depend on a variety of factors.
Generally, the deeper the footings and foundations, the more stable the building will be. When building a structure, the footings and foundations are the section of the structure that bear the most weight, so it is important to ensure that they are deep enough for the structure to be stable.
The depth at which footings and foundations must be set is determined by the soil type and the weight of the structure that is being built.
For buildings that are built in sandy or loamy soils, the footings and foundations should be at least two feet deep. For buildings built in clay soils, a minimum depth of four feet is recommended.
The weight of the structure will also determine how deep the footings and foundations must be set. For buildings made of concrete, the minimum depth should be six feet, while for buildings made of wood, the minimum depth should be four feet.
When setting footings and foundations, it is also important to consider the frost line. Depending on where the building is being built, the frost line can be anywhere from eight inches to four feet deep. This is due to the fact that