What is the minimum depth of a footing required to be below?

The minimum depth of a footing is required to be below the frost line to prevent damage caused by frost heave. When the temperature drops, moisture in the soil can freeze, leading to expansion. If footings are not placed below the frost line, the freeze-thaw cycles can push the foundation upward, causing settling and potential structural damage.

The frost line varies depending on geographical location, with colder climates typically requiring deeper footings. In contrast, while groundwater level, bedrock, and soil layer considerations are important in foundation design, they do not specifically dictate that footings must be placed at a minimum depth for the purpose of protecting against frost heave. Thus, the frost line is the most critical point concerning footing depth in relation to freezing conditions.