Which statement best describes the role of frost depth in footing design?

Which statement best describes the role of frost depth in footing design?

• A. It determines loads on the foundation.
• B. It dictates how deep the footing must extend to prevent movement due to freezing.
• C. It sets the required concrete strength.
• D. It controls the color of concrete.

Answer: (B)

Frost depth is the depth to which soil freezes in winter, and it drives potential frost movement of the ground. In footing design, the goal is to keep the footings below the zone that freezes so they rest in unfrozen soil and aren’t lifted by frost heave. That’s why the statement about frost depth determining how deep the footing must extend to prevent movement due to freezing is correct. The other choices mix in factors that come from different design concerns: loads on the foundation come from structural analysis, concrete strength comes from mix and design requirements, and color is an aesthetic property unrelated to frost effects.

Frost depth is the depth to which soil freezes in winter, and it drives potential frost movement of the ground. In footing design, the goal is to keep the footings below the zone that freezes so they rest in unfrozen soil and aren’t lifted by frost heave. That’s why the statement about frost depth determining how deep the footing must extend to prevent movement due to freezing is correct. The other choices mix in factors that come from different design concerns: loads on the foundation come from structural analysis, concrete strength comes from mix and design requirements, and color is an aesthetic property unrelated to frost effects.