North Carolina Building Contractor License Practice Exam

What is the required minimum depth for footings below the undisturbed ground surface?

1. 12 inches

2. 24 inches

3. 6 inches

4. 18 inches

The correct answer is: 12 inches

The requirement for footing depth is critical to the overall stability and integrity of a structure. Footings provide a stable base to support the weight of the building and transfer loads to the underlying soil. In general, the minimum depth of footings is determined by local building codes, soil conditions, and frost line considerations. In many jurisdictions, including North Carolina, the minimum depth for footings is typically established at 12 inches below the undisturbed ground surface. This depth helps to ensure that footings are placed below potential frost levels, which can cause soil expansion and contraction, leading to instability. By establishing footings at this minimum depth, builders can minimize risks related to soil movement and ensure the durability and safety of the structure. The other listed depths either fall short of the necessary requirements for stability or exceed typical requirements based on standard building practices in many regions. Establishing footings deeper than necessary can lead to unnecessary costs and labor without a corresponding benefit for most structures. Understanding the significance of the proper footing depth is essential for construction practices and compliance with relevant building codes.