Footings shall be stepped under which condition?

• A. if the ground surface slopes more than one unit vertical to ten units horizontal or where necessary to change the top footing surface elevation
• B. when soils are unstable
• C. on every new foundation
• D. only when building height exceeds a certain threshold

Answer: (A)

Footings are designed to distribute the weight of a structure over a larger area, and stepping them is a technique used to adjust for sloped ground conditions. The correct choice indicates that footings shall be stepped when the ground surface has a significant slope, specifically more than one unit vertical to ten units horizontal. This ensures that the footing can adequately support the structure by adapting to the slope and maintaining a stable base.

When footings are stepped under these conditions, it helps in preventing potential issues such as uneven settling or structural instability, which could arise if the footing were to remain level on a sloped site. This method facilitates proper weight distribution and enhances the overall integrity of the foundation.

The other conditions presented, such as unstable soils, having footings on every new foundation, or a requirement based solely on building height, do not universally necessitate stepping footings. Each of these situations requires different considerations related to foundation design, but they do not specifically address the need for stepping due to sloped ground surfaces. Therefore, the emphasis on stepping footings for sloped conditions is an essential practice in ensuring structural safety and effectiveness.