Under what condition must footings be stepped according to code?

Footings must be stepped when the ground surface slopes more than one unit vertical to ten units horizontal because this type of slope creates conditions where standard footing dimensions would not provide adequate support. Stepping the footings helps to distribute the structural load more evenly and provides stability as the foundation adjusts to the changing topography. This practice is particularly important in sloped areas to prevent settling or shifting that could compromise the integrity of the structure.

The other conditions mentioned do not meet the specific requirements set by the building code. Aesthetics do not dictate structural needs; flat surfaces typically do not require stepped footings as they can adequately support walls with uniform footing dimensions; and areas with high seismic activity may have separate guidelines, but they do not inherently require stepped footings unless the slope condition is also present.