A spread footing foundation, which is typical in residential building, has a wider bottom portion than the load-bearing foundation walls it supports. This wider part "spreads" the weight of the structure over more area for greater stability.
These foundations are common in residential construction that includes a basement, and in many commercial structures.
But for high rise buildings they are not sufficient.
A spread footing which changes elevation in several places in a series of vertical "steps" in order to follow the contours of a sloping site or accommodate changes in soil strata, is termed a stepped footing.
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