Building setback

A setback, sometimes called step-back, is a step-like recession in a wall. Setbacks were initially used for structural reasons, but now are often mandated by land use codes, or are used for aesthetical reasons. In densely built-up areas, setbacks also help get more daylight and fresh air to the street level.

Setbacks were used by ancient builders to increase the height of masonry structures by distributing gravity loads produced by the building material such as clay, stone, or brick. This was achieved by regularly reducing the footprint of each level located successively farther from the ground. Setbacks also allowed the natural erosion to occur without compromising the structural integrity of the building. The most graphic example of a setback technique is the step pyramids of Mesopotamia and Ancient Egypt, such as the Teppe Sialk ziggurat or the Pyramid of Djoser.

For centuries, setbacks were a structural necessity for virtually all multi-level load-bearing masonry buildings and structures. As architects learned how to turn setbacks into an architectural feature, most setbacks were however less pronounced than in step pyramids and often skillfully masked by rich ornamentation.

The introduction of a steel frame structural system in the late 19th century eliminated the need for structural setbacks. The use of a frame building technology combined with conveniences such as elevators and motorized water pumps influenced the physical growth and density of buildings in large cities. Driven by the desire to maximize the usable floor area, some developers avoided the use of setbacks, creating in many instances a range of fire safety and health hazards. Thus, the 38-storyEquitable Building, constructed in New York in 1915, produced a huge shadow, said to "cast a noonday shadow four blocks long" which effectively deprived neighboring properties of sunlight. It resulted in the 1916 Zoning Resolution, which gave New York City's skyscrapers their typical setbacks and soaring designs.

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