What Is Bulk Zoning?
Bulk zoning regulations restrict the density in a given area through a variety of building-specific measures, including floor-area-ratios (FAR), setback requirements, and open space requirements. Such provisions are separate from use-based zoning regulations, which restrict the type of use permitted in a given area, such as residential, industrial, or commercial.
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History
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In 1916, New York passed the nation's first comprehensive zoning resolution. This was largely in response to the construction, a year earlier, of the 42-story Equitable building. According to the New York City Department of City Planning, the Equitable building was designed to maximize floor area on the downtown, highly valuable lot, but the massive structure blocked out the sun and air from the streets below. The 1916 ordinance therefore imposed setback requirements. Instead of simply setting maximum building heights, the law provided for a "zoning envelope," which was a formula used to determine the placement of necessary setbacks. Setbacks were to follow a line drawn at a fixed angle from the street as a building rose in height. This ensured that some amount of sunlight would reach the streets.
Floor Area Ratio (FAR)
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FAR refers to the ratio of built floor area in a building to the size of the lot on which it stands. This is a common method for controlling density of commercial uses, such as office and retail properties. Suppose a vacant lot is 10,000 square feet and the maximum permitted FAR in the district is 4.0. This means that development on that lot may have, at most, 40,000 square feet of floor area (including all stories).
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Dwelling Units per Acre
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In a residential context, density is typically regulated by a maximum number of dwelling units per acre. A developer who owns 10 vacant acres, zoned for 2.0 dwelling units per acre, may subdivide the property into 20 separate homes.
Setbacks
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Setbacks help ensure that sunlight from above reaches the street below. A setback refers to that portion of a building that is set back from the base height of the building. Zoning ordinances achieve this effect through the enforcement of sky exposure planes, which are hypothetical lines drawn from the street level, or from a specified heigh about street level, to the top of the subject building. These setback requirements contribute to the "staircase" appearance of some buildings' profiles.
Open Space and Lot Coverage Ratios
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These approaches ensure that a minimum portion of a given lot is left open to the sky or that a maximum portion of the lot is built upon. Consider a vacant lot of 10,000 square feet with an open space requirement of 20 percent. This means that 2,000 square feet of the property must be left open to the sky. This is similar to a maximum lot coverage ratio of 80 percent; only 8,000 square feet of the lot may be covered by the building's footprint.
Yard Requirements
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These are open space requirements particular to the front, rear, or side lot lines of a particular parcel. No structure is permitted in these areas. This ensures the presence of adequate light and air between buildings on separate lots.
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References
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