Zoning and the Wedding Cake

Why Cities Go Up names five conditions of the vertical push: land, access, technology, rules and money. This reading is about rules, and the clearest example is New York.

The Equitable Building

Completed in 1915 at 120 Broadway, the Equitable Building rose about 40 stories straight up from its property lines with no setbacks. Its shadow covered surrounding streets and neighbouring buildings for much of the day, and neighbours complained about lost light and rents. It became the argument for regulation.

The 1916 Zoning Resolution

New York's 1916 resolution, the first comprehensive zoning code in the United States, did two things. It separated uses into districts, and it controlled bulk. Above a height tied to the width of the street, a building had to step back behind an imaginary inclined plane; once the building covered no more than a quarter of the lot, it could rise without limit. Architects such as Hugh Ferriss drew the envelope this allowed, and the setback skyscraper was the result.

1961 and floor-area ratio

The 1961 Zoning Resolution replaced the envelope with floor-area ratio: the total floor area allowed divided by the lot area. An FAR of 15 on a 10,000-square-foot lot allows 150,000 square feet, whether squat or slender. Bonuses for public plazas produced the flat-topped slab set back on an open plaza.

Rules elsewhere

Washington's Height of Buildings Act (1910) ties height to street width and keeps the capital low. Paris limited central heights for most of the twentieth century. Zoning, height limits, view corridors and air-rights transfers explain why cities with similar land prices have very different skylines. For a researcher, rules are the variable that separates economic height from permitted height.