Building Envelope Conundrum

A case-study examination of the hurdles in NYC’s zoning and housing regulations that prevent buildings from reaching their full potential as prescribed, creating an inefficiency that robs the city’s housing stock of units.

The de Blasio administration’s Housing New York plan has set many ambitious goals for the development of new housing in the city – and has acknowledged that extra floor area for residential construction will be necessary.

CHPC’s board members are on the front lines of developing affordable housing. As such, they provide valuable insights into how the city can construct more housing, and improve its design and quality.

Recently, some of our board members had begun to raise an issue they had been experiencing that was constraining residential development. The rules that define the building envelope within contextual zoning were making it difficult, sometimes impossible, to fit the allotted floor area into their building. The building envelope defines the maximum three-dimensional shape that a new building can occupy.

We decided to take a closer look at how the building envelope rules within contextual zoning can sometimes result in fewer residential units being built.  We examined seventeen sites to see how much the building envelope rules affected the residential construction.

Our study found that eight out of the seventeen buildings were unable to use all of their allotted floor area because of the building envelope rules. In other words, it is often the building envelope that is the determinant of the development capacity of a new building rather than its floor area.

Our study helped to begin a dialogue with the Department of City Planning to see how these rules, put in place decades ago, could best be changed to reflect the realities of constructing residential buildings in New York City today. And this work became the Zoning for Quality and Affordability text amendment that passed the City Council in March. Throughout 2015, we worked with DCP to help them to develop the technical details of the text change and we served as an educational resource for Community Boards, the City Planning Commission and Council Members throughout the public review process.