The anniversary of the real estate funnel

Before the enactment of NYC zoning laws landowners where allowed to build anything they wanted on their property – and the City was unable to object.  This week celebrates the 100 year anniversary of NYC zoning regulations put in place after a public uproar following the construction of the Equitable Building located at 120 Broadway.


Picture of the Equitable building

Despite its beauty and current NYC Landmark Preservation Commission status, this build was reviled because it was not only massive and tall but it was built to the edge of the property line and went up so many floors that it blocked light from surrounding buildings.  The overall scale of it gave pedestrians and neighbors a feeling of being oppressed by its sheer size.


Zoning solved two crucial problems:  the use of the property and the size and massing of the buildings.

Zoning Planners realized organized that certain uses where not compatible with each other-for example it was not good to have a manufacturing operation next to an apartment building.  So they created districts that where designated as Commercial (think offices), Residential (think places people live and ancillary uses such as doctors offices) and Manufacturing (think factories) districts each with many classifications and use groups which in turn further refine the allowable use of the property.  For example: Manufacturing districts M1-1 through M1-3 districts allow for a building that is 1 to 10 stories high (more on this later).  Use Groups in an M1 districts allow for light manufacturing whereas M-3 allow heavy manufacturing.  Because of the latter’s noxious uses they typically not mapped adjacent to residential Zones.  Because its impact on residents is less that Manufacturing, Commercial zones are usually mapped as a buffer between Residential and Manufacturing uses.

Zoning density tends to be lower on the 60′ “narrow” side streets (say West 85th street between Amsterdam and Columbus) and greater along the 100′”wide” avenues on Columbus Avenue,.

The best way of explaining Zoning in NYC is to think of a funnel that restricts liquids as it passes through it (in this case it restricts the size and shape of the ultimate building). Here are the different items that constrain the “flow” of the funnel:

For our example we will use an example of a 100′ * 100′ interior lot in an R-9X zone,on a through-lot, on a 60′ wide street.


View of a typical building in an R9-X district

FAR:  Floor area ratio is usually expressed as a number such as 2.43, 7.o, 10.0, etc..  This means that if you have a 10,000 SF lot in a R-9X district which is allowed a 9.0 FAR then you can build a building that is nine stories or a total of 90,000 SF.

CORNER LOT:  If you have a corner lot you are usually allowed to build on the entire lot.  The alternative is an Interior or Through lot which usually allows you to build less than the entire lot because you have to provide setbacks.

WIDTH OF STREET/MAXIMUM BUILDING HEIGHT:  Most NYC street are 60′ wide but our main avenues a wider.  Maximum building height vary so as not to obstruct light.  Our max. height is 160 feet – vs 170 ft if the building where in a wide street.

LOT COVERAGE:  this is usually expressed as a percentage in the R-9X Interior Lot case its 70%.  This means that if you have a 10,000 SF lot in a R-9x district you cannot occupy more than 70% of the size of your land.  This restriction made you shrink your floors from 10,000 SF to 7,000SF.

SETBACKS:  Buildings have to be built some distance from the adjacent lots and from the street.    Most NYC buildings have a mandatory rear setback, no side setback and in some instances a front setback.  In our example, the building needs to be set back 15 feet from the front of the lot AND 30 feet from the rear – no setbacks with the neighbors.  So now the funnel allows you to build only on approx. 5,500 SF (100 feet of depth minus 15 feet front setback minus a 30 foot rear setback equals a 55 foot-wide building; multiplied by 100 feet of frontage).

PARKING REQUIREMENTS:  this is usually expressed as a percentage of the total units developed and in the R-9X case its 40% of the apartment units have to have a parking space (there is usually no parking requirement for buildings with where the only access is on an avenue) .  In this case, we assume we can fit 100 apartments, then we would need 40 parking spaces.  Even though this requirement mandates what a developer usually does below grade parking, it does affect the number of apartments one can fit upstairs and still accommodate the requisite mechanical,  bicycle,amenity rooms, etc.

BASE HEIGHT:  Zoning planners wanted NYC streets to feel like they rise like walls of a canyon.  Planners wanted uniformity and a common street appearance so they mandated that buildings in certain districts, in addition to have a maximum building height, that they was a minimum and maximum wall height to create that canyon before they start to set back.  In our case, the height is a minimum of 60 ft and a maximum of 120 feet.

SETBACKS:  The space between the maximum building height and minimum base heights gets developed in a terraced-like shape to allow sun to reach the streets below.  It is sometimes called a “wedding cake” design.  The setback line usually follows an imaginary line between the street opposite your building and the maximum building height (technically called “sky exposure plane”).


Setback and Base Height illustration of an R9-X building


Other restrictions where the creation of  overlay districts that regulate the uses on areas where uses overlap and they are called overlays.  Overlays occur when for example you have a residential building on a major avenue with a lot of pedestrian traffic.  By allowing commercial uses on the first 2 floors, the Zoning sought to foment street traffic and make the streets come to life.


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