Density Factor / Dwelling Unit Factor
Density Factor is a zoning term for the maximum allowable number of residential units one can develop on a property. The allowable residential square footage of the building is divided by the density factor to determine the allowable number of units. These factors vary in different zoning districts. Density factor is also known as Dwelling Unit Factor.
Zoning Basics : Density Factor
Density Factor Definition
The following is based on The New York City Zoning Resolution.
Density Factor is a formula for determining how many dwelling units can be placed on a lot. The density factor or dwelling unit factor is based off the zoning district for that location. The zones are divided into lower and higher densities. It is NYC`s way of regulating density throughout the city.
Finding Your Density Factor
In order to calculate your density factor you need to calculate your Maximum Buildable Area, which you can find information to do so in our Floor Area Ratio post. Once you have that you will have found your zoning district and below you will find your Factor For Dwelling Unit based on that.
DU Factor NYC Zoning
|District||Factor for Dwelling Units||Special Notes|
|625||R3-2 for single and two family detached and semi-detached residences only|
|900||R4 Ifill & R5 infill In Predominantly Built Up Area only.|
|R5B||1,350||for lots with less than 40 feet street frontage and existing on the date of establishing the R5B districts on the zoning map.|
|680||This goes for all R6 - R10 Districts including subdistricts and contextual zoning.|
DENISTY FACTOR CALCULATION
Maximum Buildable Area for Residential X Factor for Dwelling Units = Dwelling Units Allowed
Maximum Buildable Area = 9,000 SF
Zoning District = R6
Factor for Dwelling Units = 680
Maximum Buildable Area /Factor for Dwelling Units = Number of Dwelling Units Allowed
9,000 SF / 680 = 13.23
13 Units would be allowed
DENSITY FACTOR KEY POINTS TO CONSIDER
- You can only round up Density Factor if you have a value with .75
- “Small zoning lots“ are restricted to 1 and 2 families even if the density factor allows for more then 2.
DWELLING UNIT COUNT
Your maximum unit count will tell you how many apartments you can put on a lot. You can also use it to see if you can expand and existing building to add more apartments to it
THANK YOU FOR READING OUR POST ON DENSITY FACTOR AND DWELLING UNIT CALCULATIONS.
We hope this post was helpful and we wish you the best of luck with your project. Please feel free to leave comments or questions below. If you are interested in speaking with an architect you can contact us directly and we will be happy to hear about your upcoming project.
Author Jorge Fontan AIA
This post was written by Jorge Fontan, a Registered Architect and owner of Fontan Architecture.