Converting To Multi Family NYC

by | Last updated Jun 1, 2023 | Multifamily Residential, NYC DOB, Property Development

Many people who own single-family and two-family homes are interested in converting them to multifamily apartment buildings.


Can You Convert a Single-Family Home Into a Multifamily in NYC?

You can convert a single-family home into multifamily in NYC if it complies with all required zoning and building code requirements. To complete this conversion, you must perform all necessary upgrades and obtain a new certificate of Occupancy. 

I am Jorge Fontan, an architect in New York and owner of Fontan Architecture. In this post, we will explore some requirements for converting from a one or two-family house into a multifamily building. 


Converting To Multifamily 

I want to tell you that converting to multifamily may be more complicated than you think. We must assess every property on a case-by-case basis. The list below outlines just a few of the issues you may have to contend with when performing this type of alteration. Let’s start with a list of some basic requirements. 


  • Zoning
  • Elevator
  • Fire Alarm
  • Fire Sprinklers
  • ADA Accessibility
  • Construction Classification
  • More than One Means Of Egress
  • New Certificate of Occupancy


Multifamily Residential Zoning 

First, verify that you are in a suitable zoning district. NYC has different zoning districts that regulate what you can build. To convert to multifamily use, you must be in a multifamily residential zoning district.

Once you have determined that your zoning district allows for multifamily use, you must figure out the “Density Factor.” Every zoning district has a formula for determining the maximum number of dwelling units. 

You can always get a Zoning Analysis to see the development potential of your property. 


Conversion, Addition, or New Building

It may be the case that you can build an addition to your building. Sometimes it makes sense just to tear down the whole house and start from scratch. But if the structure is appropriate, you may consider building an addition. We wrote another post on Building Additions if you want to learn more about that option. You have to figure out what makes sense: converting, building an addition, or demolishing and building a new building.

Building Addition and Conversion to multifamily

Building Addition and Conversion to multifamily


Elevator Requirements for Multifamily Conversions

You will need an elevator if you convert to a multifamily and build an addition with five stories or more. All multifamily buildings over four stories require an elevator. 

By the way, basements are a story, but a cellar is not. Basements are less than 50% underground. A Cellar is more than 50% underground. See anothe


Thank You for Reading Our Blog Post on Converting To Multifamily.

If you would like to speak with an architect about a potential project, please feel free to contact us at Fontan architecture directly.


Contact Fontan Architecture


Jorge Fontan

Jorge Fontan

This post was written by Jorge Fontan AIA a Registered Architect and owner of New York City architecture firm Fontan Architecture. Jorge Fontan has earned 3 degrees in the study of architecture including two degrees from the City University of New York and a Masters Degree in Advanced Architectural Design from Columbia University. Jorge has a background in construction and has been practicing architecture for 20 years where he has designed renovations and new developments of various building types.