Combining Townhouses NYC

by | Last updated Jul 14, 2020 | Multifamily Residential, Property Development

You can combine two adjacent townhouses in New York City. Combining Townhouses is an involved process requiring applications from many City Agencies including DOB Alt 1 filing a DOF Lot Merger, and multiple other filings dependent on individual circumstances.


Filing for Combining Townhouses in NYC

  • DOB Alt 1
  • DOF Lot Merger
  • Borough President’s Office Street Numbers
  • Landmarks (If Landmark Status)
  • HPD Certificate Of No Harassment (If SRO Restricted)
  • State Attorney General (For Multifamily Condos and Co-Ops)


DOB Alteration Type 1

The primary application for a townhouse combination will be filing an Alteration Type 1 (Alt 1) with the NYC Department Of Buildings (DOB). An Alt 1 is an application that results in a new Certificate Of Occupancy. Combining townhouses will always be filed as an Alt 1 if you are keeping portions of the existing buildings. If you are demolishing the 2 buildings and developing a new one that would be filed as an NB or New Building Application.


DOF Lot Merger

When combining townhouses the Department Of Finance (DOF) is where you file the lot merger. This is where you combine the 2 properties assuming they were originally 2 separate Tax Lots or Zoning Lots. To file a lot merger will include an RP602 application with all the necessary supporting documents such as a land survey and deed.


Borough President’s Office Street Numbers

When combining townhouses you will need to file with the Topographic Office in you respective Borough President’s Office. This office assigns street numbers even if you want to keep the original street number you will need to file an “Application For Street Number(s)”. This must be done in every case.


Landmarks (If Landmark Status)

If you are combining townhouses or going to combine two brownstones and either of the townhouses are Landmark Status you will need permits from the Landmarks Preservation Commission (LPC). This will apply to and buildings that are individually landmarked or buildings in a landmark district. Sometimes an entire block is landmark status. If you have no landmark status this will not apply to you.


HPD Certificate Of No Harassment (If SRO Restricted)

If your property is SRO restricted you will need to acquire a Certificate Of No Harassment from the NYC Housing Preservation and Development (HPD) office. This does not apply to properties that are not “SRO Restricted”. You can see another post we wrote to learn more about SRO Conversions.


State Attorney General (For Multifamily Condos and Co-Ops)

If you are combining two brownstones or more to make a multifamily Condo or Co-Op you will need to file with the State Attorney General’s Office as well as all applicable filings listed above. the Attorney General handles Co-Op and Condo Conversions.


Combining Two Brownstones or Townhouses

The terms Brownstones and Townhouses are usually used interchangeably. For a clear explanation on the terms please see another post we wrote explaining the Difference Between Townhouses and Brownstones.


NYC Codes

As an architect I study codes closely. NYC Codes are complicated and quite involved. In this article, we reviewed some of the basic requirements with regards to Combining Townhouses in NYC. This analysis does not assume to cover every possible issue or condition, but provide a general overview.


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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.