In December 2024, NYC passed the City of YES for Housing Opportunity with the aim to create approximately 80,000 new homes throughout the city. One of the key goals is to create smaller accessory units. Like backyard cottages and legalizing cellar and basement apartments, also known as Ancillary Dwelling Units (ADU’s).
City of Yes will allow ADUs in one and two family homes in all low density (R1-R-5) zoning districts. Certain areas prohibit certain types of ADUs such as if you are in a flood zone.
Some general requirements for ADUS are:
- Only one ADU per each 1- or 2- family residence with a maximum size of 800 sf.
- The homeowner must reside on the zoning lot with the ADU
- ADUs require a separate entrance
- Creation of the ADU must not affect the light and air requirements of the primary dwelling.
- Subject to the Multiple Dwelling Law (MDL), two-family building adding an attic, basement, cellar, or attached ADU will be treated as a three-family building. There is an exception to units separated by a fire wall
- A two-family building with a pre-existing basement or cellar unit undergoing the legalization process will be subject to Building Code Appendix U and additional fire and safety rules and regulations in lieu of the MDL.
Exceptions/Restrictions
Backyard ADUs are not permitted in:
- Historic Districts
- R1-2A, R2A and R3A districts outside of the Greater Transit Zone
- Special Bay Ridge District west of Ridge Boulevard or south of Marine Avenue
Conversions of existing garages to an ADU are not backyard ADUs according to the Zoning Resolution Sect. 12-10 .
Subgrade ADUs are not permitted in high-risk flood areas
LL126/24 are the laws that control subgrade dwelling legalization. Subgrade dwellings are restricted to existing one- and two-family buildings in the program area. The program area includes:
Community Districts :
- 9, 10, 11, and 12 in the Bronx,
- 4, 10, 11, and 17 in Brooklyn,
- 2, 3, 9, 10, 11, and 12 in Manhattan
- And district 2, in Queens.
More information will be available as the city planning commission updates the Zoning Texts. For questions about ADUs, reach out to S & M Expediting.


