New York, NY Accessory Structures: ADU Rules (2026)
ADU rules in New York, NY, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Code Section
- NYC Zoning Resolution § 12-10 (definition); Article II Ch. 3
- Enabling action
- City of Yes for Housing Opportunity (adopted Dec. 5, 2024); Local Laws 126 & 127 of 2024
- Max ADU size
- 800 sq ft of floor area
- Eligible homes
- 1- or 2-family residences (one ADU each)
- Owner occupancy
- Required at initial occupancy
- Detached building height
- 2 stories / 25 ft, whichever is less
- Footprint limit
- Up to 1/3 of rear yard / rear yard equivalent
- Setback (free-standing)
- 5 ft from rear or side lot line; 10 ft between residences
- Basement/cellar ceiling height
- 7 ft clear (Building Code Appendix U)
- Flood prohibition
- No basement/cellar ADU in SFHA, 10-yr rainfall, or coastal flood risk areas
Summary
New York City legalized Ancillary Dwelling Units (ADUs) citywide on December 5, 2024 through the City of Yes for Housing Opportunity text amendment. An ADU is an additional dwelling unit of up to 800 square feet permitted on the same zoning lot as a single- or two-family residence, limited to one ADU per residence and requiring owner primary-residency.
An "ancillary dwelling unit" is an additional dwelling unit, permitted on the same zoning lot as a single- or two-family residence that does not exceed eight hundred square feet of floor area. Only one ancillary dwelling unit shall be permitted per every single- or two-family residence on a zoning lot. At the time of initial occupancy for an ancillary dwelling unit, the zoning lot on which the ancillary dwelling unit is located must be the primary residence of an owner of such zoning lot.
Full Breakdown
" Only one ADU is permitted per single- or two-family residence on a zoning lot, and at the time of initial occupancy the zoning lot must be the primary residence of an owner of such lot. The framework was created by the City of Yes for Housing Opportunity zoning text amendment adopted by the City Council on December 5, 2024, together with Local Laws 126 and 127 of 2024 amending the Administrative Code and Building Code (new Appendix U). ADUs may be created as conversions of existing space (a portion of the home, an attached or detached garage, or a basement/cellar), as additions to the home, or as new detached backyard cottages.
Bulk rules in Article II Chapter 3 limit a detached building containing an ADU (including one over an accessory parking space) to two stories or 25 feet above adjoining grade, whichever is less, including the apex of a pitched roof; the building footprint may not exceed one-third of the rear yard or rear yard equivalent; a free-standing ADU building must be set back at least five feet from a rear or side lot line; and a minimum distance of 10 feet must be maintained between residences and the ADU on the same zoning lot. 5 requires a minimum 7-foot clear ceiling height for habitable rooms in basements and cellars.
Violations & Fines
Creating an ancillary dwelling unit without DOB approval is unlawful construction/occupancy subject to civil penalties, stop-work orders, and Environmental Control Board violations. Local Law 126 of 2024 also established a multi-year pathway for legalizing certain pre-existing, unpermitted basement and cellar apartments, but units must be brought into compliance with the Building Code and Appendix U.
Frequently Asked Questions
Are ADUs legal in New York City?
Can I convert my garage into an ADU in NYC?
Does an ADU have to be on an owner-occupied lot?
Sources & Official References
Other rules in New York
How New York compares: Easiest Cities to Build an ADU·New York rules heatmap·Compare New York to another location·View the New York accessory structures overview
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