Current Status of ADU Laws in New York City
In December 2024, New York City Council voted to adopt the City of Yes Housing Opportunity, a massive zoning text amendment aimed at addressing the city’s housing shortage by making it possible to “build a little more housing in every neighborhood”. Included within the housing plan is Local Local 127, which defined and legalized ADUs in the NYC zoning code and added Appendix U: Ancillary Dwelling Units to the building code.
While the new zoning amendments became effective in June 2025, NYC property owners have to wait until two city rules are passed before filing permit applications for ADUs. Most city rules are adopted 3 to 4 months after the public hearing, which means homeowners can likely begin filing ADU permit applications in November or December 2025.
DEP Interim Flood Risk Area Map
The first city rule is the Department of Environmental Protection’s adoption of an interim flood risk area map. This map is referenced in the new zoning text, and properties located inside in the DEP’s flood risk area are not allowed to build basement or backyard ADUs. The public hearing for this rule was held on July 30, 2025.
DOB Rule Relating to Ancillary Dwelling Units
The second city rule is the Department of Building’s rules relating to ancillary dwelling units in 1 and 2 family buildings. This rule provides safety and administrative requirements necessary to implement the ADU zoning code and building code regulations. The public hearing for the DOB ADU rule was held on August 18, 2025.
When Should I Begin Planning My ADU?
In all likelihood, the DEP and DOB city rules will go into effect in November or December of 2025. Most small construction projects like ADUs take anywhere from 4 to 12 weeks to plan and design, so it’s not too early to begin planning your project.
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