Why Most NYC Homeowners Still Can't Build an ADU Under City of Yes
Chris Koss, AIA|Published June 21, 2026|Last updated June 24, 2026
City of Yes for Housing Opportunity promised New Yorkers the right to add ADUs to their homes. A Regional Plan Association analysis finds that only 12% of the city's one- and two-family properties actually qualify.
Sadé Singh's home in St. Albans, Queens. Photo: Alex Krales/THE CITY, via The City Reporter.
In August 2024, a city car drove Sadé Singh from her home in St. Albans, Queens to a podium at City Hall, where she stood with Mayor Eric Adams and described accessory dwelling units as "a lifeline for people like me." When the City Council voted to approve City of Yes for Housing Opportunity in December 2024, an aide from City Hall texted Singh that the vote had passed and that her ADU was now allowed. More than a year and a half later, she still cannot build one. Her semi-attached two-story house sits a handful of blocks outside the transit proximity zone that permits detached backyard cottages. Her cellar ceiling is too low for a legal conversion. Her backyard cannot fit a code-compliant attached unit. Her story is not exceptional. A Regional Plan Association analysis of the city's housing stock under the new rules found that only 12% of the city's 565,400 one- and two-family lots actually qualify to build an ancillary dwelling unit under the post-City of Yes framework.
What City of Yes actually changed
City of Yes for Housing Opportunity, adopted by the City Council in December 2024, was the most significant zoning overhaul New York City had seen in decades. For the first time, the city explicitly permitted ADUs on lots with one- and two-family homes. Under Local Laws 126 and 127 of 2024, a homeowner can add an ancillary dwelling unit up to 800 square feet. The permitted configurations: converting a basement or cellar, converting an attic, building an addition attached to the main structure, or constructing a freestanding backyard cottage. One ADU per lot. No new parking required. The homeowner must live in the primary dwelling or the ADU.
On paper, those options cover a wide range of property types. In practice, the specific conditions embedded in each path cut the universe of eligible properties down sharply.
Why 88% of NYC one- and two-family homeowners still cannot build one
The RPA reviewed the city's housing stock against every condition embedded in the finalized Department of Buildings rules. The result: of 565,400 single- and two-family lots citywide, roughly 460,000 remain ineligible. That leaves about 68,000 lots where an ADU could actually be permitted, which is 12%.
The single biggest barrier is building type. The new rules apply only to detached and semi-detached one- and two-family buildings. Row houses, townhomes, and attached buildings (generally building classes A4, A5, B1, and B9) are excluded entirely. That produces 0% eligibility for roughly 219,900 attached lots. If your home shares both side walls with neighbors, the current City of Yes rules offer no ADU path at all.
Transit proximity for detached cottages. A freestanding backyard structure is only permitted within half a mile of most mass transit stations. In a last-minute carve-out covering 13 Long Island Rail Road stations in eastern Queens and four Metro-North stations in the Bronx, the permitted radius shrinks to a quarter mile. Singh's home in St. Albans, near the LIRR, missed that narrower boundary by a handful of blocks.
Dimensional rules. Even eligible lots face additional tests. The ADU must be within 100 feet of the street curb with a 5-foot-wide access path, at least 5 feet from lot lines, and (for detached structures) cover no more than 33% of the required rear yard. Small urban lots with shallow rear yards often cannot satisfy all three conditions at once.
Basement and cellar rules. Basement conversions must comply with Local Law 126's requirements, including minimum ceiling heights and the requirement that the floor-to-ceiling space rise at least two feet above the street curb line. Cellars below that threshold are ineligible. Units in high flood-risk areas designated by FEMA or DEP are excluded under either path. Singh's cellar fails the height test.
Historic districts and contextual zoning. Properties inside designated historic districts, and those in the low-density contextual zones R1A, R2A, and R3A that fall outside the Greater Transit Zone, are also ineligible. About 18% of one- and two-family lots carry one of these restrictions.
The numbers, by building type
For NYC homeowners researching ADUs right now, the RPA breakdown is the most useful single table to read before calling an architect:
Detached one- and two-family buildings: 29% of these lots (about 54,000 out of 185,400) are potentially eligible. These properties face fewer categorical barriers, though dimensional and location rules still apply.
Semi-detached buildings: 9% (about 14,500 out of 160,000 lots). Sharing one wall with a neighbor does not automatically disqualify a property, but lot configuration and setback requirements eliminate most.
Attached row houses and townhomes: 0% eligible under the current rules. The building-type exclusion is categorical, with no workaround.
Even within the 68,000 potentially eligible lots, RPA projects that only a fraction will convert into actual permitted units given owner interest, financing access, and construction capacity. In a scenario where one in five eligible properties eventually builds, that would mean roughly 13,600 new ADUs citywide, representing about 3.5% of the new housing the city projects through 2040. For comparison, the Los Angeles region permitted approximately 26,400 ADUs between 2018 and 2021 alone, representing 32% of new housing production in that period.
What to check before you hire an architect
If you own a one- or two-family home in New York City and are evaluating whether you can build an ADU, the sequence matters. Start with building type and lot configuration before spending money on drawings. The DOB's ADU page has building-type guidance and the full list of dimensional requirements. If you are in an attached row house or townhome, the current rules do not offer a path. If you are in a detached or semi-detached building, run the dimensional checks next: rear yard size, distance from curb, lot-line setbacks. Then check transit proximity if you want a detached cottage, and confirm you are not in a historic district or contextual zone.
The Plus One ADU program at HPD runs these eligibility screens automatically as part of its intake. From its first round, about 700 of the 2,600 applicants were found eligible based on zoning. Of those, about 200 submitted full loan applications, and 20 projects are currently in the pipeline. The most recent intake (March to June 2026) received more than 3,100 applications that are now under eligibility review. If you applied, that review is what to watch for. If you missed the deadline, the next intake period will be the time to run your address. Since October 2025, the Department of Buildings has approved permits for more than 30 ADU projects across the city, a number that illustrates both that some homeowners are getting through and that the volume remains limited by eligibility constraints.
A-du now works in New York City alongside its California operations. If you want a professional read on whether your lot qualifies before you invest in drawings, A-du's build marketplace connects you with architects and contractors who have already mapped the eligibility terrain across NYC neighborhoods.