DOB and HPD Announce Proposed Rules for Ancillary Dwelling Units

For Immediate Release: June 18, 2025
CONTACT: dobcommunications@buildings.nyc.gov, (212) 393-2126

DOB AND HPD ANNOUNCE PROPOSED RULES FOR ANCILLARY DWELLING UNITS

New Proposed Rules Provide Details on Safe, Code-Compliant Dwelling Units, as Administration Implements "City of Yes"

New York, NY - Mayor Eric Adams, the Department of Buildings (DOB), and the Department of Housing Preservation & Development (HPD) announced this week the publication of new proposed agency rules needed to implement the ancillary dwelling unit (ADU) provisions of City of Yes for Housing Opportunity, the city's wide-ranging initiative to build more housing for New York City families. These rules, along with new proposed rules for Department of Environment Protection (DEP) flood mapping and Department of Health and Mental Hygiene (DOHMH) requirements for vapor testing, will implement Local Law 127 of 2024 and City of Yes by providing specific requirements for the creation of safe, accessible and Code-complaint ADUs, including basement apartments, cellar apartments, attic apartments, and backyard cottages at existing residential one- and two-family homes throughout the five boroughs. The city is currently experiencing a multi-decade housing shortage, with historically low vacancy rates. The creation of legal ADUs under the City of Yes initiative provides an innovative way to gradually increase housing in neighborhoods throughout the city where denser large-scale housing development is prohibited.

"Today, our administration is taking an important step toward unlocking thousands of safe, legal homes for New Yorkers," said New York City Mayor Eric Adams. "Ancillary dwelling units are a solution to our city's housing crisis that allow homeowners to create new homes for family members or renters while keeping our neighborhoods vibrant and livable. Through 'City of Yes,' we're giving New Yorkers more housing options, more flexibility, and more opportunity, block by block and borough by borough as make New York City the best place to live and raise a family."

"We must say 'yes' to a little more housing everywhere, and that includes in our own backyards" said Adolfo Carrion, Jr., Deputy Mayor or Housing, Economic Development, and Workforce. "Today's announcement to advance new rules to allow for the creation of ancillary dwelling units is yet another key step this administration is taking to be the most pro-housing administration in our city's history."

"Our city's affordability and safety must be our north star; legalizing and making ancillary units safe does both," said Deputy Mayor for Operations Jeff Roth. "By establishing these new rules, we are creating a path forward towards good, safe housing for more New Yorkers, a continuing and real cascade of wins off of the legacy-making City of Yes."

"DOB is committed to a thoughtful and straightforward approach to implementing these provisions of City of Yes that emphasizes keeping our fellow New Yorkers safe," said Buildings Commissioner Jimmy Oddo.

"HPD's mission is simple: build and preserve more housing to ensure that every New Yorker has a safe, affordable place to call home. Today's announcement is an important step in building a bit more housing in every neighborhood across New York City and is a part of our continued efforts to tackle the housing crisis head-on," said HPD Acting Commissioner Ahmed Tigani. "ADUs can make a meaningful difference in many ways-whether by offering expanded space for a growing family or creating a new home for someone just starting out. With the right direction and guidance, ADUs represent a powerful opportunity to provide affordable, flexible living spaces for New Yorkers who need them most."

"Accessory dwelling units are a proven solution to create much-needed housing, helping older New Yorkers age in place or middle-class homeowners bring in extra income. Ensuring that New Yorkers could access the benefits of ADUs was a critical part of City of Yes," said Dan Garodnick, Director of the Department of City Planning. "These new rules are another important step forward to create a little more housing in every neighborhood and address our city's housing crisis."

Read the Proposed Rules Here.

Multiple agencies, including FDNY, NYCEM, DOHMH, and DEP, coordinated to determine the language of these proposed rules to provide safety features and administrative requirements necessary to implement City of Yes for Housing Opportunity, Local Law 127 of 2024, and the recent associated changes in the Zoning Resolution for single- and two-family homes. Included in the proposed rules are:

• Implementation of ADUs at one- and two-family homes first included in the city's Building Code Appendix U (Local Law 127 of 2024);

• Administrative requirements for identifying ADU filings and includes requirements for Certificates of Occupancy

• Establishment of technical requirements for ADUs including flood mitigation, water sensors, entrance identification, and occupancy restrictions

• Requirements regarding egress, sprinklers and windows for ADUs located in cellars

The Department of Buildings will hold a public hearing for this proposed rule on August 18, 2025. Members of the public are welcome to provide public comment in writing or verbally during the scheduled online hearing. The department will review and consider all public comments submitted for this rule before publishing a final adopted version of the rule which is expected to occur later this year.

The Plus One ADU Program will combine low or no-interest capital loans from the NYC Department of Housing Preservation and Development and grant funding from the New York State Homes and Community Renewal for eligible homeowners to build or convert ADUs on their property. In partnership with Restored Homes HDFC, the program will provide homeowners with financial and technical support, including predevelopment and construction resources on a single-family property where zoning allows for the creation of an ADU. ADUs financed through the program will become safe, habitable, and potentially rent-restricted units that will help homeowners generate additional income and support long-term homeowner and neighborhood stability. To assist any New York City homeowner interested in creating or maintaining an ADU on their property, HPD will roll out a one-stop resource hub for those who want to explore adding an ADU to their property.

In addition to the proposed DOB agency rules announced today and the ongoing work of HPD, our partner agencies at (DEP) and the New York City Department of Health and Mental Hygiene (DOHMH) have also initiated parallel rulemaking, which are critical to the implementation of the city's ADU program. DEP has proposed a new agency rule creating updated interim flood risk area map, showing the 10-year rainfall flood risk area and the coastal flood risk area, in order to delineate specific flood hazard areas where ADU would be prohibited due to the increased flood risk. DOHMH has proposed a new agency for the certification process regarding the maximum allowable levels of radon and certain organic chemical vapors found in a basement or cellar areas for the safety of occupants in proposed ADUs.

These multiagency efforts are critical steps needed to fully implement City of Yes for Housing Opportunity, the city historic plan to allow for a little more housing in every neighborhood through a suite of important zoning updates. These include legalizing small ADUs, permitting three-, four-, and five-story apartment buildings near transit and along commercial corridors, encouraging more income-restricted affordable housing citywide, rolling back parking mandates, and more. The initiative, as adopted, is expected to enable 82,000 new homes over the next 15 years and comes with $5 billion for critical infrastructure and housing.