New York wants to make it easier to build granny flats.
The city will provide new technical and financial support to homeowners who want to build accessory dwelling units — ADUs — on their properties, Mayor Zohran Mamdani is set to announce Tuesday. ADUs, or so-called granny flats, are independent residences on the same lot as one-family or two-family homes, and depending on location are also called in-law suites, backyard cottages or basement apartments.
The Landmarks Preservation Commission will release an online map that identifies where ADUs can be built in historic districts. The Department of Buildings will also streamline permitting for certain manufactured homes.
The changes are part of the mayor’s housing plan, set to be released Tuesday. The Mamdani administration has made enemies of multifamily landlords, but has continued to emphasize the importance of building new housing.
“We are setting the most ambitious housing production and preservation targets in the city’s modern history — and backing them up with investments to match — while also protecting tenants and homeowners, investing in public housing and ensuring the workers building that housing have good-paying, safe jobs,” said Mayor Mamdani in a statement.
The changes build on the city’s previous announcements related to ADUs. The city launched a website for homeowners in March with pre-approved plans and a guidebook, calling the set of tools “ADU for YOU.” The city and state have also created the Plus One ADU program to provide up to $395,000 in financial and technical support for homeowners in the building process.
Backyard ADUs are prohibited in historic districts, but other types of ADUs are allowed, including converted cellars, attics, and garages. The Landmarks Preservation Commission will create an online map of potential ADU locations, create a dedicated team to help property owners and consider rules to make the review process easier, according to the housing plan.
The buildings department will create rules to streamline permitting for certain manufactured homes, specifically “HUD Code” homes, referring to the Department of Housing and Urban Development. These manufactured homes are permitted nationally regardless of local building code, according to the mayor’s housing plan, although they still need to comply with local zoning. They can be purchased and installed in about one month, according to the plan.
The Mamdani administration has said creating an ADU on a property is one way for homeowners to bring in extra income and afford to stay in place. ADUs also increase the supply of rental housing, a stated priority of the city.
The changes build off City of Yes for Housing Opportunity, the zoning overhaul from Mayor Eric Adams’ administration that permitted some ADUs as-of-right. ADUs are now allowed on the lots of one and two-family homes, provided they are under 800 square feet, the owner lives on the lot, and other site-specific conditions are met. This amendment was met with some resistance from residents over fears it would “manhattanize” their quieter more residential neighborhoods.
The Adams administration estimated 25,000 housing units would be built from its ADU changes.