What Other States Can Teach NYC About ADU Success
New York City has only recently given homeowners the green light for Accessory Dwelling Units (ADUs), officially joining the real estate movement that’s been thriving for years in California, Oregon, and Massachusetts.
This marks an exciting new phase for NYC housing. As the city begins to adapt, we can look to other states’ programs to see what’s worked well, and what’s served as a learning lesson.
California: The Gold Standard
California has approved more than 200,000 ADUs since its 2016 statewide reform. In 2024 alone, 41,125 units were permitted, with over 80,000 completed. ADUs are now common in cities like Los Angeles, San Diego, and Berkeley.
What NYC can emulate:
Pre-approved plans: Many California cities offer free pre-approved ADU blueprints to avoid long review processes. Want a 600 square foot backyard cottage? Choose a plan, pay a flat fee, and start building.
Owner-occupancy waivers: NYC requires you to live on the same zoning lot as the new ADU, but California removed that rule in 2022, allowing small landlords and nonprofits to invest.
Fee exemptions: ADUs under 750 sq ft are often exempt from impact fees, connection fees, and property-tax reassessment.
The takeaway: Faster builds, lower costs, and wider access.
Oregon: Financing for Fairness
In 2019, Oregon became the first state to eliminate single-family zoning, allowing duplexes, triplexes, and ADUs in all residential areas.
The state also launched the ADU Loan Program, providing 0% loans up to $75,000 for low- and moderate-income homeowners to build or legalize units. The program prioritizes Black, Indigenous, and other historically marginalized homeowners, helping to address equity gaps in homeownership.
Massachusetts: Simplify and Convert
Boston and its suburbs face challenges similar to NYC - aging housing stock, tight infill lots, and strict preservation codes. Massachusetts found success by focusing on conversions rather than new construction.
Their secret:
Simplified rules for internal ADUs, like converting a basement or attic with minimal renovation.
Ministerial approval: If your plans meet code, the city must approve them; no lengthy hearings.
For NYC, this model makes perfect sense. NYC should follow Massachusetts’ lead by making internal conversions the simplest, fastest, and most affordable path - with clear checklists and expedited permits.
Vermont & Maine: Statewide Support
Vermont’s 2022 “by-right” ADU law requires all municipalities to allow at least one ADU per single-family lot, no exceptions. Maine offers property-tax exemptions for ADUs rented below market rates.
Why does this matter for NYC? It shows that strong state leadership can override local resistance and scale housing solutions. If New York State followed suit, introducing tax credits, statewide financing, or ADU requirements in suburban zones, it could accelerate adoption far beyond what the city can do alone. Right now, NYC is doing it alone but real success will require state partnership and support.
Lessons NYC Can Take Forward
It’s an exciting time for New York real estate. Looking to the future, ADUs will become increasingly common, and could transform thousands of lives.
Here’s what NYC and New York State can borrow from other states’ success stories:
Standardize: Offer pre-approved ADU designs and flat permitting fees.
Subsidize: Provide low-interest loans for moderate-income homeowners.
Accelerate: Approve any plan that meets building code automatically.
Center equity: Direct resources to marginalized communities.
Legalize first: Prioritize legalizing existing units before building new ones.
Conclusion
The best new housing in a city facing a major housing crisis may come from the old space we’ve overlooked all along. By learning from states that have already paved the way, New York can turn its backyards, basements, and attics into one of the most powerful, and equitable, housing solutions of the decade.