How to Build an ADU in Your NYC Home (2026 City of Yes Rules)

Under the City of Yes reforms, NYC homeowners with one or two-family homes can now legally add one Accessory Dwelling Unit, a basement apartment, garage conversion, attic, or backyard cottage. It can generate 1,500 to 3,500 dollars a month and add 20 to 30 percent to your property value. Here is how it works.

What is an ADU and is it legal in NYC now?

An Accessory Dwelling Unit is a self-contained living space on the same lot as your primary home, with its own entrance, kitchen, and bathroom. The City of Yes for Housing Opportunity, approved in late 2024 and phased in through 2025 and 2026, lets one and two-family homeowners add one ADU as of right in most residential zones, as long as they meet size and design standards and pull proper Department of Buildings permits.

What are the four types of ADUs?

Basement conversion, the most common and cost-effective; garage conversion, which works well on Staten Island; attic conversion, for homes with adequate head height; and a backyard cottage, which is new construction offering the most flexibility and privacy. The ADU must be at least 400 square feet, and you must live in either the primary home or the ADU.

How much does it cost to build an ADU in NYC?

Realistic NYC costs including architecture, permits, and finishes: basement conversion 50,000 to 100,000; garage conversion 60,000 to 120,000; attic conversion 40,000 to 80,000; and a backyard cottage 150,000 to 250,000 or more. Prices well below these usually mean corners cut or permits skipped.

Is an ADU worth it?

A Staten Island ADU renting for around 2,000 a month produces about 24,000 a year, often paying back an 80,000 build in three to four years. A legal, permitted ADU with a Certificate of Occupancy typically adds 20 to 30 percent to property value, roughly 150,000 to 225,000 on a 750,000 home. Financing options include a HELOC, renovation loan, or cash-out refinance.