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Your Guide to Building an Accessory Dwelling Unit (ADU) in NYC

By: The Nook Team

As New York City continues to tackle housing affordability and flexibility, Accessory Dwelling Units (ADUs) have emerged as a smart, sustainable solution for homeowners. Whether you're looking to create a granny flat for a loved one, convert your unused garage, or build a backyard cottage for extra income, Nook is here to help you navigate the process from start to finish.

What is an Accessory Dwelling Unit (ADU)?

An Accessory Dwelling Unit (ADU) is a secondary living space built on the same lot as a one- or two-family home. These units are self-contained with their own kitchen and bathroom and can only house one family. ADUs offer incredible flexibility. You can use one to keep family members close, generate passive rental income, or even age in place.

Who is eligible to build an ADU in NYC? 

Not every property qualifies for an ADU under current NYC regulations. Here’s what you need to know:

 

Property Type

 

Your property must be a single-family or two-family residence

 

Zoning Regulations

 

Each NYC property falls within a zoning district that determines what you can build. ADUs are allowed in many districts, but there are some key restrictions:

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  • Not permitted in R1A, R2A, and R3A zoning districts unless your property is located in a Greater Transit Zone

  • Not allowed in designated historic districts

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Not sure what zoning district you’re in?

Look it up on NYC’s Zoning & Land Use map or  Schedule a free consultation with us and we’ll do it for you. 

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Lot Size Requirements

Your property must meet specific minimum lot size criteria, and you can’t exceed the maximum floor area ratio. These requirements vary based on your zoning designation.

 

Not sure what this means? Schedule a free consultation with us and we’ll walk you through it!

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What Types of ADUs Can You Build?

 

Depending on your lot and home configuration, you might consider one of these popular ADU types:
 

  • Detached ADU in your backyard

  • Garage conversion into a livable unit

  • Basement conversion with a separate entrance

  • Attic or rooftop addition

  • Attached unit that connects directly to your home
     

Nook can help you determine which ADU type makes the most sense for your property, budget, and goals.

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Key Requirements to Consider

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To ensure compliance with NYC’s ADU regulations, your unit must meet the following standards:
 

  • Maximum size: 800 square feet

  • Owner occupancy: You must live on the property

  • No additional parking is required

  • Separate entrance: The ADU must have its own independent access

  • Independent utilities: Your ADU needs its own water, gas, and electrical connections
     

These rules help maintain safety and privacy for both primary and secondary households.

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The ADU Approval Process

 

Building an ADU in New York City involves several steps — and Nook handles every one of them for you:

 

1. Hire a Licensed Professional

Start by working with Nook’s licensed architects and ADU experts. We’ll map out your design vision, provide budget guidance, and handle all the paperwork so you don’t have to.
 

2. Submit Permit Applications

We’ll file all necessary plans and documents with the Department of Buildings (DOB), including payment of any required city fees.
 

3. Inspections

Throughout construction, Nook will coordinate and schedule all required DOB inspections to ensure your ADU meets code.
 

4. Manage Construction

We partner with trusted, vetted builders and manage the entire construction process to bring your vision to life — on time and on budget.
 

5. Get Your Certificate of Occupancy

Once construction is complete and inspections are passed, we’ll secure a Certificate of Occupancy from the DOB — and your ADU will be move-in ready!

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Ready to Build Your ADU? Nook is Here to Help


Whether you're dreaming of a garage conversion, a basement unit, or a custom backyard cottage, Nook is your one-stop partner for
building an ADU in New York City.
 

✅ Free consultation to evaluate your property
✅ Custom designs tailored to your goals and budget
✅ Full-service project management from design through final inspection
✅ Trusted contractor network that delivers quality builds
 

 

Ready to unlock the potential of your property?

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