Permit Required? Required
Typical Fee Range $200–$2,500 (Application & Filings) Includes $200 initial fee for Plus One program; total fees calculated on project valuation and DOB NOW filing types.
Fee Method Valuation-based
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What's Required in New York City

  • Maximum size of 800 square feet for detached backyard cottages (City of Yes 2026 rules).
  • Must be located on a lot with an existing one- or two-family home.
  • Property owner must occupy either the primary residence or the ADU.
  • Basement ADUs must have a minimum ceiling height of 7 feet and comply with flood zone restrictions.
  • Must be located outside of FEMA Special Coastal Risk Districts or 2050 Stormwater Flood areas.
  • Fire Department (FDNY) access must be maintained to the rear of the property for detached units.

How Much Does an ADU Permit Cost in New York City?

Budget $200–$2,500 (Application & Filings) for the New York City permit itself (valuation-based), issued by the NYC Department of Buildings — but treat that as the entry fee, not the total. ADUs are full dwelling units, so the permit stack usually includes building, electrical, plumbing, and mechanical trade permits, plus plan review. One local note: includes $200 initial fee for Plus One program; total fees calculated on project valuation and DOB NOW filing types. Get an itemized fee estimate from the department before finalizing your budget; the spread between a simple conversion and a new detached build is wide.

ADU Size Limits and Zoning Rules in New York City

Before drawing plans, check the two gates that sink most ADU projects: size and zoning. On record here, the size ceiling is 800 square feet for detached backyard cottages (City of Yes 2026 rules). Other recorded conditions: must be located on a lot with an existing one- or two-family home; property owner must occupy either the primary residence or the ADU. Setbacks, height limits, and utility connections layer on top of those rules. The NYC Department of Buildings can confirm what your specific lot allows — worth doing before you pay for architectural drawings rather than after.

How to Get a ADU Permit in New York City

1

Step 1: Zoning Verification

Confirm lot eligibility under the 'City of Yes for Housing Opportunity' zoning amendments.

2

Step 2: Hire a Registered Professional

A licensed Architect or Engineer must prepare and seal the construction documents.

3

Step 3: DOB NOW Filing

Submit the application through the 'DOB NOW: Build' portal for plan review.

4

Step 4: Permit Issuance

Pay all applicable filing fees and obtain the official work permit to begin construction.

5

Step 5: Inspection & Sign-off

Schedule final inspections and obtain a Certificate of Occupancy or Letter of Completion.

Frequently Asked Questions

Yes, under the 2026 City of Yes rules, detached ADUs up to 800 sq ft are permitted on single-family lots.
The program application is $200, but total DOB filing fees vary based on construction costs (approx. $15 per $1,000).
Yes, the homeowner must live on-site in either the main house or the newly created unit.
On record, the ceiling is 800 square feet — with the exact limit depending on ADU type and lot. Confirm your configuration with the NYC Department of Buildings.