How many ADUs have been filed in NYC?

323 distinct ADU projects have been filed with the NYC Department of Buildings and verified filing-by-filing against DOB records, as of October 1, 2026. That figure counts properties, not filings: one property can have several DOB filings.

Which borough has the most ADU projects?

Queens, with 193 of the 323 projects. The other four boroughs have 130 ADU projects between them: Staten Island 75, Bronx 32, Brooklyn 21, Manhattan 2.

What kinds of ADUs are New Yorkers building?

Attached 132, basement or cellar 107, detached 40, garage 34 and attic 7. Another 3 filings do not state a type. Attached and basement or cellar ADUs are the two most common, together about 74 percent of all projects.

Where does this ADU data come from?

NYC Department of Buildings job filings, published through NYC Open Data. Second Key verifies each one filing-by-filing against DOB records, using the filing description or the DOB NOW PW1 ADU declaration, and groups filings by property so a project is counted once. The map is refreshed monthly; it was last updated October 1, 2026.

The NYC ADU Project Map

Name: The NYC ADU Project Map
Creator: Second Key
License: https://www.secondkeynyc.com/

A free map of every ADU project filed with the NYC Department of Buildings, verified filing-by-filing against DOB records. 323 projects as of October 1, 2026. Updated monthly.

SECOND KEY · NYC ADU PROJECT MAP

Every verified ADU project in New York City

323 projects since the program opened · hover or tap a dot

one ADU project Showing all 323 verified ADU projects, updated October 1, 2026 Verified filing-by-filing against DOB records by Second Key · Source: NYC DOB filings via NYC Open Data

NYC ADU Project Map · Key Numbers

323

ADU projects across New York City, verified filing-by-filing against DOB records.

By boroughQueens 193 · Staten Island 75 · Bronx 32 · Brooklyn 21 · Manhattan 2

By ADU typeAttached 132 · Basement or cellar 107 · Detached 40 · Garage 34 · Attic 7 · Type not stated 3

Status97 have a DOB permit, 18 are approved and waiting on one and 208 are still in DOB review.

Median cost$195,500 as declared in DOB filings · 218 of the 323 projects state one

Last updated October 1, 2026. Source: NYC Department of Buildings filings via NYC Open Data.

Queens accounts for 193 of the 323 projects, more than the other four boroughs combined (130). Two ADU types make up about 74 percent of the 323: 132 attached ADUs and 107 subgrade ADUs (basement or cellar). Filing volume is rising — from 98 projects filed in 2025 to 220 filed in the first 9 months of 2026. Permit issuance lags well behind application filing. Of the 323 projects, 97 have pulled a DOB permit and 208 are still in DOB review. DOB records show no certificate of occupancy for any of them yet.

Methodology

The source is NYC Department of Buildings job filings, published through NYC Open Data. Second Key reads every candidate filing and verifies it filing-by-filing against DOB records: either the filing's own description names an ADU, or the DOB NOW PW1 application answers that the scope of work includes one.

One property can carry several DOB filings, so this page counts distinct properties rather than filings — a property with three filings is counted once. A project enters the count if it was filed or reviewed as an ADU on or after June 1, 2025.

Declared construction cost is the number the applicant puts on the DOB filing, and it is usually lower than what the work costs to build. The count is a floor, not an audited figure: a filing from before the window opened whose description never uses the word ADU is not searched for, so projects like that are missing from the count.

What we deliberately do not publish: owner names, contact details, addresses and DOB job numbers. This page is compiled and verified by Second Key, a licensed New York City general contractor. It is not a City of New York product and is not affiliated with the Department of Buildings or HPD.

The rules that decide whether a property qualifies are in our NYC ADU eligibility guide, and our analysis of the filing data covers the trends behind the map.

Frequently Asked Questions

323 distinct ADU projects have been filed with the NYC Department of Buildings and verified filing-by-filing against DOB records, as of October 1, 2026. That figure counts properties, not filings: one property can have several DOB filings.
Queens, with 193 of the 323 projects. The other four boroughs have 130 ADU projects between them: Staten Island 75, Bronx 32, Brooklyn 21, Manhattan 2.
Attached 132, basement or cellar 107, detached 40, garage 34 and attic 7. Another 3 filings do not state a type. Attached and basement or cellar ADUs are the two most common, together about 74 percent of all projects.
Of the 323 verified projects, 97 have a DOB permit, 18 are approved and waiting on one and 208 are still in DOB review. DOB records show no certificate of occupancy for any of them yet. The program is young: the Zoning Resolution's definition of an ancillary dwelling unit (ZR 12-10) dates to December 5, 2024.
NYC Department of Buildings job filings, published through NYC Open Data. Second Key verifies each one filing-by-filing against DOB records, using the filing description or the DOB NOW PW1 ADU declaration, and groups filings by property so a project is counted once. The map is refreshed monthly; it was last updated October 1, 2026.

Thinking about building an ADU of your own?

These are other people's projects. Second Key builds ADUs in Queens, Brooklyn, Staten Island and the Bronx. If you want to know what you can build on your own property and how much it will cost, sign up for a free assessment.

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