How many ADUs have been filed in NYC?

300 distinct ADU projects have been filed with the NYC Department of Buildings and verified filing-by-filing against DOB records, as of August 31, 2026. That figure counts properties, not filings: one property can have several DOB filings.

Which borough has the most ADU projects?

Queens, with 181 of the 300 projects. The other four boroughs have 119 ADU projects between them: Staten Island 65, Bronx 33, Brooklyn 19, Manhattan 2.

What kinds of ADUs are New Yorkers building?

Attached 118, basement or cellar 97, detached 39, garage 33 and attic 6. Another 7 filings do not state a type. Attached and basement or cellar ADUs are the two most common, together about 72 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 August 31, 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. 300 projects as of August 31, 2026. Updated monthly.

SECOND KEY · NYC ADU PROJECT MAP

Every verified ADU project in New York City

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

one ADU project Showing all 300 verified ADU projects, updated August 31, 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

300

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

By boroughQueens 181 · Staten Island 65 · Bronx 33 · Brooklyn 19 · Manhattan 2

By ADU typeAttached 118 · Basement or cellar 97 · Detached 39 · Garage 33 · Attic 6 · Type not stated 7

Status76 have a DOB permit, 20 are approved and waiting on one and 204 are still in DOB review.

Median cost$185,082 as declared in DOB filings · 198 of the 300 projects state one

Last updated August 31, 2026. Source: NYC Department of Buildings filings via NYC Open Data.

Queens accounts for 181 of the 300 projects, more than the other four boroughs combined (119). Two ADU types make up about 72 percent of filings: 118 attached ADUs and 97 subgrade ADUs (basement or cellar). Filing volume is rising — from 97 projects filed in 2025 to 199 filed in the first 8 months of 2026. Permit issuance lags well behind application filing. Of the 300 job applications filed, 76 have pulled a DOB permit and 204 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

300 distinct ADU projects have been filed with the NYC Department of Buildings and verified filing-by-filing against DOB records, as of August 31, 2026. That figure counts properties, not filings: one property can have several DOB filings.
Queens, with 181 of the 300 projects. The other four boroughs have 119 ADU projects between them: Staten Island 65, Bronx 33, Brooklyn 19, Manhattan 2.
Attached 118, basement or cellar 97, detached 39, garage 33 and attic 6. Another 7 filings do not state a type. Attached and basement or cellar ADUs are the two most common, together about 72 percent of all projects.
Of the 300 verified projects, 76 have a DOB permit, 20 are approved and waiting on one and 204 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 August 31, 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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