New York City ADU permit requirements
Last reviewed: June 22, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in New York City, New York means pulling a building permit from the local authority that issues it. ArchPermit tracks 13 source-cited requirements (7 required, the rest conditional) for this jurisdiction. Submittals go through DOB NOW: Build. These requirements were last reviewed June 22, 2026; confirm the exact forms and fees with the local permitting authority.
A source-cited checklist of what an ADU (accessory dwelling unit) permit package needs in New York City. Every item links to its authoritative source; items that vary are flagged to confirm locally.
Under 'City of Yes for Housing Opportunity' (Local Laws 126/127, eff June 16 2025; ADU filing in DOB NOW opened Sep 30 2025), ADUs are newly legal — but legalization is PARTIAL and geographically restricted: backyard ADUs are prohibited in historic districts, in certain low-density districts outside the Greater Transit Zone, and the Special Bay Ridge District; basement/cellar + backyard ADUs are prohibited in FEMA/coastal/10-year-rainfall flood-risk areas; and the LL126 subgrade (basement/cellar) legalization pilot is NOT yet open. ADUs file as an Alt-CO or New Building job, usually via Professional Certification; a NY Registered Architect or PE must prepare, sign/seal, and file. The ADU is Occupancy Group R-2/R-3, ≤800 sf, and must meet Building Code Appendix U.
- ADU Questions in PW1required
New mandatory PW1 fields (scope-includes-ADU; ADU location; main-entrance-opens-to) exposed when the scope includes an ADU.
source · reviewed 2026-06-22 - NYCECC Energy Compliance + Energy Analysis (EN)required
PW1 Section 10 energy-code statement plus an Energy Analysis (Tabular / REScheck / COMcheck / EN1 modeling) submitted with the plans.
source · reviewed 2026-06-22 - PW1 — Plan/Work Applicationrequired
The core DOB NOW: Build application that begins the filing; specifies job/work type, applicant, and triggers all conditional documents.
source · reviewed 2026-06-22 - Plans / Construction Documents (signed & sealed by RA/PE)required
Architectural/structural drawings demonstrating Building Code Appendix U compliance (egress, light/air, fire separation, utility shutoffs, sprinklers); PW1 Section 7.
source · reviewed 2026-06-22 - Schedule of Occupancy (ADU as a Use)required
Must list 'Ancillary Dwelling Unit' as a use under Occupancy Group R-2 or R-3; drives the Certificate of Occupancy.
source · reviewed 2026-06-22 - TR1 — Technical Report (special/progress inspections)required
Identifies the special and progress inspections required by the NYC Construction Codes; completed by the associated inspector.
source · reviewed 2026-06-22 - Zoning Characteristics (PW1 Sec. 12)required
Use, zoning floor area, district, FAR, lot and yard details — establishes the ADU meets the ≤800 sf and lot/district limits.
source · reviewed 2026-06-22 - Asbestos Compliance (ACP-5 / DEP control number)conditional
For alterations (common for basement/attic conversions): an asbestos investigation/ACP-5 with a DEP control number, or a documented exemption (PW1 Section 22).
source · reviewed 2026-06-22 - DOHMH Radon & Vapor-Intrusion Mitigation Certificationconditionalverify locally
Required for basement/cellar (subgrade) ADUs before TCO; the DOHMH rule/instructions are still in development (exact form not yet published).
source · reviewed 2026-06-22 - House Number Verification (Borough Topographical Bureau)conditional
Detached / fire-wall-separated ADUs needing a new BIN must obtain address/house-number verification from the Borough Topographical Bureau.
source · reviewed 2026-06-22 - PD1 — Plot Diagramconditional
Required prior to approval for New Buildings (e.g. detached/backyard ADUs) and for Alt-COs when an enlargement is proposed.
source · reviewed 2026-06-22 - Pre-Approved ADU Plan Numberconditional
If using a design from HPD's Pre-Approved Plan Library, enter its number on PW1 — optional, speeds review.
source · reviewed 2026-06-22 - Professional Certification Statement (PC1)conditional
If filing Pro-Cert, the RA/PE certifies the documents comply with the Code — allowed for all ADUs except LL126 Pilot units (which need DOB review).
source · reviewed 2026-06-22