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, and 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. This is allowed for all ADUs except LL126 Pilot units (which need DOB review).
source · reviewed 2026-06-22
New York City ADU permit questions
- Do I need a permit to build an ADU in New York City?
- Yes. An accessory dwelling unit (ADU) in New York City requires a building permit. ArchPermit tracks 13 cited requirements for this jurisdiction (7 required, the rest conditional). Always confirm the exact forms, fees, and code edition with the local permitting authority that issues the permit.
- What does an ADU permit package require in New York City?
- Core required items include: ADU Questions in PW1; NYCECC Energy Compliance + Energy Analysis (EN); PW1: Plan/Work Application; Plans / Construction Documents (signed & sealed by RA/PE); Schedule of Occupancy (ADU as a Use); TR1: Technical Report (special/progress inspections), plus 1 more. Each requirement links to its authoritative source, and nothing is permit-ready until an independent licensed professional reviews and seals it.
- How are ADU permits submitted in New York City?
- New York City accepts permit submittals via DOB NOW: Build. ArchPermit prepares a draft package you can submit there after a licensed architect reviews and seals it.