Washington ADU permit requirements
Last reviewed: June 22, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in Washington, District of Columbia means pulling a building permit from the local authority that issues it. ArchPermit tracks 13 source-cited requirements (9 required, the rest conditional) for this jurisdiction. Submittals go through DOB Permit Wizard → ProjectDox. 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 Washington. Every item links to its authoritative source; items that vary are flagged to confirm locally.
An accessory apartment is matter-of-right in almost all R (residential house) zones under Zoning Regulations Subtitle U § U253 (subject to its owner-occupancy, minimum-house-size, ≤35%-gross-floor-area, and entrance conditions), except R-19 and R-20, where it requires BZA special-exception approval; a special exception is also needed to build a NEW accessory building to house the unit. Where the space looks like an independent dwelling but is permitted as part of the principal unit, the Zoning Administrator requires a recorded Declaration of Covenants before the permit issues (ZA-031).
- Architectural Plans / Construction Documentsrequired
Construction documents reviewed for compliance with the building codes and zoning regulations.
source · reviewed 2026-06-22 - Completed Permit Application (DOB Permit Wizard)required
One-/two-family ADU permits are filed in the DOB Permit Wizard; all required fields completed and accurate before submission.
source · reviewed 2026-06-22 - Cover Sheet (DOB template)required
The completed DOB cover sheet; a template and sample are provided.
source · reviewed 2026-06-22 - Estimated Cost of Constructionrequired
The estimated/total construction cost is required at application; the 50% filing fee is based on it.
source · reviewed 2026-06-22 - Floor Plans (existing + proposed)required
Floor plans showing the existing and proposed structures.
source · reviewed 2026-06-22 - Residential Project Checklist (online)required
DOB requires applicants to complete the online residential checklist of minimum plan-review requirements before an application can be submitted.
source · reviewed 2026-06-22 - Signed Construction Contract / Formal Quoterequired
Upload a formal quote, contract agreement, or MS report to pay the filing fee; the remaining balance is based on the signed contract.
source · reviewed 2026-06-22 - Surveyor's Plat (DC-certified)required
Scaled drawing of the lot certified by the DC Surveyor showing lot lines, record dimensions, and existing + proposed structures; required for all exterior work.
source · reviewed 2026-06-22 - Zoning Code Analysis (Subtitle U § U253 compliance)required
For an accessory apartment, the U253 conditions (owner-occupancy, minimum gross floor area by zone, ≤35% GFA, entrance restrictions, occupancy limit) must be met and demonstrated.
source · reviewed 2026-06-22 - BZA Special-Exception Approvalconditional
Required in R-19/R-20 zones and to construct a new accessory building to house the unit; otherwise matter-of-right under U253.
source · reviewed 2026-06-22 - Certificate of Occupancyconditional
Required for Apartment and Two-Family Rental classifications (single-family in R-1A/R-1B/R-2/R-3 is exempt) to legally occupy/rent the new unit.
source · reviewed 2026-06-22 - Declaration of Covenants (recorded)conditional
Where the space has independence + bathroom + cooking characteristics but is permitted as part of the principal unit, a recorded covenant must be furnished to the Office of the Zoning Administrator before permit issuance (ZA-031).
source · reviewed 2026-06-22 - Structural Plans / Engineer of Recordconditionalverify locally
Structural drawings where structural work is involved; basement/below-grade ADU conversions typically trigger this. Confirm the exact engineer threshold on the residential checklist.
source · reviewed 2026-06-22
Washington ADU permit questions
- Do I need a permit to build an ADU in Washington?
- Yes. An accessory dwelling unit (ADU) in Washington requires a building permit. ArchPermit tracks 13 cited requirements for this jurisdiction (9 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 Washington?
- Core required items include: Architectural Plans / Construction Documents; Completed Permit Application (DOB Permit Wizard); Cover Sheet (DOB template); Estimated Cost of Construction; Floor Plans (existing + proposed); Residential Project Checklist (online), plus 3 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 Washington?
- Washington accepts permit submittals via DOB Permit Wizard → ProjectDox. ArchPermit prepares a draft package you can submit there after a licensed architect reviews and seals it.