Do I Need a Permit to Build an ADU in Washington, DC?

ADU-specific overview

What makes this different from a simple accessory structure

Pulled from the city's ADU guidance and linked code references.

Permit type: Residential building permit through the DC Department of Buildings (DOB), filed online through the DC Access portal. DC terminology is 'accessory apartment'; the building permit type is residential new construction or addition depending on the scope.
Maximum size: DC's 2016 Zoning Rewrite governs accessory apartment size through the subordinate-use standards in 11 DCMR. The accessory apartment must remain subordinate to the primary dwelling in size and use. Verify the specific size limit applicable to the zone district and lot configuration with the DC Office of Zoning at dcoz.dc.gov.
Setbacks: Accessory apartments must comply with the rear yard and side yard setback requirements of the applicable 11 DCMR subtitle for the zone district. Detached accessory structures in DC typically require a minimum 3-foot rear setback and must comply with lot occupancy limits. Verify requirements for the specific zone with the DC Office of Zoning.
Owner occupancy: Not required. DC's 2016 Zoning Rewrite explicitly removed the owner-occupancy requirement that had applied to accessory apartments under the prior zoning code. A property owner in DC is not required to reside on site as a condition of permitting or operating an accessory apartment.
Parking: Additional off-street parking is generally not required for an accessory apartment in DC's urban residential zones. Verify whether the specific zone district has parking requirements with the DC Office of Zoning, particularly for lower-density R-1 zones.
Utilities: Accessory apartments in DC may share utilities with the primary dwelling or have separate service connections. A new utility service or meter requires coordination with Pepco (electric), Washington Gas, and DC Water. Separate metering is common for rental units. Confirm utility requirements with the relevant utility provider and DOB.
JADU distinction: DC does not use a California-style Junior ADU (JADU) designation. Smaller accessory apartments created by internal conversion within the existing primary structure are treated as attached accessory apartments under DCMR Title 11 and follow the same DOB building permit path as a new detached unit.

Washington, DC is a federal district — not a state or municipality under any state — with its own complete set of construction and zoning codes. DC's rules are entirely independent of Maryland and Virginia and are not subject to any statewide preemption framework.
Historic district coverage in DC is extensive. Large portions of Capitol Hill, Dupont Circle, Georgetown, Logan Circle, LeDroit Park, Mount Pleasant, Takoma, and many other neighborhoods are within designated historic districts. Approximately one-quarter of DC's land area has historic protection of some kind. Check HPO status early.
DC DOB was separated from DCRA (DC Dept of Consumer and Regulatory Affairs) in October 2021 and is now a standalone agency. The correct URL for building permits is dob.dc.gov. DC Access (dcaccess.dc.gov) is the online portal for all permit applications and inspection requests.

Fees

Estimated city fees

Baseline for a simple permitted adu: $1,100–$2,700 estimated combined fees (permit + plan review + technology surcharge) for a typical new accessory apartment in Washington, DC; excludes BZA or HPO fees if applicable

Fee	Amount	Notes
Building permit fee	Valuation-based (estimated $800–$2,000 for a typical accessory apartment)	DC DOB charges building permit fees based on declared construction valuation. Verify current amounts at dob.dc.gov using the fee schedule.
Plan review fee	Percentage of permit fee (estimated $300–$700)	DC charges a plan review fee as a percentage of the building permit fee. Combined permit and plan review for a new accessory apartment typically runs $1,100–$2,700. Verify current amounts at dob.dc.gov.
Technology surcharge	$15–$25	DC charges a technology surcharge on permit transactions processed through the DC Access online portal.
Zoning fee (Board of Zoning Adjustment, if required)	Varies	If the proposed accessory apartment requires a special exception or variance from the Board of Zoning Adjustment (BZA), application fees and hearing costs apply. BZA proceedings add significant time.
Historic preservation review (if applicable)	Varies by scope	Properties in DC historic districts or those on the DC Inventory of Historic Sites require a Certificate of Appropriateness from the DC Historic Preservation Office (HPO) before a building permit can be issued. COA application fees and review timelines vary by project scope and district.

Documents

Required documents

DOB permit application submitted through the DC Access online portal at dcaccess.dc.gov.
Site plan showing property lines, existing structure, proposed accessory apartment footprint, setback dimensions, and impervious surface coverage.
Architectural drawings including floor plans, elevations, cross sections, and roof plan, complying with the 2017 DC Building Code (based on the 2015 IBC/IRC with DC amendments).
Structural plans or engineering calculations for non-prescriptive elements of new construction or substantial structural modification.
Energy code compliance documentation per the DC Energy Conservation Code (DC adoption of IECC).
DC licensed contractor information — all contractors performing permitted work in DC must hold a current DC DOB-issued contractor's license.
Workers' compensation certificate and general liability insurance certificate for the contractor, as required by DC DOB.
Certificate of Appropriateness (COA) issued by the DC Historic Preservation Office (HPO), if the property is in a designated historic district or listed on the DC Inventory of Historic Sites and the proposed work is subject to HPO jurisdiction.
Zoning compliance documentation confirming the accessory apartment meets 11 DCMR setback, lot occupancy, and rear yard requirements for the applicable zone district.

Timeline

Typical timing

Plan review: 4–8 weeks for standard plan review; DOB posts current queue estimates at dob.dc.gov
Total cycle: 8–20 weeks typical from permit application to permit issuance; total project time including construction and inspections varies

Historic Preservation Office (HPO) review for a Certificate of Appropriateness adds 4–12 weeks before the DOB building permit application can be submitted and must be treated as part of the critical path. BZA special exception or variance proceedings can add 4–6+ months.

Process

How the permit process works

Identify the zone district and verify accessory apartment eligibility Use the DC Zoning Map at maps.dcoz.dc.gov to confirm the parcel is in an R-1-A, R-1-B, R-2, R-3, R-4, or RF residential zone district. Review the applicable 11 DCMR subtitle to confirm the accessory apartment use is permitted and the proposed size, setbacks, and lot configuration will comply.
Check for historic district or landmark designation Use the DC Historic Preservation Office map at planning.dc.gov/historic to determine if the property is in a designated historic district or listed on the DC Inventory of Historic Sites. Historic district coverage is extensive in DC — it includes large portions of Capitol Hill, Dupont Circle, Georgetown, Logan Circle, Mount Pleasant, and many ward neighborhoods. If the property is in a historic district and the proposed work is visible from the public way or otherwise covered by HPO jurisdiction, a Certificate of Appropriateness (COA) must be obtained from HPO before applying for a DOB building permit.
Obtain Certificate of Appropriateness (if applicable) Submit a COA application to the DC Historic Preservation Office at planning.dc.gov. HPO staff review for compliance with design guidelines applicable to the historic district or property type. HPO review can take 4–12 weeks or longer for complex projects. The COA must be in hand before DOB will issue a building permit for properties subject to HPO jurisdiction.
Engage a DC-licensed contractor and prepare the permit package All permitted construction in DC must use a contractor holding a valid DC DOB contractor's license. Prepare site plan, architectural drawings, structural documents, and energy code compliance materials. DC construction code is the 2017 DC Building Code (based on IBC/IRC 2015 with DC amendments).
Submit through DC Access portal File the building permit application and upload all plans through DC Access at dcaccess.dc.gov. Pay the plan review fee at intake. DC DOB coordinates concurrent review by building code and DC Office of Zoning as part of the standard review workflow.
Respond to plan review comments DC DOB reviewers and DC Office of Zoning staff will issue correction notices if plans require changes for building code, zoning, energy code, or structural compliance. Address all corrections and resubmit through DC Access to advance the application.
Pay remaining fees and receive the permit After plan approval, pay the building permit fee and technology surcharge through DC Access. DC DOB issues the permit electronically. Post the permit at the job site in a visible location before construction begins.
Complete inspections and close the permit Schedule required DOB inspections (footing, framing, insulation, mechanical, final) through the DC Access portal. After all inspections pass, DC DOB closes the permit. The accessory apartment may not be lawfully occupied or rented without a closed permit and, for a new unit, a Certificate of Occupancy.

Code basis

What Washington reviews against

DCMR Title 11 (DC Zoning Regulations, 2016 Zoning Rewrite), 2017 DC Building Code (based on 2015 IBC/IRC with DC amendments), DC Energy Conservation Code (IECC adoption), and DC Historic Preservation Review Board (HPRB) design guidelines for properties within historic districts.

Residential permit page Washington permit portal

If you skip the permit

What can go wrong

DC DOB can issue a Stop Work Order and require all construction to cease immediately for any work performed without a valid building permit.
DC code enforcement can assess daily fines and place liens on the property for continued violations.
An unpermitted accessory apartment in DC cannot be lawfully occupied or rented; it lacks a Certificate of Occupancy.
After-the-fact permitting for unpermitted work is significantly more expensive and time-consuming, and may require exposing completed construction for inspections.
An unpermitted accessory apartment in a DC historic district triggers separate HPO enforcement exposure in addition to DOB building code enforcement.
DC real estate disclosure requirements and lender/title company review increasingly flag unpermitted dwelling units, creating complications during property sales or refinancing.

FAQ

Common Washington adu permit questions

Do I need a permit for an accessory apartment (ADU) in Washington, DC?

Yes. Any accessory apartment — whether created by internal conversion, addition, or new detached construction — requires a building permit from the DC Department of Buildings (DOB) filed through the DC Access portal. DC uses the term 'accessory apartment' rather than ADU, but the permit requirement and process are the same concept.

What is the difference between an 'accessory apartment' and an 'ADU' in DC?

They are the same concept. DC's Zoning Regulations (DCMR Title 11) use the term 'accessory apartment' to describe a secondary dwelling unit created on a lot with an existing principal dwelling. Other jurisdictions call the same type of unit an ADU. If you're searching DC DOB or DCOZ materials, use 'accessory apartment' to find the applicable regulations.

Does DC require the owner to live on site for an accessory apartment?

No. DC's 2016 Zoning Rewrite explicitly removed the owner-occupancy requirement that had applied under the prior code. DC does not require the property owner to reside in the principal dwelling or the accessory apartment as a condition of permitting or renting the unit.

What if my DC property is in a historic district?

Historic district coverage in DC is extensive — approximately one-quarter of DC land is in a designated historic district or has some form of historic protection. If your property is within a historic district or listed on the DC Inventory of Historic Sites, you must obtain a Certificate of Appropriateness (COA) from the DC Historic Preservation Office (HPO) at planning.dc.gov before DC DOB will issue a building permit. HPO review typically takes 4–12 weeks and must be treated as a sequential prerequisite in your project timeline.

How do I know if my DC property is in a historic district?

Use the DC Historic Preservation Office map at planning.dc.gov/historic to check historic district designation and landmark status for your address. Common DC historic districts include Capitol Hill, Dupont Circle, Georgetown, Logan Circle, Mount Pleasant, LeDroit Park, Takoma, and many others. When in doubt, contact HPO directly before beginning design work.

How long does a DC accessory apartment permit take?

DOB plan review typically takes 4–8 weeks. Total time from application to permit issuance is often 8–20 weeks. If your project requires a Certificate of Appropriateness from HPO, add 4–12 weeks before the DOB application can even be filed. BZA special exception or variance proceedings can add 4–6+ months on top.

Are there parking requirements for an accessory apartment in DC?

Generally no — DC's urban residential zones typically do not require additional off-street parking for an accessory apartment. However, parking requirements can vary by zone district. Verify the parking standard for your specific zone with the DC Office of Zoning at dcoz.dc.gov or through a pre-application meeting with DC DOB.

Sources

Official links and freshness

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