ADU Regulations in District of Columbia (DC)
District of Columbia is rated Moderate for ADU construction with an ADU-friendliness score of 65/100 (ADU-Friendly). District of Columbia has a statewide ADU law that sets baseline rules across all municipalities. Owner must reside on the property. No additional parking required for ADUs. One accessory apartment is allowed as a matter of right in most R zones (11-U DCMR § 253), with owner occupancy required (§ 253.5) and a cap of 3 occupants. There is no flat square-footage cap: an apartment inside the house may occupy up to 35% of the house's gross floor area (§ 253.7(b)), while a detached accessory building's footprint is capped at the greater of 450 sq ft or 30% of the required rear yard area, max 2 stories/20 ft (11-D DCMR §§ 5006.1, 5002.1).
Full ADU Regulations Summary for District of Columbia
| ADUs Allowed | Yes |
| Statewide ADU Law | Yes |
| Maximum ADU Size | Set locally |
| Owner Occupancy Required | Yes |
| Parking Required | No |
| Minimum Setback | 3 ft |
| Permitting Timeline | 90 days |
| Impact Fees | None |
| Long-Term Rental Allowed | Yes |
| Short-Term Rental (Airbnb) Allowed | No |
| Ease of Building | Moderate |
ADU Regulations by City in District of Columbia
ADU rules can vary by city even within the same state. While District of Columbia's statewide law sets minimum standards, some cities have additional local provisions. Below are ADU details for 1 cities in District of Columbia.
Washington
ADUs (called 'accessory apartments') allowed by right in residential zones. Must be 900 sq ft or less. Owner occupancy required. No additional parking. Building permit required.
How District of Columbia Compares to Other States
Below is a comparison of District of Columbia with five states that have similar ADU-friendliness scores. This comparison helps illustrate where District of Columbia stands nationally.
| State | Score | Statewide Law | Parking Req? | Owner Occ? | Ease |
|---|---|---|---|---|---|
| District of Columbia (DC) | 65 | Yes | No | Yes | Moderate |
| Florida (FL) | 58 | No | No | No | Easy |
| Colorado (CO) | 75 | Yes | No | No | Easy |
| Connecticut (CT) | 75 | Yes | No | No | Easy |
| Hawaii (HI) | 75 | Yes | No | No | Moderate |
| New Hampshire (NH) | 55 | Yes | Yes | Yes | Moderate |
Frequently Asked Questions About ADUs in District of Columbia
Can I build an ADU in District of Columbia?
Yes, ADUs are allowed in District of Columbia. District of Columbia has a statewide ADU law that requires local jurisdictions to permit ADUs on residential lots. This means your city cannot outright ban ADUs. The ease of building is rated "Moderate" with a friendliness score of 65/100.
Do I need to live on the property to have an ADU in District of Columbia?
Yes, District of Columbia generally requires owner occupancy — the property owner must live either in the main house or the ADU. This means you cannot rent out both units simultaneously.
How big can an ADU be in District of Columbia?
District of Columbia does not set a statewide maximum ADU size — this is determined by your local jurisdiction. Common local limits range from 600 to 1,200 square feet. Check your city's zoning code for the specific maximum.
Do I need extra parking for an ADU in District of Columbia?
No — District of Columbia does not require additional parking for ADUs. This is a significant advantage, as parking requirements are often the biggest barrier to ADU construction on smaller lots.
Can I rent out my ADU in District of Columbia?
Long-term rentals of ADUs are allowed in District of Columbia. Short-term rentals (like Airbnb) of ADUs are restricted in District of Columbia — you can rent to long-term tenants but not as a vacation rental.
How long does it take to get an ADU permit in District of Columbia?
The permitting timeline in District of Columbia is: 90 days. The statewide law sets maximum review periods that cities must comply with.
Does District of Columbia have a statewide ADU law?
Yes. State law sets the floor that District of Columbia cities must meet: no statewide size cap, owner occupancy may be required, no added parking, with permitting handled as: 90 days. Cities can be more permissive than the state baseline but generally not stricter.
Check ADU Rules for Your City
Use our ADU regulations lookup tool to find the specific rules for your city in District of Columbia, or browse all 50 states to compare ADU regulations across the country.