Accessory Structures in Washington, DC (2026)
4 verified accessory structures rules for Washington, District of Columbia, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
The District allows one accessory apartment per lot in residential zones under 11 DCMR-U § 253, capped at 35% of the house's gross floor area and three occupants (six if it's in the R-1B/GT or R-3/GT zone), with size and access conditions that differ for units inside the main house versus a separate accessory building.
Washington DC Accessory Apartment Zoning Rule
Some Restrictions11 DCMR-U §§ 253.1, 253.6, 253.7(b)
One (1) accessory apartment may be established in an R zone, subject to the provisions of this section... The total number of persons that may occupy the accessory apartment shall not exceed three (3), except in the R-1B/GT or R-3/GT zone where the aggregate number of persons that may occupy the house, including the principal dwelling and the accessory apartment combined, shall not exceed six (...
ADU Owner Occupancy
An accessory apartment in the District only stays legal as long as an owner lives on the property. 11 DCMR-U § 253.5 requires either the principal dwelling or the accessory apartment to be owner-occupied for as long as the accessory unit is in use, and § 253.10(a) blocks the Board of Zoning Adjustment from waiving that requirement in any residential zone.
Washington DC Accessory Apartment Owner Rule
Significant Restrictions11 DCMR-U §§ 253.5, 253.10(a)
Either the principal dwelling or accessory apartment unit shall be owner-occupied for the duration of the accessory apartment use... (a) The owner-occupancy requirement of Subtitle U § 253.5 shall not be waived in any R zones;
ADU Rental Restrictions
Before an owner can rent out an accessory apartment anywhere in the District, 11 DCMR-U § 253.13 requires a Residential Rental Business License from the Department of Consumer and Regulatory Affairs plus a housing-code inspection of the property, on top of the zoning conditions that already govern the unit itself.
Washington DC Accessory Apartment Rental License
Some Restrictions11 DCMR-U § 253.13
Prior to renting an accessory apartment in any zone, the property owner shall obtain a Residential Rental Business License from the Department of Consumer and Regulatory Affairs and the property shall be inspected for relevant housing code compliance.
Shed & Carport Rules
DC zoning caps a shed at 50 square feet and 10 feet in height under its own definition, and gives sheds a setback exemption other accessory buildings don't get: a shed can sit inside a required rear or side yard where larger accessory structures cannot.
Washington DC Backyard Shed Size Rules
Some Restrictions11 DCMR Subtitle B § 100.2; Subtitle D §§ 5002.1, 5003.1, 5004.2, 5005.2
Shed: An accessory building, not used for habitable or automobile purposes, that does not exceed 50 square feet (50 sq. ft.) in area and is less than 10 feet (10 ft.) in overall height. ... 5004.2 A shed may be located within a required rear yard of a principal building. ... 5005.2 A shed may be located within a required side yard of a principal building.