Alexandria City, VA Accessory Structures: ADU Rules (2026)

Alexandria's ADU framework emerged from a multi-year community process and was adopted by City Council on January 23, 2021. ADUs are defined as secondary, independent living units with separate kitchen, sleeping, and bathroom facilities, and may take the form of basement apartments, converted garages, or new detached structures associated with a primary residence. Under the adopted policy, the property owner must reside on site at the time of application and during construction of the ADU. Setbacks for detached ADUs are tiered by height: structures under 13.5 feet require a 1-foot setback; 13.5 to 16 feet require a 2.5-foot setback; and 16 to 20 feet require a 5-foot setback. The ordinance expressly prohibits using an ADU exclusively as a short-term rental, ensuring ADUs serve long-term housing needs. An administrative permit fee in the range of $75 to $100 applies. Detailed standards (size limits, parking, allowed zoning districts, design rules) are found in the Alexandria Zoning Ordinance section on Accessory Dwellings, accessible through the Municode zoning library and administered by the Department of Planning & Zoning. As of recent reporting, 43 ADUs have been approved citywide since 2021 (31 detached, 12 internal).