County Board Adopts Zoning Standards for New Accessory Dwellings

Published on May 18, 2019

Today the County Board voted to allow residents to build new detached accessory dwellings and made it easier to convert existing accessory buildings into accessory dwellings through several amendments to the County's Zoning Ordinance.

The approved changes:

  • Establish minimum side and rear yard setback distances of 5 feet for new detached accessory dwellings on interior lots;

  • Establish a minimum side yard setback distance of 5 feet, and a minimum rear yard setback distance of 10 feet, for new detached accessory dwellings on corner lots; and

  • Allow greater flexibility for converting existing accessory buildings into detached accessory dwellings.

"Our community has been engaged in a years-long conversation about accessory dwellings," Arlington Board Chair Christian Dorsey said. "As we have moved incrementally to loosen restrictions on accessory dwellings, we have held fast to the goals of increasing Arlington's supply of homes affordable to more households while ensuring that any accessory dwellings blend harmoniously with our existing neighborhoods. The Zoning Ordinance changes approved today preserve those goals."

The Zoning Ordinance changes will enable older adults to age in place, help house family members, provide a lower priced housing alternative, and enable homeowners to receive additional income from the rental.

In adopting these amendments, the County Board has provided a new option to residents who are interested in establishing accessory dwellings, in addition to the previously permitted accessory dwelling within the main dwelling and the conversion of an existing accessory building. With this update, residents can now create a new detached accessory dwelling, along with the other types of accessory dwellings, by right on properties across Arlington with one-family dwellings. County staff will continue to monitor the development of accessory dwellings and assess the need for further refinements to the zoning regulations.

These updates to Arlington's accessory dwelling standards will help expand affordable and "missing middle" housing options as part of the Housing Arlington initiative. Housing Arlington combines ideas, tools and best practices to advance an inclusive housing community grounded in equity, opportunity, stability and adaptability.

The County Board voted 5 to 0 to approve the changes. To read the staff reportgo to the County website and scroll down to Item No. 45.


In Arlington, an accessory dwelling is an independent dwelling, with kitchen and bath, that houses at most three people. The County permits accessory dwellings in residential districts on lots that contain one-family dwellings. An accessory dwelling may be located within, or attached to, the main dwelling, as in the case of a basement apartment or an addition, within an existing detached accessory building, such as a garage or guesthouse, or within a newly-constructed detached accessory building.

Accessory dwellings help to meet a variety of housing needs. They can provide lower-priced housing alternatives that are integrated into single-family neighborhoods. They enable property owners to receive additional rental income and/or allow them to remain in a home otherwise too large for their needs. Accessory dwellings can offer solutions for seniors seeking to age in place and can increase the supply of rental housing for older adults and persons with disabilities.

Learn more about Arlington County's efforts to promote affordable and "missing middle" housing at the kick-off event for Housing Arlington on Wednesday, May 29, from 6-9 p.m., at Wakefield High School.