Arlington County Accessory Building and Detached Garage Setbacks

In Arlington County residential districts, a detached garage or accessory building under 25 feet in height can be built as close as 1 foot to the side or rear property lines on interior lots, measured from the edge of the eave. On corner lots, the structure must maintain a 1-foot side setback but requires a 10-foot setback from the rear property line. All accessory structures in Arlington County must generally be set back at least 25 feet from any street right-of-way line [§3.2.6.A.1.e, §3.2.6.A.2.c].

Side and Rear Yard Setbacks in Residential (R) Districts

Arlington County establishes specific distances for accessory buildings based on the height of the structure, the size of its footprint, and the type of lot (interior versus corner). These regulations apply to the R-5, R-6, R-8, R-10, and R-20 districts.

Standard Accessory Buildings and Detached Garages

For a new detached accessory building to qualify for the minimum 1-foot setback, it must be less than 1.5 stories or 25 feet in height. Additionally, the footprint must be smaller than 560 square feet in Arlington County R-5 and R-6 districts, or smaller than 650 square feet in all other R districts [§3.2.6.A.2.c.2].

Large or Tall Accessory Buildings

Accessory structures that exceed two stories or 25 feet in height are subject to more restrictive placement rules to ensure compatibility with the surrounding Arlington County neighborhood [§3.2.6.A.2.c.2].

Structure Type	Feature	Interior Lot Setback	Corner Lot Setback
Standard Accessory (<25' height)	Side Property Line	1 foot (to eave)	1 foot (to eave)
Standard Accessory (<25' height)	Rear Property Line	1 foot (to eave)	10 feet (to eave)
Large/Tall Accessory (>25' or 2+ stories)	Any Side/Rear Line	10 feet (to wall)	10 feet (to wall)
All Accessory Buildings	Distance from Main Building	8 feet	8 feet
Large/Tall Accessory	Distance from Main Building	15 feet	15 feet

Street and Front Yard Setbacks

Regardless of the side or rear yard allowances, any structure built in Arlington County must adhere to setbacks from public streets.

General Street Setback: For all one-family dwellings and their accessory structures (including detached garages), no structure may be located less than 25 feet from any street right-of-way line [§3.2.6.A.1.e].
Centerline Rule: No structure in Arlington County may be located closer to the centerline of any street than 50 percent of the height of the building [§3.2.6.A.1].
Visual Clearance: On corner lots in Arlington County R and RA districts, no structure or obstruction to vision is permitted between a height of 3 feet and 10 feet above the curb level within the "sight triangle" (formed by the street lines and a line connecting them 25 feet from their intersection) [§3.2.6.A.4.a].

Additional Placement Regulations

Arlington County identifies several other proximity and structural requirements for accessory buildings:

Main Building Proximity: No wall of a standard accessory building may be located closer than 8 feet to any wall of the main dwelling. For accessory buildings two stories or taller, this distance increases to 15 feet [§3.2.6.A.2.c.2.i].
Encroachments: Certain architectural features of the accessory building, such as eaves, trim, and fascia boards, may encroach no more than 4 feet into a required yard, but they cannot be nearer than 5 feet to any property line unless they meet the specific 1-foot eave exception for standard accessory buildings [§3.2.6.A.3.a.3].
Basements and Subsurface Structures: Arlington County allows subsurface accessory structures to be located anywhere on a property, provided they do not interfere with public rights-of-way or air rights [§3.2.6.A.3.d].

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