Setback Requirements for the C-O-2.5 Mixed Use District in Arlington County

In the Arlington County C-O-2.5 Mixed Use District, the standard front setback for most structures is 40 feet from the street centerline. Side and rear setbacks are generally not required (0 feet) for commercial and mixed-use buildings, unless the structure abuts a residential district or contains windows, in which case a depth determined by the building's height must be maintained. For one-family detached dwellings within the Arlington County C-O-2.5 District, the front setback is 25 feet from the street right-of-way line.

Front Setback Requirements

The placement of buildings in the Arlington County C-O-2.5 District is governed by the general standards for Commercial (C) districts. The requirement varies depending on the type of structure and its proximity to the street.

Structure Type	Required Front Setback	Citation
Commercial & Mixed-Use Buildings	40 feet from the street centerline	[§3.2.6.A.1(a)]
One-Family Detached Dwellings	25 feet from the street right-of-way line*	[§3.2.6.A.1(e)]

*This distance may be reduced to the average setback of existing structures on the same frontage, but under no circumstances less than 15 feet (or 18 feet for a parking garage) [§3.2.6.A.1(e)].

Side and Rear Setback Requirements

Under the Arlington County Zoning Ordinance, the C-O-2.5 District does not have a mandatory minimum side or rear yard for commercial or mixed-use structures under typical conditions. However, "transitional" setbacks are triggered by specific site conditions or architectural features.

Commercial and Mixed-Use Structures

For most non-residential or mixed-use developments in the Arlington County C-O-2.5 District, the side and rear setbacks are 0 feet, except in the following cases:

Abutting Residential Districts: If a wall abuts an R or RA district, a setback is required.
Walls with Openings: If a wall contains windows or openings (whether or not they can be opened), a setback must be provided.

In these specific instances, the setback depth is calculated based on the building's height:

Initial Setback: 8 feet for the first 10 feet of building height.
Incremental Increase: An additional 2 feet of setback for every 10 feet of additional building height (or fraction thereof) beyond the first 10 feet [§3.2.6.A.2(a)].

One-Family Detached Dwellings

If a one-family detached dwelling is established in the Arlington County C-O-2.5 District, it must follow residential placement standards:

Side Yard: 10 feet. One side may be reduced to 8 feet, but the aggregate width of both side yards must be at least 30% of the total lot width [§3.2.6.A.2(b)].
Rear Yard: 25 feet for interior lots [§3.2.6.A.2(b)].

Modifications via Site Plan Approval

The Arlington County C-O-2.5 District frequently involves large-scale developments that require special exception site plan approval. In these cases, the County Board has the authority to modify standard setback and yard requirements to achieve better urban design or to fulfill the goals of the Arlington County Comprehensive Plan [§15.5.7.A]. Any such modifications must be expressly approved as part of the site plan conditions.

Sections Cited