C-O-1.5: Mixed Use District Setback Requirements in Arlington County

In Arlington County, the C-O-1.5: Mixed Use district requires a minimum front setback of 40 feet from the street centerline, while also maintaining a distance of at least 50 percent of the total building height from that centerline. No side or rear yards are required for the C-O-1.5: Mixed Use district unless the property abuts a residential (R or RA) district or contains wall openings, at which point a specific sliding-scale buffer must be implemented based on the height of the structure. Furthermore, large-scale developments within the C-O-1.5: Mixed Use district that exceed 12 stories (for residential/hotel) or 8 stories (for offices) must be set back at least 200 feet from any residential district with a lower height limit.

Street (Front) Setback Requirements

The primary placement rule for the C-O-1.5: Mixed Use district in Arlington County is determined by the relationship between the building height and the street centerline. Per the general placement standards, no structure may be closer to the centerline of any street or officially designated street right-of-way than 50 percent of the height of the building [§3.2.6.A.1]. Additionally, specific minimums apply based on the district classification.

Setback Type	Minimum Requirement	Calculation/Standard
Minimum Street Setback	40 feet	Measured from the centerline of any street [§3.2.6.A.1(a)]
Height-Based Street Setback	50% of Building Height	Measured from the centerline of the street [§3.2.6.A.1]

Side and Rear Yard Requirements

For most commercial developments in the C-O-1.5: Mixed Use district, there is no inherent requirement for a side or rear yard. However, Arlington County mandates setbacks if the building design includes windows/openings or if the lot is adjacent to residential zones [§3.2.6.A.2(a)].

Standard Side and Rear Yards

General Rule: No side or rear yard is required for the C-O-1.5: Mixed Use district [§3.2.6.A.2(a)].
Exception for Openings: If a wall contains openings or windows (regardless of whether they can be opened), a setback is required [§3.2.6.A.2(a)].
Exception for Residential Adjacency: If a lot in the C-O-1.5: Mixed Use district abuts an R or RA district, a setback is required [§3.2.6.A.2(a)].

Buffer Calculation for Exceptions

When the exceptions noted above are triggered, the side or rear yard depth in the C-O-1.5: Mixed Use district is calculated using the following sliding scale:

Building Height	Required Setback
First 10 feet of height	8 feet
Each additional 10 feet of height	+2 feet (or fraction thereof)

Locational Setbacks for Large Projects

For large sites (20 acres or larger) within the C-O-1.5: Mixed Use district, Arlington County imposes additional locational setbacks to protect lower-density neighborhoods. Buildings that exceed specific story counts cannot be placed in close proximity to certain residential areas.

Office Buildings: If the building exceeds eight stories, it must be located at least 200 feet from a residential district with a lower height limit [§7.11.3.D.2].
Multiple-family or Hotels: If the building exceeds 12 stories, it must be located at least 200 feet from a residential district with a lower height limit [§7.11.3.D.2].

Sections Cited