Setback Requirements for the R-10 One-Family Dwelling District in Arlington County
Residential structures within the R-10 One-family Dwelling district in Arlington County must generally maintain a front setback of at least 25 feet from the street right-of-way and a rear yard of at least 25 feet for interior lots. Side yards in the R-10 district are required to be at least 10 feet wide, though one side may be reduced to 8 feet as long as the combined width of both side yards equals at least 30 percent of the total lot width.
Density and Dimensional Overview for R-10
The Arlington County Zoning Ordinance establishes the R-10 district to provide for one-family dwellings with specific requirements for lot size and building placement. In this district, the minimum average lot width is set at 80 feet, and the minimum lot area is 10,000 square feet [§5.3.3]. These dimensions directly influence the calculation of required side yard aggregates.
| Setback Type | Minimum Requirement for R-10 District |
|---|---|
| Front Yard | 25 feet from street right-of-way line |
| Side Yard (Single) | 10 feet (One side may be reduced to 8 feet) |
| Aggregate Side Yards | 30% of the required lot width |
| Rear Yard | 25 feet (on interior lots) |
Front Setback Standards
The primary front yard requirement for one-family dwellings in Arlington County is 25 feet from any street right-of-way line. However, the Arlington County Zoning Ordinance provides for several modifications and limitations to this standard [§3.2.6.A.1(e)]:
- Averaging Exception: The required distance between the street right-of-way and the front wall of a structure may be reduced to the average of the distances of existing structures located on the same frontage. This reduction cannot result in a setback of less than 15 feet from the right-of-way line [§3.2.6.A.1(e)(1)].
- Parking Garages: Regardless of averaging, no parking garage within the R-10 district may be located closer than 18 feet from the street right-of-way line [§3.2.6.A.1(e)(2)].
- Height Limitation: Any portion of a structure located within 25 feet of a street right-of-way line is restricted to a maximum height of 2.5 stories [§3.2.6.A.1(e)(3)].
Side and Rear Yard Standards
The R-10 One-family Dwelling district requires specific spacing between structures and property lines to ensure privacy and adequate light and air [§3.2.1].
Side Yard Specifications
Individual side yards for one-family dwellings in Arlington County must be 10 feet. A single side yard may be reduced to 8 feet, provided the "aggregate width" (the sum of both side yards) is not less than 30 percent of the required lot width [§3.2.6.A.2(b)]. For a standard R-10 lot with the required 80-foot width, the aggregate side yard requirement would be 24 feet.
Rear Yard Specifications
For interior lots in the R-10 district, no structure may be located closer than 25 feet from a rear lot line [§3.2.6.A.2(b)].
Permitted Encroachments
Arlington County allows certain architectural and functional features to project into the required yards of the R-10 One-family Dwelling district [§3.2.6.A.3]:
- Architectural Features: Bay and oriel windows (without floor space) and chimneys may encroach up to 18 inches into required yards [§3.2.6.A.3(a)(1)].
- Unenclosed Features: Balconies, eaves, decks, patios (8 inches or higher above grade), and stoops may encroach up to four feet into required yards, provided they remain at least five feet from any property line [§3.2.6.A.3(a)(3)].
- Porches: On interior lots, porches may encroach four feet into required front and rear yards, but must remain at least 21 feet from the street right-of-way line [§3.2.6.A.3(a)(4)].
- Steps and Stairs: These may encroach into required yards provided they are no closer than five feet to any lot line. Stairs wider than 35 percent of the building elevation or those less than 8 inches above finished grade have different specific allowances [§3.2.6.A.3(a)(6)].
- Mechanical Equipment: Air conditioning units and similar mechanical equipment are permitted in side and rear yards, provided they are at least eight feet from any side lot line and 10 feet from any rear lot line [§3.2.6.A.3(b)].
Sections Cited
- Article 3. Density and Dimensional Standards
- §3.1.9. Setbacks and yards
- §3.2.1. Purpose
- §3.2.6. Placement
- Article 5. Residential (R) Districts
- §5.3. R-10, One-Family Dwelling District