Arlington County R-20 One-Family Dwelling District Guide
The R-20 district in Arlington County is a low-density residential zone requiring a minimum lot area of 20,000 square feet and a minimum average lot width of 100 feet. Primarily intended for one-family detached dwellings, the district maintains a suburban character with a maximum building height of 35 feet and a base lot coverage limit of 25 percent.
Overview and General Character
The R-20 One-family Dwelling District is the lowest-density residential classification established in Arlington County. It is designed to preserve and protect one-family detached residential environments characterized by large parcels of land and significant open space. The general character of the R-20 district is defined by deep setbacks, substantial lot widths, and strict limits on building footprints to ensure the preservation of suburban aesthetics and natural landforms [§5.2, §3.2.1].
Permitted Land Uses
The Arlington County Zoning Ordinance permits a specific range of residential, institutional, and accessory uses within the R-20 district to maintain its low-density nature.
Principal Use Table
| Use Category | Specific Use Type | Permission Level | Use Standard |
|---|---|---|---|
| Household Living | One-family detached dwelling | Permitted (By-right) | §12.3.10 |
| Household Living | Recovery residence (8 or fewer residents) | Permitted (By-right) | §12.3.9 |
| Group Living | Group homes (licensed for adults) | Use Permit Required | §12.3.6 |
| Religious Institutions | Churches, mosques, synagogues, and temples | Permitted (By-right) | - |
| Schools | Schools (Elementary, middle, or high) | Use Permit Required | §12.4.1 |
| Agriculture | All agricultural uses | Permitted (By-right) | §12.7.1 |
| Telecommunications | Small cell or micro-wireless facilities | Permitted (By-right) | - |
Accessory and Temporary Uses
The R-20 district allows several accessory uses that are subordinate to the primary one-family dwelling:
- Accessory Dwellings: Allowed within or attached to the main dwelling or in a detached accessory building, subject to a limit of one per lot and specific footprint constraints [§12.9.2].
- Home Occupations: Includes professional services (e.g., accountant, architect, lawyer) and accessory homestays, provided they remain clearly incidental to the residential use [§12.9.11].
- Family Day Care Homes: Permitted for 1 to 12 children, provided they meet safety and neighborhood liaison requirements [§12.9.9].
- Private Swimming Pools: Permitted on the same lot as a one-family residence for use by occupants and guests [§12.9.17].
Density and Dimensional Standards
Arlington County enforces the following technical standards for all standard "by-right" development within the R-20 district.
Bulk and Coverage Requirements
| Standard Type | Requirement |
|---|---|
| Minimum Lot Area | 20,000 sq. ft. |
| Minimum Area per Dwelling Unit | 20,000 sq. ft. |
| Minimum Average Lot Width | 100 feet |
| Maximum Building Height | 35 feet |
| Maximum Lot Coverage (Base) | 25% |
| Max Main Building Footprint (Cap) | 4,480 sq. ft. |
| Max Footprint with Front Porch (Cap) | 5,320 sq. ft. |
Setback and Placement Standards
| Setback Type | Requirement |
|---|---|
| Street Setback (Front) | Minimum 25 feet from any street right-of-way line [§3.2.6.A.1] |
| Side Yard (Standard) | 10 feet (may be reduced to 8 feet on one side) [§3.2.6.A.2] |
| Side Yard (Aggregate) | Not less than 30% of the total lot width [§3.2.6.A.2] |
| Rear Yard (Main Building) | Minimum 25 feet from a rear lot line [§3.2.6.A.2] |
Special Development Options
The R-20 district is eligible for several specialized development types in Arlington County that allow for variations from standard dimensional requirements.
Expanded Housing Option (EHO)
Arlington County allows the development of duplexes, townhouses (up to 3 units), or multiple-family buildings (up to 6 units) in the R-20 district via a permit. These projects require a minimum site area of 20,000 square feet and a minimum lot width of 100 feet. The total main building gross floor area for these projects is capped based on the number of units (e.g., 8,000 sq. ft. for 5-6 units) [§10.4.4].
Unified Residential Development
For larger sites in the R-20 district, owners may apply for a Unified Residential Development. This requires a minimum site area of 40,000 square feet and a minimum frontage of 140 feet. This process allows the County Board to approve flexible, site-specific solutions for one-family detached dwellings [§10.1.2].
Residential Cluster Development
Residential cluster development may be approved in the R-20 district on sites of at least one acre but no more than two acres. This option allows the clustering of one-family, semidetached, or townhouse units to preserve natural landforms or historical features, provided the common open area per dwelling unit is at least 10,000 square feet [§10.3.2, §10.3.9].
Sections Cited
- Article 3. Density and Dimensional Standards
- §3.1. Measurements, Computations and Exceptions
- §3.2. Bulk, Coverage and Placement Requirements
- Article 5. Residential (R) Districts
- §5.1. Residential (R) Districts Use Tables
- §5.2. R-20, One-Family Dwelling District
- Article 10. Unified Developments
- §10.1. Unified Residential Developments
- §10.3. Residential Cluster Development
- §10.4. Expanded Housing Option Development
- Article 12. Use Standards
- §12.3. Residential Use Standards
- §12.9. Accessory Use Standards