Residential Building Height Standards in Arlington County
In Arlington County, the maximum allowable height for a one-family residential house is typically 35 feet across all standard residential (R) zoning districts. While this 35-foot limit is the general rule for by-right development, certain conditions—such as building on a lot of 100 acres or more or developing specialized townhouse projects in the R15-30T district—may allow for heights to reach 45 or 55 feet via a use permit or special exception.
General Height Limits by Zoning District
The Arlington County Zoning Ordinance establishes specific height limits based on the classification of the property. For a standard one-family detached house, the following limits apply:
| Zoning District Name | Maximum Height (By-Right) | Special Exception/Use Permit Max |
|---|---|---|
| R-20 (One-Family Dwelling District) | 35 feet | 55 feet (on lots of 100+ acres) |
| R-10 (One-Family Dwelling District) | 35 feet | 55 feet (on lots of 100+ acres) |
| R-8 (One-Family Dwelling District) | 35 feet | 55 feet (on lots of 100+ acres) |
| R-6 (One-Family Dwelling District) | 35 feet | 55 feet (on lots of 100+ acres) |
| R-5 (One-Family Dwelling District) | 35 feet | 55 feet (on lots of 100+ acres) |
| R2-7 (Two-Family and Townhouse District) | 35 feet | 55 feet (on lots of 100+ acres) |
| R-10T (One-Family and Townhouse District) | 35 feet | 36 feet (for townhouse projects) |
| R15-30T (Townhouse Dwelling District) | 35 feet | 45 feet (for townhouse projects) |
[§4.2.3, §5.2.3, §5.3.3, §5.4.3, §5.5.3, §5.6.3, §5.7.3, §5.8.3, §5.9.3]
Measurement Methodology in Arlington County
To determine if a residential house complies with Arlington County standards, the height is measured as the vertical distance from the average existing grade to a specific point on the roof, depending on the roof style:
- Flat Roofs: Measured to the highest point of the roof surface or coping [§3.1.6.A].
- Mansard Roofs: Measured to the deck line of the roof [§3.1.6.A].
- Gable, Hip, or Gambrel Roofs: Measured to the mean height level (the midpoint) between the eaves and the highest ridge point [§3.1.6.A].
- Nuance for Dormers: If a dormer exceeds 50 percent of the horizontal width of the roof on one side, that dormer roof is considered the main roof for that side of the building. In this scenario, the building height is measured to the midpoint between the eaves and the ridge of the dormer roof [§3.1.6.A].
Calculation of Grade
In all Residential (R) districts (excluding RA apartment districts), Arlington County requires the average existing grade to be calculated by averaging the grade at four specific points at the perimeter of the building. These points must include two points on the front and two points on the rear, specifically those closest to the applicable side lot lines [§3.1.6.A.1].
Height Exceptions and Restrictions
Large Lot Use Permits
The Arlington County Board may approve a use permit to increase the height of a single main building to 50 or 55 feet on residential lots that are 100 acres or larger. In these cases, the building must be set back at least 150 feet from all lot lines and public rights-of-way [§5.2.3.C].
Setback-Related Limitations
Arlington County imposes a story-based restriction on houses located near the street. No structure situated within 25 feet of a street right-of-way line may exceed 2 ½ stories in height [§3.2.6.A.1(e)(3)].
Appurtenances
Certain architectural and functional features are permitted to exceed the standard height limits in Arlington County:
- Mechanical penthouses and steeples: May exceed the limit but cannot be used for additional floor space and may not exceed 23 feet above the limit [§3.1.6.B.1].
- Chimneys and smokestacks: If integrated into a mechanical penthouse, these may exceed the height limit by up to 27 feet [§3.1.6.B.3].
- Amateur radio antennas: Generally limited to 75 feet in height from the ground level [§3.1.6.B.5].
Sections Cited
- §1.7.1 General Districts
- §3.1.6 Height
- §3.2.6.A.1 Setbacks from any street
- §4.2.3 S-3A Density and dimensional standards
- §5.2.3 R-20 Density and dimensional standards
- §5.3.3 R-10 Density and dimensional standards
- §5.4.3 R-10T Density and dimensional standards
- §5.5.3 R-8 Density and dimensional standards
- §5.6.3 R-6 Density and dimensional standards
- §5.7.3 R-5 Density and dimensional standards
- §5.8.3 R15-30T Density and dimensional standards
- §5.9.3 R2-7 Density and dimensional standards
- §10.4.4 Expanded Housing Option Density and dimensional standards