Accessory Dwelling Units and Secondary Living Units in the City of Arlington
In the City of Arlington, accessory residential units are primarily classified as "Secondary Living Units" or "Garage Apartments," with permissions varying significantly based on the specific zoning district. Secondary living units are strictly limited to occupancy by family members or relatives and are legally prohibited from being rented or leased to third parties. While secondary living units are allowed by right or by Specific Use Permit in most low-to-medium density residential districts, garage apartments are generally permitted in higher-density residential and mixed-use districts, where they are factored into the total allowed dwelling unit density for the site.
Authorized Zoning Districts
The City of Arlington UDC identifies specific districts where accessory dwelling types are permitted. These are categorized into units that function as separate structures or additions (Secondary Living Units) and those integrated into garages (Garage Apartments).
Permissions by District
| Zoning District Type | Secondary Living Unit | Garage Apartment |
|---|---|---|
| Residential Estate (RE) | Permitted (P*) | Prohibited |
| Residential Single-Family 20 (RS-20) | Permitted (P*) | Prohibited |
| Residential Single-Family 15 (RS-15) | Permitted (P*) | Prohibited |
| Residential Single-Family 7.2 (RS-7.2) | Specific Use Permit (S*) | Prohibited |
| Residential Single-Family 5 (RS-5) | Specific Use Permit (S*) | Prohibited |
| Residential Medium-Density 12 (RM-12) | Specific Use Permit (S*) | Permitted (P*) |
| Residential Multi-Family 22 (RMF-22) | Prohibited | Permitted (P*) |
| Village on the Green (VG) | Permitted (P*) | Prohibited |
| Downtown Business (DB) | Prohibited | Permitted (P) |
| Neighborhood Mixed-Use (NMU) | Prohibited | Permitted (P) |
| Regional Mixed-Use (RMU) | Prohibited | Permitted (P) |
*Subject to supplemental use standards. [Section 3.3.4, Table 3.3-1 and Table 3.3-2]
Standards for Secondary Living Units
A Secondary Living Unit is defined by the City of Arlington as a second single-family residential unit located on the same lot as a primary unit, providing independent provisions for living, sleeping, cooking, and sanitation [Section 12.7.1].
Use and Occupancy Restrictions
- Family Only: The unit is reserved exclusively for use by family members or relatives of the occupants of the primary residence [Section 12.7.1].
- Leasing Prohibited: The City of Arlington expressly prohibits these units from being rented or leased [Section 12.3.5.N].
- Unit Size: The structure is limited to a maximum of one bedroom, one kitchen, and one bathroom [Section 3.3.6.L.2].
- Quantity: Only one secondary living unit is allowed per lot [Section 3.3.6.L.3].
Development Standards
Secondary living units must comply with the same standards as the primary structure, with specific exceptions for certain requirements.
| Standard | Requirement |
|---|---|
| Setbacks | Must meet all standards applied to the primary structure [Section 3.3.6.L.1]. |
| Parking | Exempt from standard off-street parking requirements [Section 3.3.6.L.1]. |
| Max Height | Limited to a maximum of 24 feet [Section 3.3.5.D]. |
| Lot Coverage | Total floor area of any detached accessory structure (including the unit) shall not exceed 50% of the floor area of the principal structure [Section 3.3.5.A.3]. |
[Section 3.3.5 and Section 3.3.6.L]
Standards for Garage Apartments
A Garage Apartment is a dwelling unit designed or constructed as part of a private garage [Section 12.3.5.H].
Density and Parking
In the City of Arlington, garage apartments are treated more like standard dwelling units than traditional accessory structures in several districts:
- Density Calculations: In the RM-12, RMF-22, DB, NMU, and RMU districts, a garage apartment is counted as a full dwelling unit for the purposes of calculating the allowed density on the site [Section 3.3.6.F].
- Parking Requirement: The City of Arlington requires one off-street parking space per garage apartment dwelling unit [Section 5.4.3, Table 5.4-1].
General Accessory Building Limits
Any secondary unit or garage apartment that is detached from the primary residence must adhere to the City of Arlington's limits on the total number of accessory buildings permitted per lot.
| Lot Size | Maximum Number of Accessory Buildings |
|---|---|
| Less than 1 acre | 3 buildings |
| 1 acre and larger | 5 buildings |
[Section 3.3.6.C, Table 3.3-4]
Sections Cited
- Section 3.3.4 (Use Tables for Accessory Uses and Structures)
- Section 3.3.5 (General Standards for All Accessory Uses and Structures)
- Section 3.3.6 (Supplemental Accessory Use Standards)
- Section 5.4.3 (Off-Street Parking Standards)
- Section 12.3.5 (Accessory Uses and Structures Definitions)
- Section 12.7.1 (Other Terms Defined)