Accessory Dwelling Unit (ADU) Floor Area Regulations in the City of Dallas
In the City of Dallas, the maximum floor area permitted for an Accessory Dwelling Unit (ADU) is generally the greater of 700 square feet or 25 percent of the main structure or use [Sec. 51A-4.510]. Detached ADUs must also meet a minimum size requirement of 200 square feet.
Floor Area Requirements for City of Dallas ADUs
The City of Dallas defines an Accessory Dwelling Unit as a rentable additional dwelling unit that is subordinate to a main unit on a single-family building site. Within an Accessory Dwelling Unit Overlay, specific floor area standards apply based on whether the unit is attached to the primary home or detached as a separate structure [Sec. 51A-4.510].
Maximum and Minimum Size Standards
| ADU Type | Minimum Floor Area | Maximum Floor Area |
|---|---|---|
| Detached ADU | 200 square feet | The greater of 700 square feet or 25% of the main structure |
| Attached ADU | No minimum specified | The greater of 700 square feet or 25% of the main use |
Additional Placement and Design Regulations
Beyond the raw square footage, the City of Dallas regulates the height and location of ADUs to ensure they remain subordinate to the primary residence.
Height Restrictions
The maximum height of an Accessory Dwelling Unit in the City of Dallas cannot exceed the height of the main dwelling unit [Sec. 51A-4.510]. However, for units located above a detached garage, the maximum height allowed is determined by the specific zoning overlay.
Setbacks and Location
Specific setbacks apply if the structure containing the City of Dallas ADU is less than 15 feet in height and situated in the rear 30 percent of the lot. In these instances, the minimum side and rear setbacks are reduced to three feet. If the structure is 15 feet or taller, it must comply with the standard side and rear yard setbacks of the base zoning district [Sec. 51A-4.510]. Furthermore, an ADU may not be located in front of the main structure on the lot.
Parking Requirements
The City of Dallas requires a minimum of one off-street parking space for an Accessory Dwelling Unit. This requirement is waived if the building site is located within 1,200 feet of a DART bus or transit stop. Additionally, the required parking may be reduced if 75 percent of the property owners within a proposed overlay sign a petition agreeing to the reduction [Sec. 51A-4.510].
Sections Cited
- Sec. 51A-4.510 Accessory Dwelling Unit Overlay
- Sec. 51A-2.102 Definitions
- Sec. 51A-4.704 Nonconforming Uses and Structures
- Sec. 51A-4.209 Residential Uses