Accessory Dwelling Unit (ADU) Size and Regulation Guide for Fort Worth
In the City of Fort Worth, a habitable accessory structure, such as an accessory dwelling unit (ADU), is permitted as long as its total square footage does not exceed the square footage of the primary structure [Section 5.300]. These units are strictly reserved for non-rental use by family members or temporary guests and are prohibited from containing cooking equipment [Section 9.101].
Maximum Square Footage for Habitable Accessory Buildings
The City of Fort Worth zoning code establishes a clear ceiling for the size of any habitable accessory building. According to the general standards for accessory uses, an accessory structure shall not be a greater square footage than the primary structure located on the same lot [Section 5.300]. While the City of Fort Worth provides a tiered table of maximum square footages for non-habitable structures (such as sheds or workshops), habitable structures like ADUs are governed by their relationship to the size of the principal residence [Section 5.301].
Definition and Usage Restrictions
The City of Fort Worth defines an "Accessory Dwelling Unit" with specific limitations regarding who may occupy the space and what equipment may be installed.
Use and Occupancy
An ADU in the City of Fort Worth is intended for the occupancy of a member of the family residing in the main house or for temporary guests. The City of Fort Worth expressly prohibits these units from being rented or leased to outside parties [Section 9.101]. Furthermore, in one-family districts, an ADU may not be used as a separate independent residence [Section 5.301].
Prohibited Equipment
A critical distinction in the City of Fort Worth zoning ordinance is that an accessory dwelling unit must not contain cooking equipment [Section 9.101]. If a subordinate building contains facilities for living, sleeping, and eating but is used for purposes other than a non-rented guest or family suite, it may fall under different regulatory categories.
ADU Development Standards
The City of Fort Worth mandates that habitable accessory structures meet the following technical requirements:
| Standard | Requirement |
|---|---|
| Maximum Size | Must not exceed the square footage of the primary structure [Section 5.300] |
| Maximum Height | Must not exceed the height of the primary structure [Section 5.301] |
| Setbacks | Must comply with side and rear setbacks required for the primary structure in that specific district [Section 5.301] |
| Utility Meters | Must receive water, electric, and gas service from the meters serving the primary structure [Section 5.300] |
| Building Code | Must meet all applicable City of Fort Worth building codes for habitable structures [Section 5.301] |
Placement and Visual Integration
The City of Fort Worth requires that accessory structures be secondary to the primary use of the property. They cannot be constructed or placed on a lot without a primary use already established [Section 5.300].
In the City of Fort Worth, accessory structures are generally prohibited in front yards. No attached or detached accessory structure may be erected within a minimum front yard, established front yard, or projected front yard [Section 5.300]. Additionally, any accessory structure attached to the primary residence by a breezeway or covered walkway is not considered an extension of the primary structure for the purposes of these regulations [Section 5.301].
Comparison: Non-Habitable Accessory Structures
While habitable ADUs are limited by the size of the primary house, the City of Fort Worth applies different cumulative square footage caps to non-habitable structures (such as detached porches, greenhouses, and storage sheds) based on the total size of the residential lot.
| Lot Size in the City of Fort Worth | Maximum Total Square Feet for Non-Habitable Accessory Buildings |
|---|---|
| Less than 5,000 square feet | 120 square feet |
| 5,000 to 9,999 square feet | 200 square feet |
| 10,000 to 21,779 square feet | 400 square feet |
| 21,780 to 43,559 square feet | 400 square feet |
| 43,560 square feet or larger | 2% of the total area of the lot |
Note: These limits are cumulative for all non-habitable structures but do not include private garages or carports [Section 5.301].
Sections Cited
- Section 4.713 Urban Residential (UR) District
- Section 5.300 Accessory Uses, General
- Section 5.301 Accessory Uses on Residential Lots
- Section 9.101 Defined Terms