ADU Rules in Austin, Texas

Overview

Austin is the state capital of Texas, home to the University of Texas at Austin, and one of the fastest-growing major cities in the United States. Travis County's population has grown explosively, driving a severe housing affordability crisis. In response, Austin has become one of Texas's most ADU-friendly cities, actively updating its Land Development Code (LDC) to permit more infill housing.

Texas has no statewide ADU preemption law — local zoning governs. Austin's Land Development Code is the primary regulatory document, and it has undergone significant changes through the HOME (Housing Options for Middle-Income Earners) initiative.

HOME Initiative: A Major Policy Shift

Austin's HOME initiative, approved by City Council beginning in 2023, represents one of the most significant zoning changes in Austin's history. Key provisions affecting ADUs and residential density include:

• Three units allowed by right on lots previously restricted to single-family use citywide
• This means a primary house plus two ADUs (or three units in any configuration) is generally permitted in SF districts
• Compatibility standards loosened: The previous compatibility overlay (which reduced allowed building heights and massing near single-family homes) was significantly relaxed for smaller-scale infill
• Minimum lot size reduced: Smaller lots can now support development that was previously restricted

HOME phases are being implemented over time. Confirm which HOME provisions are currently in effect with the Development Services Department.

Zoning Districts and ADU Rules

Austin's primary single-family residential district is SF-3 (Family Residence), which covers much of the city. ADU rules in SF-3 and comparable districts:

• Detached ADUs (DADUs): Allowed in SF-3; standard maximum size is 1,100 sq ft (larger may be permitted based on lot size)
• Attached ADUs: Secondary suites attached to the primary dwelling; generally allowed up to a higher percentage of primary dwelling floor area
• Garage apartments: Permitted as a form of DADU; popular in Austin
• ADUs on alley lots: Austin has many alley-served properties where rear ADUs are common and practical

Development Standards

Typical ADU standards in Austin's SF-3 and similar districts:

• Maximum size: 1,100 sq ft for standard DADUs; verify for your specific lot size and district
• Height: Limited to the lesser of 16 ft (to top of plate) or two stories; two-story DADUs require additional setbacks
• Rear setback: 5 ft from rear property line
• Side setback: 5 ft from side property line
• Impervious cover: Maximum 45% of lot area for residential lots (includes all paved surfaces and structures)
• Parking: As of recent LDC amendments, minimum parking requirements have been reduced in many areas; verify current requirements

Flood Risk: Colorado River and Barton Creek

Austin is situated on the Colorado River (Lady Bird Lake, Lake Austin) and Barton Creek, with significant portions of the city in FEMA flood hazard areas. Barton Creek in particular experiences severe flash flooding during heavy rain events. Properties in floodplains require a floodplain development permit from the City of Austin Watershed Protection Department, and new structures must meet elevation requirements. Austin's 100-year and 25-year floodplain maps are available at austintexas.gov/watershed.

Historic Districts and Historic Landmarks

Austin has designated historic districts (Clarksville, Willow-Spence Streets, Hyde Park, and others) and many individual historic landmarks. New construction in these areas, including ADUs, typically requires review by the Historic Landmark Commission. Design compatibility standards apply.

Permit Process

1. Look up your zoning district and applicable overlays at austintexas.gov/gis or the Austin Build + Connect portal
2. Verify HOME initiative applicability for your address
3. Check impervious cover, floodplain, and historic overlay status
4. Submit permit application through Austin Build + Connect (abc.austintexas.gov)
5. Plan review for zoning, building code, fire, drainage
6. Inspections at foundation, framing, and final through certificate of occupancy

Contact

• Austin Development Services Department: austintexas.gov/DSD | 512-978-4000
• Austin Build + Connect (permits): abc.austintexas.gov
• Watershed Protection Department: austintexas.gov/watershed
• Historic Landmark Commission: austintexas.gov/hlc

Disclaimer: Austin's Land Development Code, including HOME initiative provisions, has been actively changing. This page reflects general guidance as of the date noted. Always verify current ADU rules with the City of Austin Development Services Department and a licensed Texas professional before proceeding.