Texas has no statewide ADU law. Every city sets its own rules, and those rules vary enormously — from Austin's aggressive reform push to suburban municipalities that effectively prohibit accessory dwelling units through lot size minimums and impervious cover limits. If you're evaluating an ADU play in Texas, you need to research the specific city's code, not the state's.
Why There Is No Texas ADU Law
Texas has a strong tradition of local control over land use. The state legislature has generally declined to preempt municipal zoning decisions the way California and Massachusetts have done. That means Texas cities face no state floor requiring them to allow ADUs, permit them by right, or limit the conditions they can impose. A handful of state preemption bills have been introduced in the Texas legislature, but as of 2025 none have passed. Investors in Texas must treat each city as its own jurisdiction.
Austin: The Most ADU-Friendly Major City in Texas
Austin has made ADU reform a deliberate policy priority. The HOME (Home Options for Middle-income Empowerment) initiative, adopted in phases starting in 2023, is the most significant local zoning change in Austin in decades. HOME Phase 1 eliminated single-family-only zoning citywide, allowing up to three dwelling units on any lot that was previously zoned for single-family use. HOME Phase 2, adopted in 2024, reduced minimum lot sizes, eliminated parking minimums in many areas, and removed the floor area ratio limits that had been a practical barrier to adding square footage.
Under Austin's current rules, most standard lots can support a detached ADU without a variance. The primary constraints are setbacks (typically 5 feet from the rear and side property lines for an ADU), impervious cover limits (varies by zone, typically 45–55% of lot area), and maximum unit size (the lesser of 1,100 square feet or 15% of the lot area in some zones). Austin does not require owner-occupancy and does not require off-street parking for ADUs in most of its urban core.
Houston: No Zoning, But Real Constraints Exist
Houston is famously the largest city in the United States without traditional zoning. But "no zoning" does not mean no rules. Houston regulates land use through deed restrictions, minimum lot size ordinances, and building setback requirements, all of which affect ADU feasibility.
Houston's minimum lot size ordinance historically required 5,000 square feet per single-family dwelling unit, which effectively blocked ADUs on standard urban lots. The city has made incremental reforms, and the minimum lot size for some urban areas has been reduced. However, many older subdivisions in Houston carry private deed restrictions that are enforced by homeowners' associations or neighboring property owners — not the city — and those restrictions may prohibit secondary structures, require minimum square footage for all dwellings, or limit rental use. Deed restriction searches are essential due diligence in Houston before any ADU project.
Dallas: Incremental Progress
Dallas has been slower to reform than Austin. Dallas's zoning code uses a family of residential districts (R-1 through R-10 and higher-density designations) with varying rules for accessory structures and secondary dwelling units. Most single-family districts in Dallas historically allowed garage apartments or carriage houses as accessory uses but imposed owner-occupancy requirements and square footage caps that limited their usefulness as investment units.
Dallas adopted a new ForwardDallas comprehensive plan in 2024 that signals greater openness to missing-middle housing and ADUs. Implementation through zoning code changes is ongoing. As of 2025, Dallas remains a city where ADU rights depend heavily on the specific zoning district and where the code has not yet been comprehensively reformed to remove historic barriers. Check the Dallas Development Code directly for the specific district designation on any parcel.
San Antonio: Still Restrictive in Most Districts
San Antonio's Unified Development Code allows secondary dwelling units in some residential districts, but the rules are among the more restrictive of the major Texas cities. Owner-occupancy is required in most districts that allow ADUs. The secondary unit is typically capped at 50% of the floor area of the primary dwelling or a fixed square footage maximum (often around 850 square feet), whichever is smaller. Parking requirements apply in most non-transit-adjacent areas.
San Antonio has discussed ADU reform in its SA Tomorrow comprehensive plan, but major code changes have not yet materialized. Investors in San Antonio should expect to encounter owner-occupancy requirements and should verify the specific district rules before assuming an ADU is a viable exit strategy.
What Commonly Blocks Texas ADUs
Across Texas cities, the most common barriers to ADU development are:
- Impervious cover limits: Adding a detached ADU adds hard surface. Many lots are already at or near their impervious cover cap, making a detached unit impossible without also reducing driveway or patio coverage.
- Owner-occupancy requirements: Outside Austin, most Texas cities still require the owner to reside on the property. This is the single most common barrier for investor-owned properties.
- Deed restrictions: Private deed restrictions, especially in Houston and older suburban subdivisions, frequently prohibit secondary structures or rental units. These are enforceable by neighbors, not just the city, and are not affected by municipal ADU reform.
- Lot size minimums: Some cities require a minimum lot area before a secondary unit is allowed, often in the range of 6,000–8,000 square feet.
- Utility capacity: In areas with older infrastructure, water and sewer capacity for a second unit may trigger expensive upgrades.
How to Check Local Rules in Texas
Texas does not have a centralized state portal for local zoning rules. Each city maintains its own code. The most reliable approach is:
- Identify the zoning district designation for the specific parcel using the city's online GIS map or property records portal.
- Pull the relevant section of the city's unified development code or zoning ordinance — most Texas cities publish these on Municode or their own planning department website.
- Search the code for "accessory dwelling unit," "secondary dwelling unit," "garage apartment," and "backyard cottage" — different cities use different terms.
- In Houston, run a deed restriction search through the Harris County Appraisal District or a title company before relying on the absence of municipal zoning to conclude that an ADU is permissible.
- Call the city's planning or development services department to confirm your reading. Texas planning staff are generally accessible and will answer basic questions about whether a proposed use is allowed.