Texas ADU Rules, City by City: Austin, Dallas, Houston, San Antonio

Why Texas ADU rules are a patchwork

Unlike some states, Texas has no statewide ADU mandate. No state law forces cities to allow accessory dwelling units, standardizes size limits, or overrides local parking rules. Every city writes its own ordinance, which is why the same 750 sq ft backyard unit can be a straightforward by-right project in one metro and an uphill exception process in the next.

The legislature came close to changing that. Senate Bill 673, filed in the 2025 session, would have preempted many local ADU restrictions statewide. It died in the House on June 2, 2025. Until a similar bill passes, city ordinances control, and those ordinances get amended regularly. Treat everything below as a planning starting point and confirm current requirements with your local permitting office before you finalize drawings, because details like setbacks, height limits, and utility connections vary by jurisdiction and change over time.

If you are weighing Texas against other markets, our companion guide to ADU laws in Texas, Florida, New York, and California covers the bigger state-by-state picture.

Austin: the most permissive big city in Texas

Austin rewrote its single-family zoning through the HOME Initiative, adopted in two phases: Phase 1 in December 2023 and Phase 2 in May 2024. Together, the reforms cut the minimum lot size to 2,500 sq ft, allow up to three units on a single-family lot, and removed both off-street parking requirements and the owner-occupancy requirement that previously shaped who could build and rent an ADU.

The market responded quickly. Austin issued more than 1,200 ADU permits in the two years following the reforms, a 340% increase. That volume also means Austin reviewers see a lot of ADU submittals, so clean, complete plan sets tend to move through review with fewer correction cycles.

Dallas: overlay districts and tighter caps

Dallas takes nearly the opposite approach. ADUs are not permitted citywide by default. To build one, your property generally needs to sit inside an ADU Overlay District (ADUO), which requires an area of 50 or more contiguous single-family structures to opt in together, or you need an exception from the Board of Adjustment. Before any design work starts, the first question in Dallas is simply whether your block qualifies.

Even where ADUs are allowed, the constraints are tight. Units are capped at 800 sq ft, owner occupancy is tied to one of the units on the property, and rented ADUs carry an annual rental registration requirement.

Houston: no zoning, but deed restrictions rule

Houston famously has no zoning code, which leads many owners to assume anything goes. It does not. The city ordinance sets a 900 sq ft cap for ADUs, requires 5 ft setbacks, and requires one off-street parking space.

The bigger trap is private law. Large parts of Houston are governed by deed restrictions recorded against the property, and those restrictions can prohibit second dwellings outright or impose limits stricter than the ordinance. Because they can override everything the city otherwise allows, deed verification is step one on any Houston ADU project. Pull the recorded restrictions for your subdivision before you spend money on design.

San Antonio: by-right approval, with strings attached

San Antonio allows ADUs by right in many residential districts, provided the owner signs an owner-occupancy affidavit. Size is capped at the lesser of 50% of the primary home's size or roughly 1,000 to 1,200 sq ft, and an off-street parking space is required only when the ADU exceeds 800 sq ft.

That 50% rule matters more than it looks. On a 1,400 sq ft primary home, the ADU tops out at 700 sq ft, well under the headline cap. Smaller homes get smaller ADUs, so the primary structure's size should be one of the first numbers you check.

Austin vs Dallas vs Houston vs San Antonio at a glance

Houston also requires 5 ft setbacks under its ordinance. Setback, height, and utility rules in the other cities vary by district and lot, so verify them with your local reviewer before finalizing a site plan.

What this means for your ADU design

1. Verify jurisdiction and deed restrictions first. Confirm which city (or county) you are in, whether an overlay applies, and, especially in Houston, what your recorded deed restrictions say. This one step prevents most wasted design fees.
2. Design to the cap, not past it. A plan drawn at 850 sq ft is unbuildable in Dallas and triggers parking in San Antonio. Knowing the cap before schematic design keeps you out of redesign loops.
3. Put parking and setbacks on the site plan early. Where a space is required, its location drives the driveway, the ADU entry, and often the whole backyard layout. Solving it on paper is far cheaper than solving it in review comments.
4. Choose the right drafting path. A proven layout that already fits your city's limits saves time and money; an unusual lot, a strict deed restriction, or a tight 50% calculation usually calls for custom work.

Whichever path you choose, the final deliverable should be a complete, reviewer-friendly set. Our permit-ready drawings and as-builts are prepared for local submittal requirements, and we coordinate revisions if your reviewer requests changes.

Frequently asked questions