Houston ADU rules at a glance
| Rule | What applies |
|---|---|
| Maximum size | Up to 1,500 sq ft for the second unit |
| Parking | None extra up to 1,000 sq ft; one extra space for 1,001–1,500 sq ft |
| Deed restrictions | Control. If they prohibit a second unit, you can’t build one |
| Fire separation | A fire-rated wall close to the line, or more distance from it, under the residential code |
| Floodplain | Elevation requirements apply on floodplain lots |
| Permits | Building and trade permits; a separate address if it has its own meter |
Steps to build one
- Get your recorded deed restrictions from the Harris County Clerk and read them.
- Check your flood zone and any utility easements.
- Decide on a new build, a garage apartment or converting a detached garage.
- Design with an engineer for foundation and wind loads.
- Apply for permits; the permit application includes a declaration that the project doesn’t violate deed restrictions.
Common questions
How big can an ADU be in Houston?
Up to 1,500 square feet for the second dwelling unit, under the Livable Places changes effective November 27, 2023, subject to your deed restrictions.
Can I rent out my ADU in Houston?
City rules don’t specifically ban it, but deed restrictions may. Short-term rentals also have their own city registration. Check both before you build.
How much does an ADU cost in Houston?
Remodeling’s 2025 Cost vs Value report puts an accessory dwelling unit in Houston at about $160,219. Converting an existing garage usually costs much less.
Sources
- Steadily: Houston ADU laws and regulations (Chapter 42, Ord. 2023-801)
- City of Houston Planning: Deed restrictions
- Remodeling Cost vs Value 2025: Houston
This guide is general information, not legal, tax or financial advice. Rules change; confirm details with the agency named in the sources or a licensed professional.