Development Regulations
Building in Unincorporated Travis County: Chapter 482 Rules
If you subdivide or develop land outside any city in Travis County, state and county development rules apply.
Want to subdivide or develop land outside any city in Travis County? You must follow the county's rules under Chapter 482. These rules cover drainage, water quality easements, street standards, and building permits.
Land near the Edwards Aquifer recharge zone has extra limits. The aquifer supplies drinking water for the region. Because of that, the county limits how much hard surface you can put down — things like roofs, driveways, and pavement. That hard surface is called impervious cover. For commercial subdivisions over the aquifer, impervious cover usually cannot exceed 45%. Residential subdivisions are often capped at 30%.
Your land may also be in a city's ETJ. That is a zone outside city limits where a city can still set some rules. If so, city rules may apply on top of county rules. Call Travis County Transportation and Natural Resources at (512) 854-4215 before you plan any subdivision or big project.
Source to confirm: Travis County – Chapter 482 Development Regulations