Bexar County, TX Accessory Structures: ADU Rules (2026)

San Antonio adopted ADU-friendly changes in its Unified Development Code, allowing detached and attached accessory dwelling units in several residential zoning districts. Typical limits cap ADU floor area at around 800 square feet or a percentage of the primary structure, require compatible building materials, and restrict short-term rental use unless separately permitted. Owner-occupancy of either the main home or the ADU is frequently required. Parking is usually an additional one space, waived in some transit-served districts. In unincorporated Bexar County, no zoning ordinance exists, so secondary dwellings are not limited by count but must comply with Texas Commission on Environmental Quality on-site sewage facility rules for septic sizing with the total bedroom count, and with Bexar County Public Works floodplain review if in a mapped flood zone. Suburban cities such as Schertz, Helotes, and Live Oak have more restrictive ADU rules, sometimes prohibiting detached secondary dwellings. HOAs often prohibit rentals and detached units, so covenant review is essential.