Accessory Structures in San Antonio, TX

If you live in San Antonio or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. San Antonio has 3 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

ADU Rules

San Antonio caps accessory dwelling units at 800 square feet, or up to 1,600 square feet if that stays under half the primary home's floor area, under UDC Sec. 35-371. Detached units need a permit, a 5-foot rear and side setback, one parking space over 800 square feet, and a maximum height of 25 feet or two stories.

Key details: Base ADU size limit: 800 square feet. Max ADU size (non-FR districts): 1,600 square feet. Max ADU size in RE district: 1,200 square feet. ADDU setback (rear/side): 5 feet, or 3 feet without overhang. ADDU height cap: 25 feet or 2 stories.

Building or occupying an accessory dwelling without the required permit, or exceeding the 800/1,600-square-foot size caps or the 5-foot ADDU setback, is a zoning violation under UDC Article III. Sec. 35-491(c)(2) sets the criminal fine at $100 to $2,000 per day, rising to $200 on a second conviction and $300 on later ones, and the city can also seek a civil penalty of up to $1,000 per day of noncompliance.

ADU Owner Occupancy

San Antonio requires the property owner to live in either the main house or the accessory dwelling as a permanent residence under UDC Sec. 35-371(a)(1), and bars charging rent on the owner-occupied unit. Owners must sign a notarized affidavit and record a covenant binding future owners to the occupancy condition.

Key details: Owner-occupancy mandate: Owner must live in main home or ADU. Rent restriction: No rent charged on owner-occupied unit. Proof required: Notarized affidavit before permit issuance. Recording requirement: Covenant recorded with county recorder. Governing section: UDC Sec. 35-371(a)(1).

Renting out both the principal dwelling and the accessory unit with no owner in residence, or failing to record the required covenant, breaches the Sec. 35-371(a)(1) condition and is enforced as an Article III zoning violation under Sec. 35-491(c)(2): a $100 to $2,000 daily criminal fine, rising to $200 on a second conviction and $300 on later ones, plus a possible civil penalty of up to $1,000 per day.

Compared to other cities, San Antonio takes a harder line on adu owner occupancy. The enforcement and penalty structure reflects that.

ADU Rental Restrictions

San Antonio bars pure rental income from accessory dwelling units: the property owner must live in either the main house or the ADU as a permanent residence and can never collect rent on the unit they occupy. A notarized affidavit and a covenant recorded with the county lock this rule to the deed, and any ADU rented short-term must separately clear UDC Section 35-374.01.

Key details: Owner-occupancy rule: Owner must live in main house or ADU. Rent ban: No rent allowed on the owner-occupied unit. Recorded proof: Notarized affidavit plus covenant recorded with county. ADU size cap: 800 sq ft or 50% of primary home, max 1,600. STR overlay: Short-term rental ADUs must also meet Sec. 35-374.01.

Section 35-371 sits in UDC Article III, Zoning, so violations carry Section 35-491(c)(2) penalties: a criminal fine of $100 to $2,000 per offense, rising to a $200 minimum on a second conviction and a $300 minimum on a third and later conviction, with each day of noncompliance a separate offense. The city may also pursue a civil penalty of up to $1,000 per day and can sue to enjoin an unauthorized rental or force vacancy of the unit under Section 35-491(a).

This is one of the stricter rules in San Antonio's municipal code. If you are unsure whether your situation complies, it is worth checking with the city before proceeding.

The Bottom Line

San Antonio is tougher than many cities when it comes to accessory structures. Out of the 3 rules covered here, 2 are rated strict. If you are a homeowner, renter, or business owner in San Antonio, take the time to understand these requirements before they become a problem. Most violations come with fines, and some repeat violations can escalate.

All of the above reflects San Antonio's municipal code as of our last review. If you need specifics on fines, exemptions, or filing requirements, the detailed ordinance pages linked above have the full breakdown.