ADU Rules in San Antonio, TX (2026)
ADU rules, permit requirements, size limits, and fees for San Antonio, TX. Source-cited from official municipal code.
Yes, ADUs are allowed in San Antonio, TX.
San Antonio, TX permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In San Antonio, the City of San Antonio Development Services Department (DSD) handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in San Antonio.
ADU Size Limits
ADU Size Limits in San Antonio: Detached ADU: up to 1000 sq ft (max height: 28 feet). Attached ADU: No greater than 50% of main dwelling floor area. San Antonio UDC Section 35-311 governs secondary dwelling units. Detached secondary dwelling units are limited to 1,000 sqft. JADU is a California-specific concept not applicable in Texas.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 1000 sq ft | 28 feet |
| Attached ADU | No greater than 50% of main dwelling floor area | Per zone height limit |
Permit Fees
ADU Permit Fees in San Antonio: Plan check fee: $250–$1,500. Building permit fee: Based on construction value — typically $800–$3,500. Impact fees: $500–$3,000 depending on location and utility connections. School fees: None or N/A. Total estimated permit cost: $2,000–$8,000 total fees. San Antonio Development Services Department fee schedule available at sanantonio.gov/DSD. Water/wastewater connection fees from SAWS (San Antonio Water System) apply for new service connections.
| Fee Type | Amount |
|---|---|
| Plan Check | $250–$1,500 |
| Building Permit | Based on construction value — typically $800–$3,500 |
| Impact Fees | $500–$3,000 depending on location and utility connections |
| School Fees | None |
| Total Estimate | $2,000–$8,000 total fees |
Permit Timeline
San Antonio ADU Permit Timeline: San Antonio DSD building permit: typically 4-8 weeks plan review. Electronic plan review available through the DSDepermit portal. Construction typically 4-12 months. Apply through the City of San Antonio Development Services Department (DSD) online permit portal. Phone: (210) 207-1111.
Setback Requirements
ADU Setback Requirements in San Antonio: Front setback: follows zone standard. Side setback: 5 feet. Rear setback: 5 feet. Secondary dwelling units must maintain 5 ft rear and side setbacks in most residential zones. Alley-facing lots may have reduced requirements. San Antonio UDC Section 35-311.
Parking Requirements
Parking Requirements: 1 parking space required per secondary dwelling unit. Parking requirements may be reduced in designated transit corridors near VIA Metropolitan Transit routes.
Restrictions & Requirements
- Secondary dwelling unit must be on the same lot as the primary residence
- One secondary dwelling unit per residential lot
- Must comply with lot coverage limits for the applicable zone
- Cannot be sold or conveyed separately from the primary lot
- Must meet minimum setback requirements per UDC Section 35-311
- Short-term rental requires STR registration with the city
How Many ADUs Are Allowed?
Number of ADUs Allowed in San Antonio: Single-family lots: 1 secondary dwelling unit per single-family lot. Multifamily properties: Not applicable as a separate accessory unit in RM zones. San Antonio UDC allows one secondary dwelling unit per R-1 through R-6 lot. RM-4 through RM-6 zones allow multiple residential units by right.
Single-Family Lots
1 secondary dwelling unit per single-family lot
Multifamily Properties
Not applicable as a separate accessory unit in RM zones
Historic District Considerations
Historic District Requirements: San Antonio has 12 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. San Antonio has one of the strongest historic preservation programs in Texas, reflecting the city's rich Spanish colonial and frontier heritage. Local historic districts include King William, Lavaca, Government Hill, Alta Vista, and Beacon Hill. The San Antonio Missions (UNESCO World Heritage Site) area has distinct federal and state protections. Historic Design and Review Commission (HDRC) reviews all exterior alterations to landmarks and contributing structures. Certificate of Appropriateness required before permits are issued. Look up historic district boundaries at: https://www.sanantonio.gov/Historic
Frequently Asked Questions
Can I build an ADU in San Antonio?
Yes. San Antonio, TX allows accessory dwelling units. On a single-family lot you can build 1 secondary dwelling unit per single-family lot.
How big can an ADU be in San Antonio?
The maximum size for a detached ADU in San Antonio is 1,000 square feet.
How long does it take to get an ADU permit in San Antonio?
The typical ADU permit timeline in San Antonio is San Antonio DSD building permit: typically 4-8 weeks plan review. Electronic plan review available through the DSDepermit portal. Construction typically 4-12 months.. Total estimated permit fees are $2,000–$8,000 total fees.
Do I need extra parking for an ADU in San Antonio?
No, San Antonio does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in San Antonio?
No, owner-occupancy is not required for ADUs in San Antonio.
Source: San Antonio Unified Development Code (UDC) Section 35-311 — Secondary Dwelling Units; library.municode.com/tx/san_antonio. Last verified April 6, 2026. View source