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ADU Rules in San Antonio, Texas

Complete guide to building an Accessory Dwelling Unit in San Antonio — zoning, setbacks, permits, costs, and more.

Max Size: The larger of 800 sq ft gross floor area or 50% of the main house's gross floor area, capped at 1,600 sq ft (UDC 35-371; IB 402 FAQ 1). Every lot may therefore have an ADU of at least 800 sq ft regardless of the size of the main house. Setbacks: 5 ft standard for a detached ADU; may be reduced to 3 ft if the structure has no eave overhang within 3 ft of the line, and walls within 5 ft of the line must be fire-rated under the IRC (IB 402 FAQ 2; DSD ADU page). The ADU must be located in the rear of the lot (IB 402 FAQ 4). No Parking Required Verified: 2026-09-20

Researched by ADU Zoning Hub · verified 2026-09-20 against San Antonio planning code and Texas ADU law · methodology · 19 sources cited ↓

ADU Score: 7/10
Moderately friendly · how we score

Are ADUs allowed in San Antonio, TX? [1][2][3][4]

Yes. San Antonio allows ADUs on most residential lots. A detached unit can be up to the city's size limit, set 5 ft back from the rear line. No extra parking is required. Owner-occupancy is required. A building permit is required and applications are reviewed through the standard permit process.

Maximum sizeThe larger of 800 sq ft gross floor area or 50% of the main house's gross floor area, capped at 1,600 sq ft (UDC 35-371; IB 402 FAQ 1). Every lot may therefore have an ADU of at least 800 sq ft regardless of the size of the main house.
SetbacksRear 5 ft standard for a detached ADU; may be reduced to 3 ft if the structure has no eave overhang within 3 ft of the line, and walls within 5 ft of the line must be fire-rated under the IRC (IB 402 FAQ 2; DSD ADU page). The ADU must be located in the rear of the lot (IB 402 FAQ 4). · Side 5 ft standard for a detached ADU; 3 ft allowed with no eave overhang and IRC fire rating within 5 ft of the line (IB 402 FAQ 2). An attached ADU keeps the main house's district side setback.
ParkingNone required for an ADU of 800 sq ft or less. An ADU over 800 sq ft gross floor area needs one dedicated off-street parking space (IB 402 FAQ 4; DSD ADU page).
Owner-occupancyRequired. The owner must occupy either the main house or the ADU as a permanent residence, sign a notarized affidavit, and record a covenant with the Bexar County Clerk before the permit issues; the owner-occupied unit may never be rented (UDC 35-371(a)(1); IB 402 Attachment B). Enforcement uses voter registration, homestead and driver's-license records and cross-checks against STR permits.

Do I need a permit to build an ADU in San Antonio? [5][6][7][8][9]

Yes. Every ADU in San Antonio needs a building permit. Review process: By right, no zoning hearing: file a Residential Building Permit in BuildSA (a combination permit covering building, electrical, mechanical and plumbing) with a site plan, foundation plan, IECC energy report and Manual J/S HVAC sizing, plus proof that the owner-occupancy affidavit and covenant are recorded with Bexar County (IB 402; DSD ADU page). One of the five city Casita Permit-Ready Plans can serve as the building plans..

Permit feesFY2026 DSD fee schedule (rev. Oct 2025), new residential construction by size: $988 total basic permit fees for 501-1,000 sq ft, $1,022 for 1,001-1,250 and $1,201 for 1,251-1,500 sq ft (building, trade and sewer permits plus a $200 plan review). 100% waivable for income-qualified ADUs.
Typical timelineDSD publishes only its review targets: up to 3 business days for intake/completeness review and up to 3 business days for the first plan-review redlines; the permit issues once corrections are accepted and fees paid (DSD ADU page; DSD fact sheet 3/28/2023). Total time to permit is not published.
Official San Antonio links:

Three things to know before you build in San Antonio

  • Cost basis: DFW casita guide (June 29, 2026) $250-$400 per finished sq ft and $150,000-$400,000+ for 600-1,000 sq ft, garage-shell finish $30,000-$60,000; modular installed $200,000-$400,000+ (May 2026); a San Antonio guide gives $125,000-$350,000. San Antonio labor runs below DFW, so the ranges here start lower.
  • Record the affidavit and covenant at the Bexar County Clerk (101 W. Nueva St., Suite 103) before you apply: BuildSA will not process the ADU permit without proof of recording (IB 402).
  • Keep the unit at 800 sq ft or less and you owe no parking space. At 3 ft from a side or rear line you give up eave overhangs and need fire-rated walls; at 5 ft you do not.

Last verified 2026-09-20 against San Antonio planning code. How we verify

San Antonio allows one accessory dwelling unit (the city calls it a casita) by right on lots in every single-family and mixed-residential district (R-1 through R-6, RM-4 through RM-6) and on multi-family lots of up to five units, under UDC 35-371. The unit may be the larger of 800 sq ft or 50% of the main house, up to 1,600 sq ft; a detached unit may be two stories and 25 ft tall and sit 3 ft from side and rear lines. The catch is owner-occupancy: you must live in the house or the ADU and record an affidavit and covenant with the Bexar County Clerk before Development Services issues the permit. City permit and plan-review fees total about $988 for an 800 sq ft unit (FY2026 schedule), five permit-ready casita plans are available for a $450 base fee, and income-qualified owners can get up to $35,000 in forgivable loans plus 100% fee waivers.

Zoning & Size Requirements [1][2][3][4]

Yes — San Antonio allows ADUs. The size limit is a formula rather than one figure — see the size rule in the table below — under current Texas and San Antonio zoning rules.

See what this means for your lot — ask San Antonio ADU builders for a quote →

Allowed ZonesPermitted by right in R-1, R-2, R-3, R-4, R-5, R-6, RM-4, RM-5 and RM-6, and in multi-family districts on lots with up to five units in total (UDC 35-371; DSD ADU page, 2026). A lot whose owner will not live on site must instead be rezoned to a district that allows more than one dwelling. Check your district on the city's OneStop map; recorded deed restrictions and HOA rules still apply.
Max Size (Detached)The larger of 800 sq ft gross floor area or 50% of the main house's gross floor area, capped at 1,600 sq ft (UDC 35-371; IB 402 FAQ 1). Every lot may therefore have an ADU of at least 800 sq ft regardless of the size of the main house.
Max Size (Attached)Same formula as a detached unit: the larger of 800 sq ft or 50% of the main house's gross floor area, up to 1,600 sq ft (DSD: the size rule applies to attached and detached ADUs). No limit on bedrooms.
Max Size (JADU)No junior ADU category in the San Antonio UDC; a unit carved out of, or added onto, the house is simply an attached ADU under UDC 35-371 and uses the same size rule.
Max HeightDetached ADU: 2 stories and 25 ft maximum (IB 402 FAQ 4; DSD ADU page). Attached ADU: the height limit of the underlying zoning district.
Max UnitsOne ADU per lot (IB 402 FAQ 4; DSD ADU page). In multi-family districts the lot may hold no more than five units in total including the ADU.

Setback Requirements [1][2][3][4]

San Antonio requires a rear setback of about 5 ft for a detached ADU, and no additional parking is required. Owner-occupancy is required.

Rear Setback5 ft standard for a detached ADU; may be reduced to 3 ft if the structure has no eave overhang within 3 ft of the line, and walls within 5 ft of the line must be fire-rated under the IRC (IB 402 FAQ 2; DSD ADU page). The ADU must be located in the rear of the lot (IB 402 FAQ 4).
Side Setback5 ft standard for a detached ADU; 3 ft allowed with no eave overhang and IRC fire rating within 5 ft of the line (IB 402 FAQ 2). An attached ADU keeps the main house's district side setback.
Front SetbackNo ADU-specific front setback: the unit must sit in the rear of the lot (IB 402 FAQ 4), so the main house's district front setback governs. Confirm your district's setback table with DSD Zoning (210-207-1111).
Parking RequiredNone required for an ADU of 800 sq ft or less. An ADU over 800 sq ft gross floor area needs one dedicated off-street parking space (IB 402 FAQ 4; DSD ADU page).
Owner OccupancyRequired. The owner must occupy either the main house or the ADU as a permanent residence, sign a notarized affidavit, and record a covenant with the Bexar County Clerk before the permit issues; the owner-occupied unit may never be rented (UDC 35-371(a)(1); IB 402 Attachment B). Enforcement uses voter registration, homestead and driver's-license records and cross-checks against STR permits.
Min Lot SizeNo ADU-specific minimum lot size in UDC 35-371, IB 402 or the DSD ADU page; the district's lot standards for the main house apply. Confirm with DSD Zoning.

Permit Process & Fees [5][6][7][8][9]

An ADU permit in San Antonio goes through a standard permit review. Typical timeline: DSD publishes only its review targets: up to 3 business days for intake/completeness review and up to 3 business days for the first plan-review redlines; the permit issues once corrections are accepted and fees paid (DSD ADU page; DSD fact sheet 3/28/2023). Total time to permit is not published. Permit fees: FY2026 DSD fee schedule (rev. Oct 2025), new residential construction by size: $988 total basic permit fees for 501-1,000 sq ft, $1,022 for 1,001-1,250 and $1,201 for 1,251-1,500 sq ft (building, trade and sewer permits plus a $200 plan review). 100% waivable for income-qualified ADUs.

Approval ProcessBy right, no zoning hearing: file a Residential Building Permit in BuildSA (a combination permit covering building, electrical, mechanical and plumbing) with a site plan, foundation plan, IECC energy report and Manual J/S HVAC sizing, plus proof that the owner-occupancy affidavit and covenant are recorded with Bexar County (IB 402; DSD ADU page). One of the five city Casita Permit-Ready Plans can serve as the building plans.
Review TimelineDSD publishes only its review targets: up to 3 business days for intake/completeness review and up to 3 business days for the first plan-review redlines; the permit issues once corrections are accepted and fees paid (DSD ADU page; DSD fact sheet 3/28/2023). Total time to permit is not published.
Permit FeesFY2026 DSD fee schedule (rev. Oct 2025), new residential construction by size: $988 total basic permit fees for 501-1,000 sq ft, $1,022 for 1,001-1,250 and $1,201 for 1,251-1,500 sq ft (building, trade and sewer permits plus a $200 plan review). 100% waivable for income-qualified ADUs.
Impact FeesThe City itself charges no impact fee. SAWS water and wastewater impact fees (effective July 1, 2024; about $7,300-$12,000 per EDU combined, by service area) apply only if the ADU adds service beyond the lot's platted EDU, e.g. a separate meter; waivable for income-qualified ADUs under the Fee Waiver Program.
Plan CheckUp to 3 business days to first redline comments (DSD ADU page)
Pre-Approved PlansYes: 5 Casita Permit-Ready Plans (375, 490, 675, 794 and 800 sq ft), reviewed and approved by DSD as complete building plans; $450 base fee paid to the designer, site-specific changes priced separately; owners at or below 80% AMI can get up to $4,500 design-fee reimbursement

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Construction Costs [10][11][12][13]

Building an ADU in San Antonio typically costs $125,000-$320,000 ($225-$400 per sq ft); a garage conversion runs $30,000-$90,000.

See what this means for your lot — ask San Antonio ADU builders for a quote →

Average Build Cost$125,000-$320,000
Cost per Sq Ft$225-$400
Garage Conversion$30,000-$90,000
Prefab ADU (Installed)$150,000-$300,000

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Rental Income Potential [14][15][16]

A 2-bedroom ADU in San Antonio rents for around $1,200-$1,500/mo, an estimated 4-8% gross rent yield.

Avg Rent (1 Bedroom)$950-$1,250/mo
Avg Rent (2 Bedroom)$1,200-$1,500/mo
Short-Term RentalOnly with a City STR permit (UDC 35-374.01): Type 1 owner-occupied lot, $300 application, 3-year term, one permit per unit, blockface density caps.
Est. Annual ROI4-8% gross rent yield

Explore Prefab ADU Options

Prefab ADUs can save 20-40% vs. traditional construction and cut build time in half.

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Recent Law Changes

What's Changed Recently

  • 2026-09-20: entry re-verified against the DSD ADU permit page, Information Bulletin 402 (Jan 1, 2023), the DSD ADU fact sheet (rev. Mar 28, 2023), the FY2026 Development Fee Schedule (rev. Oct 2025) and SAWS's July 1, 2024 impact-fee table; size, setback, height, parking, fee, plan-library and incentive figures corrected and the old 'conditional use permit' and '$4,000-$6,500 fee' claims removed.
  • Casita Incentives Pilot Program is open (2026): no-interest forgivable loans of up to $25,000 (5-year) or $35,000 (10-year) for owner-occupied casitas with income-qualified owners or renters, plus up to $4,500 design-fee reimbursement and City/SAWS fee waivers; casitas used as short-term rentals are ineligible.
  • Casita Permit-Ready Plan Library (from the city's March 2024 RFQ): five DSD-approved plans of 375-800 sq ft, $450 base fee; the city planned additional plan-fee incentives from fall 2025.
  • COSA Fee Waiver Program: FY2026 applications opened January 2026; affordable housing including ADUs qualifies for a 100% waiver of City development and permit fees plus SAWS impact-fee waivers, when the ADU or main house is rented to a household at or below 80% AMI (rent capped at 30% of income) for 5 years after the certificate of occupancy.
  • No ADU text change since the Nov 3, 2022 UDC amendment ordinance (2022-11-03-0831): the current 800 sq ft / 50% / 1,600 sq ft standard appears in DSD's January 2023 bulletin, replacing the earlier 35%-of-house cap for attached units (BoA case 21-1654). The 2025 out-of-cycle amendments track new state laws; the next UDC amendment cycle opens January 2027.
  • Texas: SB 673 (statewide ADU preemption) died in the House, last action May 26, 2025 (placed on General State Calendar); SB 15 (small-lot homes), HB 24 and SB 840 carry no ADU provision, so no state ADU floor applies in 2026. The Legislature next convenes January 12, 2027.

Tips for Building an ADU in San Antonio

  • Cost basis: DFW casita guide (June 29, 2026) $250-$400 per finished sq ft and $150,000-$400,000+ for 600-1,000 sq ft, garage-shell finish $30,000-$60,000; modular installed $200,000-$400,000+ (May 2026); a San Antonio guide gives $125,000-$350,000. San Antonio labor runs below DFW, so the ranges here start lower.
  • Record the affidavit and covenant at the Bexar County Clerk (101 W. Nueva St., Suite 103) before you apply: BuildSA will not process the ADU permit without proof of recording (IB 402).
  • Keep the unit at 800 sq ft or less and you owe no parking space. At 3 ft from a side or rear line you give up eave overhangs and need fire-rated walls; at 5 ft you do not.
  • Fee example: an 800 sq ft ADU pays $988 in basic permit and plan-review fees on the FY2026 schedule; optional TML, TOPS and gas permits add $54-$64 each. SAWS impact fees arise only if you add a meter.
  • Income-qualified owners should apply to the Casita Incentives Pilot (up to $35,000 forgivable) and the Fee Waiver Program before pulling the permit; both depend on funding availability, and the casita must not be a short-term rental.
  • The Casita program asks for an HOA letter confirming a casita may be built; check deed restrictions first, and expect Historic and Design Review Commission review in a historic district.
  • Cost basis (2026-09-20 re-verification): short term allowed: Only with a City STR permit (UDC 35-374.01): Type 1 owner-occupied lot, $300 application, 3-year term, one permit per unit, blockface density caps. A casita rented for under 30 days is ineligible for the Casita Incentive; confirm ADU eligibility with DSD before listing.

ADU Builders in San Antonio

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Sources & References

All data on this page is sourced from official government records and verified market data. View our full methodology.

  1. Accessory Dwelling Unit (ADU) Permits, ADU Development Requirements — City of San Antonio Development Services Planning Department — Accessed 2026-09-20
  2. Information Bulletin 402 — Accessory Dwelling Units (DSD Plan Review Division, Jan 1, 2023; Wayback capture 2025-04-30) Planning Department — Accessed 2026-09-20
  3. Accessory Dwelling Units Fact Sheet (DSD, rev. 2023-03-28; Wayback capture 2025-03-02) Planning Department — Accessed 2026-09-20
  4. San Antonio Unified Development Code Ch. 35, § 35-371 Accessory Dwellings (Municode; bot-walled Sept 2026, rules taken from DSD's own bulletins) Municipal Code — Accessed 2026-09-20
  5. FY2026 Development Fee Schedule, rev. October 2025 — Residential Construction: New, Remodels and Additions, p. 4 (Wayback capture 2025-12-11) Planning Department — Accessed 2026-09-20
  6. Casita Permit-Ready Plan Library — City of San Antonio Neighborhood & Housing Services Planning Department — Accessed 2026-09-20
  7. Casita Incentives Pilot Program — City of San Antonio Neighborhood & Housing Services Planning Department — Accessed 2026-09-20
  8. SAWS Impact Fees, effective July 1, 2024 (San Antonio Water System; Wayback capture 2025-11-05) Government Data — Accessed 2026-09-20
  9. STR Permits — City of San Antonio Development Services Planning Department — Accessed 2026-09-20
  10. DFW ADU & Casita Cost Guide 2026 (June 29, 2026), UHS Remodeling industry — Accessed 2026-09-20
  11. Cost To Convert Garage Into Living Space In DFW Texas 2026 (April 24, 2026), UHS Remodeling industry — Accessed 2026-09-20
  12. Prefab Modular ADU: 2026 Costs, Code Paths & Lot Fit (updated May 27, 2026), Dwelling Index industry — Accessed 2026-09-20
  13. How to Build an ADU in San Antonio, Texas (rules as of Aug 2022), Maxable industry — Accessed 2026-09-20
  14. HUD FY2027 Fair Market Rents — San Antonio-New Braunfels, TX HMFA (1BR $1,196, 2BR $1,441) Government Data — Accessed 2026-09-20
  15. HUD FY2027 Small Area FMRs — San Antonio ZIP codes 78202-78236 Government Data — Accessed 2026-09-20
  16. Zumper San Antonio Rent Research (updated Sept 19, 2026: 1BR $944, 2BR $1,250) Market Data — Accessed 2026-09-20
  17. Unified Development Code (UDC) — amendment process, 2025 out-of-cycle amendments, next cycle January 2027 (City of San Antonio DSD) Planning Department — Accessed 2026-09-20
  18. Texas Legislature Online — SB 673 (89R) bill history: last action 05/26/2025 H Placed on General State Calendar Government Data — Accessed 2026-09-20
  19. Texas Local Government Code Ch. 211 — Municipal Zoning Authority Government Data — Accessed 2026-09-20

Frequently Asked Questions

Can I build an ADU in San Antonio?

Yes. ADUs are allowed in Permitted by right in R-1, R-2, R-3, R-4, R-5, R-6, RM-4, RM-5 and RM-6, and in multi-family districts on lots with up to five units in total (UDC 35-371; DSD ADU page, 2026). A lot whose owner will not live on site must instead be rezoned to a district that allows more than one dwelling. Check your district on the city's OneStop map; recorded deed restrictions and HOA rules still apply. in San Antonio. The maximum size for a detached ADU is The larger of 800 sq ft gross floor area or 50% of the main house's gross floor area, capped at 1,600 sq ft (UDC 35-371; IB 402 FAQ 1). Every lot may therefore have an ADU of at least 800 sq ft regardless of the size of the main house.. Owner-occupancy is required: Required. The owner must occupy either the main house or the ADU as a permanent residence, sign a notarized affidavit, and record a covenant with the Bexar County Clerk before the permit issues; the owner-occupied unit may never be rented (UDC 35-371(a)(1); IB 402 Attachment B). Enforcement uses voter registration, homestead and driver's-license records and cross-checks against STR permits.

How much does an ADU cost in San Antonio?

ADU construction in San Antonio typically costs $125,000-$320,000. Garage conversions run $30,000-$90,000, and prefab ADUs cost $150,000-$300,000.

How much can I rent an ADU for in San Antonio?

Average ADU rents in San Antonio are $950-$1,250/mo for a 1-bedroom and $1,200-$1,500/mo for a 2-bedroom unit.

Do I need parking for an ADU in San Antonio?

None required for an ADU of 800 sq ft or less. An ADU over 800 sq ft gross floor area needs one dedicated off-street parking space (IB 402 FAQ 4; DSD ADU page).. Check with San Antonio planning department for the latest Texas ADU parking rules, as many states have relaxed requirements in recent years.

How long does it take to get an ADU permit in San Antonio?

The permit review timeline in San Antonio is DSD publishes only its review targets: up to 3 business days for intake/completeness review and up to 3 business days for the first plan-review redlines; the permit issues once corrections are accepted and fees paid (DSD ADU page; DSD fact sheet 3/28/2023). Total time to permit is not published.. Permit fees: FY2026 DSD fee schedule (rev. Oct 2025), new residential construction by size: $988 total basic permit fees for 501-1,000 sq ft, $1,022 for 1,001-1,250 and $1,201 for 1,251-1,500 sq ft (building, trade and sewer permits plus a $200 plan review). 100% waivable for income-qualified ADUs.

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FAQ

San Antonio ADU FAQ

Answers to every common question about building an ADU in San Antonio — costs, rules, permits, rental income.

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Detailed cost breakdown: construction $125,000-$320,000, garage conversion $30,000-$90,000, plus ROI analysis.

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About this information: This page is an informational summary of publicly available regulations - it is not legal, financial, or professional advice, and it is not a substitute for confirming requirements with your local planning department. Rules change frequently; always verify current requirements before designing, budgeting, or building. Last verified: 2026-09-20. Contractors we introduce are independent businesses - verify license and insurance directly before hiring. Spotted an error? Tell us - we verify against primary sources and correct quickly.

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