Do I Need a Permit to Build an ADU in San Antonio, TX?

ADU-specific overview

What makes this different from a simple accessory structure

Pulled from the city's ADU guidance and linked code references.

Permit type: Residential new construction building permit filed through San Antonio Development Services Department (saenterprise.sanantonio.gov). An ADU is treated as a new dwelling unit subject to full UDC Article III and building code plan review.
Maximum size: 1,100 square feet of gross floor area, or 50 percent of the primary dwelling's gross floor area, whichever is less.
Setbacks: 5 feet from rear and interior side property lines. Front-yard setbacks follow the base zoning district standard. The 2022 ADU ordinance did not eliminate setback requirements.
Owner occupancy: Owner occupancy of either the primary dwelling or the ADU is generally required in San Antonio's single-family residential base zoning districts under UDC Article III. Confirm the specific owner-occupancy condition applicable to the parcel with DSD.
Parking: One off-street parking space is required for an ADU. The 2022 ADU ordinance update provides a parking waiver for ADUs located within one-quarter mile of a VIA Metropolitan Transit bus route stop. Properties outside that buffer must provide the additional parking space.
Utilities: San Antonio Water System (SAWS) and CPS Energy connections are required for each ADU. New utility taps or sub-meters may be needed depending on whether the ADU shares or separates service from the main dwelling.
JADU distinction: San Antonio's UDC does not create a California-style Junior ADU (JADU) track. Interior conversions that result in a full separate dwelling unit are treated as residential addition or new-construction permits under the standard DSD review path.

San Antonio updated its ADU ordinance in 2022, reducing minimum lot size requirements and introducing a parking waiver for transit-adjacent parcels.
Texas does not have statewide ADU preemption. San Antonio's ADU rules — size limits, setbacks, owner occupancy, and parking — are governed by local UDC Article III, not state law.
Texas HB 2127 (88th Legislature, 2023) restricts some forms of local regulation but is not an ADU-specific preemption statute. San Antonio's UDC ADU standards remain in effect.
No statewide ADU preemption law exists in Texas. San Antonio homeowners must comply with the full UDC Article III framework.

Conditions

Full permit conditions

All 8 conditions for San Antonio adu permits.

A building permit is required to construct any ADU in San Antonio. San Antonio Development Services Department (DSD) processes all residential permits, including ADUs, under the Unified Development Code (UDC) and the adopted building codes.
San Antonio's UDC Article III governs accessory dwelling units. ADUs are permitted on single-family residential lots (base zoning districts RP, R-1, R-2, R-3, R-4, R-5, R-6, NP-8, NP-10, NP-15) subject to district-specific standards.
San Antonio updated its ADU ordinance in 2022, reducing the minimum lot size required to build an ADU. Verify the current minimum lot size with DSD, as the 2022 amendments changed requirements from the prior 6,000 sq ft floor.
The ADU may not exceed 1,100 square feet of gross floor area, or 50 percent of the primary dwelling's gross floor area, whichever is less.
ADUs may not exceed 25 feet in height, or the height of the primary dwelling, whichever is less.
Minimum setbacks for an ADU are 5 feet from rear and interior side property lines. The ADU must comply with the front-yard setback of the base district.
San Antonio's 2022 ADU ordinance update includes a parking waiver for ADUs located within one-quarter mile of a VIA Metropolitan Transit bus route stop. Properties outside that proximity buffer still require one off-street parking space for the ADU.
Owner occupancy of either the primary dwelling or the ADU is required in most residential base zones. Verify the specific owner-occupancy condition that applies to your parcel with DSD.

Fees

Estimated city fees

Baseline for a simple permitted adu: $1,500–$4,500+ in combined city permit, plan review, and trade permit fees is a practical San Antonio ADU planning range before utility connection and HOA costs

Fee	Amount	Notes
Residential building permit fee	$500–$1,500 (estimated, based on construction valuation)	San Antonio DSD calculates permit fees on a sliding scale tied to declared construction value. An ADU as a new dwelling unit is priced similarly to a small residential new construction project. Verify the current fee schedule at sanantonio.gov/DSD before submitting.
Plan review fee	Included or separate depending on project scope	Plan review fees may be bundled with the building permit fee for straightforward submittals or assessed separately for larger projects. Confirm the applicable charges when you submit your application.
Trade permit fees (electrical, plumbing, mechanical)	$200–$700+ each depending on scope	Habitable ADUs require separate electrical, plumbing, and mechanical permits in addition to the main building permit.
Utility connection fees	Varies	San Antonio Water System (SAWS) and CPS Energy connection fees may apply depending on whether the ADU requires a new tap or sub-meter.

Documents

Required documents

Residential new construction building permit application submitted through San Antonio DSD's online portal at saenterprise.sanantonio.gov or in person at 1901 S. Alamo St., San Antonio, TX 78204.
Scaled site plan showing lot boundaries, existing structures, proposed ADU footprint, setback dimensions, parking space (or transit proximity waiver documentation), and utility connection points.
Architectural floor plans and elevations showing interior layout, room sizes, ceiling heights, windows, doors, and exterior design.
Structural drawings with foundation, framing, and connection details compliant with the 2021 IRC and San Antonio building code amendments.
Calculation or statement confirming the ADU gross floor area does not exceed 1,100 square feet or 50 percent of the primary dwelling GFA.
Transit proximity documentation (e.g., VIA Metropolitan Transit map showing the ADU location is within one-quarter mile of a bus stop) if claiming the parking waiver.
Trade permit applications for electrical, plumbing, and mechanical work associated with the ADU.
Owner-occupancy affidavit or declaration if required by DSD for the applicable base zoning district.

Timeline

Typical timing

Plan review: 10–15 business days for initial residential plan review
Total cycle: 6–12 weeks from application to final inspection

ADU plan review may involve zoning, building, and utilities disciplines. Resubmittals for corrections, trade permit reviews, and inspection scheduling each add time. Straightforward projects can close in 6–8 weeks; projects with revisions or utility work typically run 10–12 weeks.

Process

How the permit process works

Confirm zoning eligibility and lot requirements Use San Antonio's online mapping tools or contact DSD to confirm the parcel's base zoning district allows ADUs under UDC Article III and that the lot meets the current minimum lot size threshold established by the 2022 ADU ordinance update.
Check for transit proximity parking waiver Determine whether the parcel is within one-quarter mile of a VIA Metropolitan Transit bus route stop. If so, the 2022 ADU ordinance waives the one-space off-street parking requirement. Prepare a simple map exhibit showing the parcel's proximity to the nearest bus stop to support the waiver.
Prepare permit documents Assemble a complete application package including site plan, architectural and structural drawings, GFA calculation confirming compliance with the 1,100 sq ft / 50% limit, and utility connection plan. Confirm all setbacks satisfy UDC Article III minimums.
Submit permit application and pay fees Submit the residential new construction permit application through San Antonio DSD's portal at saenterprise.sanantonio.gov or in person at the DSD offices. Pay the calculated permit and plan review fees at submission.
Work through plan review comments DSD plan reviewers evaluate the submittal against the 2021 IRC, San Antonio building code amendments, and UDC Article III standards. Respond to correction notices and resubmit updated drawings through the portal.
Obtain trade permits and utility connections File electrical, plumbing, and mechanical permits for the ADU's systems. Coordinate with SAWS and CPS Energy for utility connections and any required new taps.
Schedule inspections and close out permits Schedule required inspections — foundation, framing, rough-in trades, energy, and final — through DSD's inspection scheduling system. Once all inspections pass and permits are finaled, the ADU is cleared for occupancy.

Code basis

What San Antonio reviews against

2021 International Residential Code (IRC) with San Antonio local amendments; San Antonio Unified Development Code (UDC) Article III (Residential District Standards and Accessory Dwelling Unit Standards), as updated by the 2022 ADU ordinance amendments.

Residential permit page San Antonio permit portal

If you skip the permit

What can go wrong

San Antonio DSD can issue a stop-work order and require after-the-fact permitting for any unpermitted dwelling unit, including removal if the structure cannot be brought into compliance.
An unpermitted ADU that violates UDC setback, size, or owner-occupancy requirements may be required to be demolished or modified at the owner's expense.
Fines and daily penalties can accrue under San Antonio's code enforcement ordinance until the violation is resolved.
Homeowner's insurance may deny claims for damage to or caused by an unpermitted structure not inspected for code compliance.
An unpermitted ADU can block or complicate a refinance, HELOC, or home sale due to disclosure requirements and lender underwriting standards.
Without a certificate of occupancy, the ADU cannot be lawfully occupied or rented, and rental income may be legally unprotected.

FAQ

Common San Antonio adu permit questions

Do I need a permit to build an ADU in San Antonio, TX?

Yes. San Antonio requires a residential new construction building permit for any ADU. The city treats an ADU as a new dwelling unit subject to full UDC Article III and building code plan review.

What changed in San Antonio's 2022 ADU ordinance update?

San Antonio's 2022 amendments reduced the minimum lot size required to build an ADU and introduced a parking waiver for ADUs located within one-quarter mile of a VIA Metropolitan Transit bus route stop. The 2022 update made it easier for more homeowners on smaller lots and near transit to build ADUs than under the prior ordinance.

How big can an ADU be in San Antonio?

The ADU cannot exceed 1,100 square feet of gross floor area, or 50 percent of the primary dwelling's gross floor area, whichever is less.

Does San Antonio require owner occupancy for an ADU?

Generally yes. San Antonio's UDC Article III requires the property owner to occupy either the primary dwelling or the ADU in most single-family residential base zones. Confirm the specific condition that applies to your parcel with DSD before applying.

Can I avoid adding a parking space for my San Antonio ADU?

Yes, if the ADU is within one-quarter mile of a VIA Metropolitan Transit bus route stop. The 2022 ADU ordinance update provides a parking waiver for qualifying locations. Prepare a map exhibit showing the proximity to the nearest bus stop to support the waiver when you submit your permit application.

How long does San Antonio ADU plan review take?

Initial residential plan review typically takes 10–15 business days. Total project time including trade permits, utility connections, inspections, and any resubmittals is usually 6–12 weeks.

Does Texas have a statewide ADU preemption law?

No. Texas does not have a dedicated statewide ADU preemption law comparable to California, Oregon, or Washington. San Antonio's UDC Article III standards — including size limits, setbacks, owner occupancy, and parking requirements — remain fully in effect. Texas HB 2127 (2023) restricts certain local economic regulations but is not an ADU-specific statute.

What building code does San Antonio use for ADUs?

San Antonio uses the 2021 International Residential Code (IRC) with local amendments. ADU dimensional and use standards are governed by the San Antonio Unified Development Code (UDC) Article III, as updated by the 2022 ADU ordinance amendments.

Sources

Official links and freshness

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