Zoning & Size Limits
| Requirement | Austin, TX | San Antonio, TX |
|---|
| Allowed Zones | SF3, SF2, SF1, MU, UR, etc. | Permitted by right (subject to use-specific standards) in mo |
| Max Size (Detached) | Lesser of 1,100 sq ft or 15% of lot area (HOME Initiative). 2nd-story floor area capped at 550 sq ft. | 800 sq ft (1,200 sq ft in the RE zone) per UDC §35-371 |
| Max Size (Attached) | Lesser of 1,100 sq ft or 15% of lot area (HOME Initiative) | Up to 35% of the principal dwelling's living area (UDC §35-371) |
| Max Height | 30 feet (2 stories typical under HOME) | Generally may not exceed the height of the primary |
| Parking Required | No off-street parking required for ADUs under 550 sq ft; 1 s | One on-site space required only if the ADU exceeds 800 sq ft |
| Owner Occupancy | Not required | Required — owner must occupy either the principal unit or th |
Setback Requirements
| Setback | Austin, TX | San Antonio, TX |
|---|
| Rear Setback | 10 feet | 5 feet (detached ADU may be 3 ft or more from side and rear lines per UDC §35-371) |
| Side Setback | 5 feet | 5 feet |
| Front Setback | 25 feet | 25 feet |
Permits & Timeline
| Detail | Austin, TX | San Antonio, TX |
|---|
| Permit Timeline | Confirm with Austin Development Services Department (typical 45-90 days) | 90-120 days |
| Permit Fees | $2,500-$4,000 | $4,000-$6,500 |
| Impact Fees | $1,200-$2,000 | $1,200-$2,200 |
| Pre-Approved Plans | City offers expedited review for pre-approved plan | Not available |
Construction Costs
| Cost | Austin, TX | San Antonio, TX |
|---|
| Avg Build Cost | $125,000-$250,000 | $110,000-$220,000 |
| Cost Per Sq Ft | $165-$330 | $140-$275 |
| Garage Conversion | $60,000-$140,000 | $50,000-$130,000 |
| Prefab ADU | $85,000-$200,000 | $75,000-$170,000 |
Rental Income Potential
| Rental | Austin, TX | San Antonio, TX |
|---|
| 1BR Avg Rent | $1,300-$1,900/mo | $1,050-$1,550/mo |
| 2BR Avg Rent | $1,700-$2,500/mo | $1,300-$1,950/mo |
| Short-Term Rentals | Check local restrictions | Not permitted |
| Est. ROI | 7-10% annual return | 5-7% annual return |
Which City Is Better for ADUs?
Austin scores 8/10 while San Antonio scores 5/10 on our ADU-friendliness index.
Austin edges ahead overall. Both cities offer viable ADU development opportunities — the best choice depends on your specific property, budget, and goals.
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