Zoning & Size Limits
| Requirement | Austin, TX | San Antonio, TX |
|---|
| Allowed Zones | SF3, SF2, SF1, MU, UR, etc. | Selected residential zones only |
| Max Size (Detached) | 1,350 sq ft or 0.15 FAR (whichever is smaller; updated by HOME Phase 2, May 2024) | 800 sq ft |
| Max Size (Attached) | 1,350 sq ft or 0.15 FAR (whichever is smaller) | Not typically allowed |
| Max Height | 35 feet | 30 feet |
| Parking Required | 1 space for primary, optional for ADU | 2 spaces |
| Owner Occupancy | Not required | Not required |
Setback Requirements
| Setback | Austin, TX | San Antonio, TX |
|---|
| Rear Setback | 10 feet | 20 feet |
| Side Setback | 3 feet (with easement) | 5 feet |
| Front Setback | 20 feet | 25 feet |
Permits & Timeline
| Detail | Austin, TX | San Antonio, TX |
|---|
| Permit Timeline | 45-60 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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