Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Austin ADU cost →Building an ADU in Austin costs between $125,000-$250,000 for new construction, with per-square-foot costs averaging $165-$330. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $60,000-$140,000, while prefab/modular ADUs fall in between at $85,000-$200,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | $2,500-$4,000 |
| Impact Fees | $1,200-$2,000 |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. Get up to 3 free quotes from ADU builders serving Austin — no obligation.
Get Austin builder quotes →Permit fees in Austin are $2,500-$4,000. The review timeline is Confirm with Austin Development Services Department (typical 45-90 days), with plan check: 2-3 weeks. Impact fees are $1,200-$2,000. Pre-approved plans: City offers expedited review for pre-approved plans.
| 1-Bedroom Rent | $1,300-$1,900/month |
| 2-Bedroom Rent | $1,700-$2,500/month |
| Annual Rental Income (est.) | $19,200/year |
| Payback Period (est.) | 9.8 years |
| Short-Term Rental | Check local restrictions |
| Overall ROI Estimate | 7-10% annual return |
A typical ADU in Austin generates approximately $19,200 per year in rental income based on average 1-bedroom rents. At an average construction cost of $187,500, the estimated payback period is 9.8 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Austin and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Austin: $60,000-$140,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $85,000-$200,000.
3. Pre-approved plans — available in Austin, which can save $3,000-$10,000 in design costs and 2-3 months in review time.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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