Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Austin ADU cost →Building an ADU in Austin costs between $150,000-$350,000 for new construction, with per-square-foot costs averaging $250-$450. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $30,000-$100,000, while prefab/modular ADUs fall in between at $125,000-$300,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | About $1,850-$2,150 in DSD fees for an 800-1,200 sq ft unit (FY2025-26 residential schedule, eff. Oct 1, 2025): $106.72 processing + $896.50-$1,220 plan review + roughly $840-$885 in building, electrical, mechanical, plumbing and energy permits; Austin Energy adds $220-$440. |
| Impact Fees | No City impact fee for an ADU on an already-built lot: the Street Impact Fee applies only to redevelopment adding 10 or more PM-peak trips, and Transportation and Public Works states an ADU on a site with an existing structure owes none. Austin Water capital recovery (impact) fees are assessed per service unit only when a new or larger tap is added: $7,700 combined on lots platted after Oct 1, 2023, $7,200 for 2018-2023 plats, $800-$3,900 by zone for pre-2014 plats. |
| 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. We pass your request to up to 5 local builders serving Austin, where we have them — free, no obligation.
Get Austin builder quotes →Permit fees in Austin are About $1,850-$2,150 in DSD fees for an 800-1,200 sq ft unit (FY2025-26 residential schedule, eff. Oct 1, 2025): $106.72 processing + $896.50-$1,220 plan review + roughly $840-$885 in building, electrical, mechanical, plumbing and energy permits; Austin Energy adds $220-$440.. The review timeline is DSD's published target is 10 business days for the first review of a New Construction application and 7 business days per update (Residential Plan Review page, targets revised July 1, 2026); garage conversions are 5 business days. Time to permit depends on how many review cycles you need., with plan check: 10 business days for the first review (New Construction and Additions), 7 business days for each update submittal, 5 business days for garage conversions: DSD Residential Plan Review targets in force since July 1, 2026. Expedited review is a paid single-session alternative.. Impact fees are No City impact fee for an ADU on an already-built lot: the Street Impact Fee applies only to redevelopment adding 10 or more PM-peak trips, and Transportation and Public Works states an ADU on a site with an existing structure owes none. Austin Water capital recovery (impact) fees are assessed per service unit only when a new or larger tap is added: $7,700 combined on lots platted after Oct 1, 2023, $7,200 for 2018-2023 plats, $800-$3,900 by zone for pre-2014 plats.. Pre-approved plans: None. The City has no pre-approved ADU plan library (Council Resolutions 20200409-080 and 20211209-064 only directed staff to study one, and DSD's ADU page lists none as of Sept 2026). What does exist: fee-based Expedited Residential Plan Review, the AI Pre-Check beta, and free 20-minute Residential Zoning appointments..
| 1-Bedroom Rent | $1,250-$1,850/month |
| 2-Bedroom Rent | $1,600-$2,300/month |
| Annual Rental Income (est.) | $18,600/year |
| Payback Period (est.) | 13.4 years |
| Short-Term Rental | Yes, with a City STR operator's license (Code Ch. 4-23, in force Oct 1, 2025): up to two STRs on a lot of three or fewer units, $836.30 new / $385.30 renewal, two-year term, hotel occupancy tax applies. |
| Overall ROI Estimate | 5-9% gross rent yield (annual rent divided by build cost) |
A typical ADU in Austin generates approximately $18,600 per year in rental income based on average 1-bedroom rents. At an average construction cost of $250,000, the estimated payback period is 13.4 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: $30,000-$100,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $125,000-$300,000.
3. Pre-approved plans — available in Austin, which can save $3,000-$10,000 in design costs and 2-3 months in review time. See which cities offer pre-approved ADU plans.
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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