Austin, TX · Updated 2026
Austin ADU Permits: Fees, Timeline & Process
HOME Phase 2 rules — expanded zoning, 2,500 sq ft min lot, and up to 3 units per lot.
Quick Answer
Austin ADUs: $125K–$300K
Permits: $5K–$15K · Updated April 2026
Austin ADU Permitting: Overview
Austin's HOME (Home Options for Middle-income Empowerment) Phase 2 initiative dramatically expanded ADU opportunities in 2024. ADUs are now allowed in SF-1, SF-2, and SF-3 zoning districts (previously limited to SF-3 only), the minimum lot size was reduced from 5,750 to 2,500 square feet, and homeowners can build up to three units per lot.
The city processes ADU permits through the Austin Build + Connect (AB+C) online portal and ProjectDox for document management. No owner-occupancy is required, and parking mandates have been eliminated citywide. The maximum ADU size increased to 1,350 sq ft or 0.15 FAR, whichever is smaller.
Permit Fees Breakdown
Total permitting costs in Austin typically range from $5,000–$15,000 depending on ADU type, size, and site conditions.
| Fee Type | Amount | Notes |
|---|---|---|
| Plan Review Fee | $1,500–$5,000 | Based on project scope and valuation |
| Building Permit | $2,000–$6,000 | Calculated at permit activation |
| Trade Permits | $500–$1,500 | Electrical, plumbing, mechanical |
| Impact Fees | $0–$3,000 | May apply based on location |
| Water/Wastewater | $2,000–$5,000 | Connection fees for new service |
| Inspection Fees | Included | Part of building permit |
Fees are estimates based on typical ADU projects. Contact Austin permitting for exact quotes. See our full permit fees guide for comparison across cities.
Zoning & Requirements
- ADUs allowed in SF-1, SF-2, and SF-3 zoning districts
- Minimum lot size: 2,500 sq ft (reduced from 5,750)
- Up to 3 total units per lot under HOME Phase 2
- Maximum ADU size: 1,350 sq ft or 0.15 FAR, whichever is smaller
- ADU + main house cannot exceed 40% lot coverage
- No parking required for ADUs (citywide elimination)
- No owner-occupancy requirement
- Deed restrictions may still apply — check your property
Step-by-Step Permit Process
Verify property eligibility
Check zoning at austintexas.gov to confirm your lot is SF-1, SF-2, or SF-3 and meets the 2,500 sq ft minimum. Also check for deed restrictions.
Request a new address
ADUs require a unique address or building number. Submit through Address Management Services before applying.
Create AB+C account
Register on the Austin Build + Connect (AB+C) Portal. This is required for fee payment and application management.
Submit building permit
Apply through the Residential Plan Review webpage. Upload stamped construction drawings, site plan, and all required documentation.
Pay plan review fees
Residential Intake staff will verify documents and invoice plan review fees through your AB+C account.
Plan review (8–16 weeks)
Coordinate with assigned staff to work through any corrections and reach approval.
Pay permit fees & activate
Once approved, pay permit fees and activate the building and trade permits through AB+C.
Construction & inspections
Schedule inspections through AB+C: foundation, framing, trades, and final. Permits expire after 181 days without inspection.
Certificate of Occupancy
Final building inspection pass triggers CO issuance by the Building Inspector.
Key Regulations & Laws
HOME Phase 2 (2024)
Expanded ADU zoning to SF-1 and SF-2 districts, reduced minimum lot size to 2,500 sq ft, and allows up to 3 units per lot.
No Parking Mandate
Austin eliminated parking requirements for ADUs citywide, freeing up yard space and reducing costs.
No Owner-Occupancy
Austin does not require property owners to live on-site to build or rent an ADU.
Permit Expiration
Active permits expire after 181 days without a scheduled or completed inspection. Each passed inspection extends the expiration another 180 days.
Frequently Asked Questions
How much do ADU permits cost in Austin?
Permit fees typically range from $3,500–$12,000 depending on project scope. Plan review fees are invoiced first, followed by permit activation fees. Total permitting costs including utility connections run $5,000–$15,000.
How long does the ADU permit process take in Austin?
Expect 8–16 weeks from application to approval. Complex sites or review backlogs can extend this. The full project from design to completion typically takes 10–18 months.
What zoning allows ADUs in Austin?
ADUs are now allowed in SF-1, SF-2, and SF-3 zoning districts under HOME Phase 2. The minimum lot size is 2,500 square feet.
Can I build more than one ADU in Austin?
Yes. HOME Phase 2 allows up to 3 total units per qualifying lot, meaning you could have a main house plus two additional dwelling units in some cases.
Your Next Steps
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