What's Required in Austin
- HOME Phase 2 (2024/2026) reduces the minimum lot size to 2,000 square feet for single-family residential lots.
- ADUs are permitted by-right in all single-family zones (SF-1, SF-2, SF-3) with up to 3 units allowed on many lots.
- Maximum ADU size is 1,100 square feet or 15% of the total lot area, whichever is less.
- Detached ADUs require a 4-foot side setback and a 10-foot rear setback from property lines.
- Each unit requires a unique address or building number obtained via Address Management Services.
- No additional off-street parking is required for ADUs anywhere in the City of Austin.
How Much Does an ADU Permit Cost in Austin?
Budget $1,500–$4,000 for the Austin permit itself (valuation-based), issued by the City of Austin Development Services Department — but treat that as the entry fee, not the total. ADUs are full dwelling units, so the permit stack usually includes building, electrical, plumbing, and mechanical trade permits, plus plan review. One local note: includes plan review (50–65% of base), building permit, and potential parkland dedication fees. Get an itemized fee estimate from the department before finalizing your budget; the spread between a simple conversion and a new detached build is wide.
ADU Size Limits and Zoning Rules in Austin
Before drawing plans, check the two gates that sink most ADU projects: size and zoning. Size ceilings vary by lot and ADU type (attached, detached, or conversion), so confirm your specific configuration. Other recorded conditions: no additional off-street parking is required for ADUs anywhere in the City of Austin. Setbacks, height limits, and utility connections layer on top of those rules. The City of Austin Development Services Department can confirm what your specific lot allows — worth doing before you pay for architectural drawings rather than after.
How to Get a ADU Permit in Austin
Step 1: Zoning Verification
Use the Property Profile tool to verify your lot's zoning (SF-1, SF-2, SF-3) and ADU eligibility.
Step 2: Address Request
Submit a request to the Address Management Services to obtain a separate unit address before applying for a permit.
Step 3: Professional Plans Submission
Upload IRC-compliant structural, site, and energy plans to the AB+C portal for Residential Plan Review.
Step 4: Fee Payment
Pay the plan review fees ($277 minimum for circulation) once intake staff verifies your documentation.
Step 5: Full Inspection Sequence
Schedule Foundation, Framing, Rough MEP, and Final inspections to receive a Certificate of Occupancy.