Everything homeowners need to know about building an accessory dwelling unit in Austin - size limits, setbacks, permits, and how the city's HOME Initiative reshaped what's possible on a single-family lot.
Last verified: September 2026
8/10 · Very ADU-friendly
1,100 sq ft*
Max ADU size
35 ft
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes the City of Austin's Land Development Code (Title 25) and the 2023-2024 HOME Initiative amendments for general reference - it is not legal advice. Regulations change; always confirm current requirements with the Austin Development Services Department (DSD) before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new build or garage conversion)
The lesser of 1,100 sq ft or 15% of the lot area
35 ft, subject to compatibility standards near existing single-family homes
Must meet setback and total site-coverage limits; typically sits behind the primary home
Attached / internal (above-garage, addition)
Sized within the primary structure's footprint, subject to the same overall size cap
Generally matches the primary structure
True basements are uncommon in Central Texas due to shallow bedrock, so most "attached" ADUs are additions or above-garage conversions
Allowed zoning districts
Texas has no statewide ADU mandate, so Austin's own code is what governs. ADUs are allowed on single-family zoned lots (SF-1, SF-2, SF-3) citywide, plus additional zones opened up by the HOME Initiative's 2024 amendments. Minimum lot size for newly subdivided lots dropped as low as 1,800 sq ft in some cases. Confirm your parcel's zoning district and eligibility with DSD.
Additional standards
Setbacks, parking & other rules
Setbacks
Generally 5 ft from side and rear property lines for a detached ADU, with a minimum 10 ft separation from the primary house; exact setbacks vary by zoning overlay and lot configuration - confirm your parcel's specifics with DSD
Parking
No off-street parking required for smaller ADUs (roughly under 550 sq ft) or for lots near qualifying transit corridors; larger ADUs may require one additional space
Units per lot
Up to 3 residential units total per lot under the HOME framework (for example, the primary home plus two additional units, which can include an ADU), subject to lot size and site constraints
Owner-occupancy
Not required. Austin removed its owner-occupancy requirement in February 2024 as part of HOME Phase 1
Building code
Must meet the City of Austin's locally amended residential building code
Short-term rental
ADUs built or converted after October 1, 2015 may not be used as a short-term rental for more than 30 days per calendar year
Ordinance history
How Austin's ADU rules got here
2015ADUs formally codified. Austin's original accessory dwelling unit ordinance took effect, setting the baseline secondary-apartment rules the city built on for the next decade.
2023HOME Initiative approved. Austin City Council approved the Home Options for Middle-income Empowerment (HOME) Initiative in December 2023, the biggest rewrite of the city's single-family land development rules in decades.
2024HOME Phase 1 takes effect. Effective February 5, 2024, minimum lot sizes dropped, up to three units became allowed on many single-family lots, and the citywide owner-occupancy requirement for ADUs was removed.
2024HOME Phase 2 takes effect. Minimum lot size for newly subdivided lots fell as low as 1,800 sq ft, with further adjustments to compatibility and site-development standards.
2025Statewide ADU bill fails. Texas Senate Bill 673, which would have set statewide ADU standards and limited cities' ability to restrict them, died in the Legislature in June 2025 - leaving Austin's local rules as the operative standard.
Worth knowing: even with HOME's zoning changes now in place, local reporting points to construction cost, financing, and impact fees as bigger remaining barriers for many Austin homeowners than the zoning code itself.
Permit process
How Austin ADU permitting works
1
Pre-application zoning check
Confirm your lot's zoning district, overlays, and ADU eligibility with DSD before you design.
2
Prepare your plans
Site plan, floor plans, elevations, and structural details showing the ADU and how it meets the size and setback limits.
3
Get a new address
Each ADU needs its own address or building number from Austin's Address Management Services before you submit for a building permit.
4
Submit through Austin Build + Connect
File electronically through the AB+C portal; the system routes your plans to building, zoning, fire, environmental, and drainage review at the same time.
5
Plan review & revisions
Expect at least one round of comments; review commonly runs roughly 2-4 months depending on completeness and project complexity.
6
Permit issuance & inspections
Once approved, pull your building permit, begin construction, and schedule standard framing, plumbing, electrical, and final inspections.
Total permit-related costs, including plan review, building permit, and impact fees, commonly range from roughly $3,000 to $15,000 depending on project size and utility needs. Fees and timelines are approximate - confirm current figures with DSD.
Budgeting
What it costs to build an ADU in Austin
Garage conversion
Roughly $80,000-$150,000, generally the least expensive path since the shell already exists
New detached ADU
Roughly $150,000-$400,000+, reflecting Austin's higher land and labor costs at an estimated $250-$400 per sq ft
Attached / above-garage addition
Typically less than a detached new build since it shares a wall, foundation, or roofline with the existing house; true basement conversions are uncommon given Central Texas soil conditions
Permit & impact fees
Roughly $3,000-$15,000 total depending on project size, including plan review, building permit, and water/wastewater/transportation impact fees
These are general ranges from local contractor estimates and regional reporting, not quotes - lot conditions, utility access, and finish level drive the final number. Many contractors suggest adding roughly 15-20% on top of a base quote for permitting, utility hookups, and design fees.
Before you apply
Tips for a smooth approval
Confirm eligibility before you design. Not every lot qualifies for the full HOME framework - a pre-application check with DSD confirms your zoning, overlays, and any deed restrictions.
Get your address assigned early. You'll need a unique address for the ADU before submitting for a building permit - request it from Address Management Services well before you're ready to submit.
Budget for impact fees separately. Water, wastewater, and transportation impact fees are billed on top of plan review and building permit fees, and can add thousands of dollars.
Check for deed restrictions. Some Austin subdivisions carry private deed restrictions that limit ADUs regardless of what the zoning code allows - verifying is your responsibility, not the city's.
Plan your unit count and parking together. If you're aiming for the full three units HOME allows, work through the site plan with a designer early - lot coverage and setback limits fill up fast.
FAQ
Common questions
Do I need to live on the property to build an ADU in Austin?
No. Austin removed its owner-occupancy requirement in February 2024 as part of the HOME Initiative, so you can build and rent out an ADU without living on site.
How many units can I have on one lot?
Up to three residential units total under HOME, subject to lot size, setbacks, and site-development limits - confirm what your specific lot can support with DSD.
What's the maximum size for an ADU?
The lesser of 1,100 sq ft or 15% of the lot area.
Do I need extra parking for an ADU?
Often not. HOME removed parking mandates for smaller ADUs and for many properties near transit corridors; larger units may still require one off-street space.
Can I rent my ADU out short-term?
ADUs built or converted after October 1, 2015 may not be used as a short-term rental for more than 30 days per calendar year.
How long does the permit process take?
Plan review commonly runs roughly 2-4 months depending on application completeness and project type; applications are submitted through the Austin Build + Connect (AB+C) portal.
How much does an ADU cost to build in Austin?
Garage conversions typically run $80,000-$150,000, while new detached units commonly run $150,000-$400,000 or more given Austin's land and labor costs, based on local contractor estimates and regional reporting.
Does Texas have a statewide ADU law?
No. A bill that would have set statewide ADU standards and limited cities' ability to restrict them (Senate Bill 673) died in the Legislature in June 2025, so Austin's local rules are what currently govern.
What changed with the HOME Initiative?
HOME reduced minimum lot sizes, allowed up to three units on many single-family lots, and removed the owner-occupancy requirement for ADUs, rolled out in two phases during 2024.
