ADU Rules in Austin, TX (2026)
ADU rules, permit requirements, size limits, and fees for Austin, TX. Source-cited from official municipal code.
Whether ADUs are allowed in Austin, TX has not been confirmed — see the official source before proceeding.
Whether Austin, TX permits accessory dwelling units (ADUs) has not been confirmed from an official source. ADUs — also called granny flats, in-law units, or secondary suites — are secondary housing units on a single-family or multifamily lot. Contact the local building department at (512) 978-4000 to verify current ADU rules before proceeding, as regulations may have changed since this data was last reviewed.
ADU Size Limits
ADU Size Limits in Austin: Detached ADU: size varies by zoning — see official source (max height: varies — see official source). Attached ADU: size varies by zoning — see official source.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | See official source | See official source |
| Attached ADU | See official source | See official source |
Permit Fees
ADU Permit Fees in Austin: Plan check fee: Varies. Building permit fee: Varies. Impact fees: None. School fees: None or N/A. Total estimated permit cost: Varies.
| Fee Type | Amount |
|---|---|
| Plan Check | $300–$2,000 |
| Building Permit | Based on construction value — typically $1,000–$4,000 |
| Impact Fees | Varies significantly — Austin charges Transportation, Water/Wastewater, Drainage impact fees |
| School Fees | None |
| Total Estimate | See official source |
Permit Timeline
Austin ADU Permit Timeline: Permit timeline has not been confirmed — contact the department for current processing times. Apply through the local building department online permit portal. Phone: (512) 978-4000.
Setback Requirements
ADU Setback Requirements in Austin: Front setback: follows zone standard. Side setback: no minimum. Rear setback: no minimum.
Parking Requirements
Parking Requirements: Parking requirements have not been confirmed — see official source.
Restrictions & Requirements
- Secondary apartment must be on same lot as main residence
- Minimum lot size requirements by zone (SF-2 requires 5,750 sqft minimum)
- Impervious cover limits by watershed — development cannot exceed basin-specific limits
- Tree preservation requirements may limit placement — Heritage Trees (19+ inch diameter) cannot be removed
- Secondary apartment unit cannot be separately conveyed (sold separately) from main lot
- Short-term rental of secondary apartment requires STR license
How Many ADUs Are Allowed?
Number of ADUs Allowed in Austin: Single-family lots: not confirmed — see official source. Multifamily properties: not confirmed — see official source.
- Single-Family Lots
- 1 secondary apartment per lot (plus HOME initiative allows up to 3 total units)
- Multifamily Properties
- Multiple units allowed per zoning in MF zones
Statewide Preemption
ADU Preemption
We could not confirm a statewide ADU preemption statute for Texas.
View Texas preemption detailsFrequently Asked Questions
Can I build an ADU in Austin?
Yes. Austin, TX allows accessory dwelling units. On a single-family lot you can build 1 secondary apartment per lot (plus HOME initiative allows up to 3 total units).
How big can an ADU be in Austin?
The maximum size for a detached ADU in Austin is 1,100 square feet.
How long does it take to get an ADU permit in Austin?
The typical ADU permit timeline in Austin is Austin DSD building permit: typically 2-4 months plan review. Austin has electronic permit review (Austin Build + Connect portal). Construction 4-12 months.. Total estimated permit fees are $3,000–$15,000 total fees including impact fees.
Do I need extra parking for an ADU in Austin?
Austin parking rules for ADUs: 1 parking space required per secondary apartment unit unless within one-quarter mile of CapMetro urban rail station. Reduced parking available in transit-oriented development zones.
Do I have to live on-site to have an ADU in Austin?
Owner-occupancy requirement in Austin: No owner-occupancy requirement for secondary apartments in Austin. Owner does not need to reside on property.
Source: Austin City Code Title 25, Section 25-2-774 — Secondary Apartments; HOME Ordinance 2023-05-18. Last verified April 3, 2026. View source