Austin ADU permit requirements
Last reviewed: June 22, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in Austin, Texas means pulling a building permit from the local authority that issues it. ArchPermit tracks 13 source-cited requirements (7 required, the rest conditional) for this jurisdiction. Submittals go through Austin Build + Connect (AB+C) online portal. These requirements were last reviewed June 22, 2026; confirm the exact forms and fees with the local permitting authority.
A source-cited checklist of what an ADU (accessory dwelling unit) permit package needs in City of Austin. Every item links to its authoritative source; items that vary are flagged to confirm locally.
Under Austin's HOME initiative (Phase 1, effective Feb 5 2024) up to 3 housing units are allowed on an SF-1/SF-2/SF-3 lot (min lot area 5,750 sf); ADU / 2-unit / 3-unit projects go through the standard residential building-permit track (DSD Residential Plan Review). Each new unit needs a unique address requested in advance. A site plan is NOT required for buildings with two or fewer units; a 3-unit project does require one. Whether the permit is by-right/ministerial is not stated on the official pages; confirm with DSD.
- Austin Energy Building Service Plan Application (BSPA)required
Required for new dwelling units; Austin Energy reviews concurrent with plan review.
source · reviewed 2026-06-22 - Elevation Plansrequired
Exterior elevations showing structure height and the points of measurement.
source · reviewed 2026-06-22 - Existing & Proposed Floor Plansrequired
To scale, with dimensions, ceiling heights, and room labels.
source · reviewed 2026-06-22 - Plot Plan / Site Plan / Survey (to scale)required
Property lines, setbacks, easements, building lines, flatwork/driveways/sidewalks, roof overhangs, parking spaces with dimensions, and trees ≥19" diameter (including adjacent).
source · reviewed 2026-06-22 - Residential New Construction & Addition Permit Applicationrequired
The core completed application form, signed by the owner and applicant; used for ADU / 2-unit / 3-unit projects.
source · reviewed 2026-06-22 - Structural Plans (foundation, framing, brace-wall)required
Foundation plan sealed by a licensed engineer; framing and brace-wall plans designed by a licensed engineer or architect.
source · reviewed 2026-06-22 - Unique Address Assignmentrequired
Each new dwelling unit must have a unique address/building number, requested from Address Management Services before applying.
source · reviewed 2026-06-22 - Acknowledgment of Expired Permitsconditional
Required to resolve any expired permits shown on AB+C for the property (even prior owners') before intake.
source · reviewed 2026-06-22 - Austin Water Service Plan Verification (WWWSPV)conditional
As applicable: required when water demand increases or a new dwelling unit is proposed; stamped by Austin Water.
source · reviewed 2026-06-22 - Demolition Permit Applicationconditional
As applicable: required if any portion of an existing exterior wall, roof, or deck is removed; total demolitions are filed separately.
source · reviewed 2026-06-22 - Owner's Authorization Letterconditional
Required when the application is not signed by the property owner.
source · reviewed 2026-06-22 - Request for Modification / AMOC (triplex)conditional
Required for a triplex (single building, 3 attached units) under HOME; not required for other 3-unit configurations.
source · reviewed 2026-06-22 - Site Plan (3-unit projects only)conditional
A site plan is not required for two or fewer units; a 3-unit project requires a separate site-plan submittal.
source · reviewed 2026-06-22
Austin ADU permit questions
- Do I need a permit to build an ADU in Austin?
- Yes. An accessory dwelling unit (ADU) in Austin requires a building permit. ArchPermit tracks 13 cited requirements for this jurisdiction (7 required, the rest conditional). Always confirm the exact forms, fees, and code edition with the local permitting authority that issues the permit.
- What does an ADU permit package require in Austin?
- Core required items include: Austin Energy Building Service Plan Application (BSPA); Elevation Plans; Existing & Proposed Floor Plans; Plot Plan / Site Plan / Survey (to scale); Residential New Construction & Addition Permit Application; Structural Plans (foundation, framing, brace-wall), plus 1 more. Each requirement links to its authoritative source, and nothing is permit-ready until an independent licensed professional reviews and seals it.
- How are ADU permits submitted in Austin?
- Austin accepts permit submittals via Austin Build + Connect (AB+C) online portal. ArchPermit prepares a draft package you can submit there after a licensed architect reviews and seals it.