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