Austin’s current pages distinguish Additional Dwelling Units, HOME Phase 1 multiple-unit options and HOME Phase 2 small-lot single-family use. Owners should use the live City material because applications and supporting guidance continue to evolve.
Start with the dwelling count and arrangement
Draw every existing and proposed unit. State whether units are attached or detached, which structure is preserved, and whether a subdivision is proposed. This picture is more useful than beginning with “casita” or “guest house.”
Austin defines a dwelling by habitable space, a full bathroom and a sink or dishwasher outside that bathroom. Once a structure is a dwelling, the related zoning, utility, address, occupancy and code requirements apply.
Understand the traditional ADU guidance
The City’s Additional Dwelling Units page describes a separate dwelling on the same property as a single-family home and provides a seven-step planning/permit sequence. It directs applicants to check property requirements and private restrictions, obtain a unique address, submit the residential application, complete review, activate permits, build/inspect and obtain the Certificate of Occupancy.
That page remains a useful project route. HOME Phase 1 changed how some multiple-unit proposals are classified and reviewed, so confirm which standards the City will apply to the current design.
Understand HOME Phase 1
Austin says Phase 1 allows up to three housing units, including tiny homes, on many SF-1, SF-2 and SF-3 properties. Units may be attached or detached in combinations allowed by the applicable standards. The phase also changed the old primary-versus-accessory distinction for certain uses.
“Up to three” is not a parcel approval. Zoning, site, development, building, utilities, deed controls and application requirements remain. Ask the designer to cite the current standard used for dwelling count, size, coverage, height, setbacks, preservation or other claimed benefit.
Understand HOME Phase 2
Phase 2 created a small-lot single-family residential use for certain lots from 1,800 square feet to below the standard 5,750-square-foot threshold. Existing small lots may use a building-permit route; creating new small lots generally involves subdivision or infill work.
This is a one-unit small-lot pathway, not a blanket rule that every small lot can receive an ADU. If the owner is considering subdivision, establish the separate planning, drainage, access, utility and legal work before comparing an ordinary backyard-unit quote.
Check later infill and drainage changes
Austin’s HOME page also describes Residential Infill and Site Plan Lite updates, including drainage treatment for certain re-subdivisions and infill building applications. These details depend on when and how a lot was created and what is proposed.
The project team should identify whether these provisions apply and include required grading or drainage work in the design and budget. Do not assume “streamlined” means no technical work.
Keep private controls in a separate column
Austin warns that deed restrictions or restrictive covenants may affect development. City approval and private enforceability are separate issues. Gather recorded documents and obtain appropriate legal advice when their meaning or enforcement matters.
An HOA statement or neighbor opinion is not a substitute for reviewing the controlling documents. Likewise, a private restriction does not change how the City classifies the permit.
Treat addressing as a project milestone
Every new dwelling in the relevant two-unit or three-unit arrangement needs a unique address. Austin directs owners to Address Management before permit submittal for an ADU.
Assign the request and use the approved address consistently across drawings, utilities, emergency access, delivery planning and closeout.
Decide how the property will operate
The dwelling path affects more than entitlement. Compare:
- resident privacy and access;
- parking and waste handling;
- shared or separate systems;
- future sale or financing questions;
- long-term versus short-term rental goals;
- maintenance and exterior space; and
- phased construction possibilities.
Austin’s ADU page currently places conditions on short-term-rental use for certain newer ADUs and requires a Certificate of Occupancy for licensing. Owners should verify current rules and obtain tax/legal advice rather than designing around an assumed rental strategy.
Put the selected path in every proposal
The feasibility, design and builder documents should state the assumed use, dwelling count, preserved structures, permit route and dated official sources. If a provider prices a different path, the proposals are not comparable.
Use the feasibility guide to turn the selected route into a site and budget test.
Frequently asked questions
Does HOME eliminate the term ADU in Austin?
No. The City still publishes ADU guidance. Phase 1 also removes the old primary/accessory distinction for certain two-unit and three-unit uses. Ask which current route fits the proposal.
Can I split my lot and build three units?
Subdivision and dwelling-count pathways are separate analyses. Confirm eligibility, process, access, drainage and utilities with Austin Development Services and qualified advisers.
Does HOME apply in Round Rock or Cedar Park?
No. HOME amendments are City of Austin rules. Nearby jurisdictions use their own codes and permit systems.
Is a tiny house automatically an ADU?
No. Foundation, mobility, dwelling features, zoning and proposed use matter. Austin provides a separate form/process for certain tiny-house code methods.