From paperwork to inspection

• Do I need a permit?

  Yes, you will need a building permit as well as trade permits for mechanical, electrical, plumbing, and right-of-way if you are working in the street (driveway apron, adding parking, etc).

• I understand the code has changed in Austin regarding how big ADUs can be – can you summarize the current regulations?

  The previous land development code - which one can still develop under - limited ADUs to 0.15 FAR (FAR = floor-to-area ratio - floor area of your structure as compared to the size of your lot) or 1100 square feet, whichever is smaller. For instance, if you had a 6000sf lot, your ADU would be limited to 900 square feet.

  With the addition of the HOME Amendment Phase 1, landowners have a lot more options regarding secondary and now tertiary structures. In practical terms, the new limit for a single structure is .4 FAR or 2300sf, whichever is larger.

• How close to my property line can the ADU be?

  In Austin, the typical side yard setback is 5'-0" and 10'-0" at the rear.

• How many stories can my ADU be?

  If you are developing under the previous code the height limit is 32’ while the HOME Amendment allows for up to 35’. The number of stories depends on the design and configuration of the home, but three stories are allowed.

• How far away from my house does the ADU have to be?

  The prescriptive requirement of 10’ separation difference between the main house and adu has been removed from the code and now the prevailing Building and Fire Codes dictate structure spacing. While you can build structures closer together than 10’, it should be noted that openings will be limited, and fire-rated materials will be required on the facades that face each other. If you have room to set your structures at least 10’ apart, that would be considered best practice.

• Does an ADU require driveway access?

  No, Austin has removed all its requirements for off-street parking.

General information, not legal or code advice — Austin’s rules change, and what applies to your lot depends on the property. Ask us or the City for specifics.