Austin ADU

ADUs in Austin

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ADUs, accessory dwelling units, also known as granny flats, casitas or guest houses, are defined by the City of Austin as "a separate dwelling unit on the same property as a single-family home that is smaller in size."

Requirements for this type of home

Requirements for the lot

Currently, only areas in an SF-3 district are zoned for two detached dwelling units in a residential lot. In addition to being limited to SF-3 zoned lots, the city requires the lot to be a minimum of 5,750 sq. ft. There must be a minimum of 10 feet of separation on all sides between the "main" home and the ADU (or the unit must be above a detached garage.) Last but not least location-wise, impervious cover for the site may not exceed 45%, and building cover for the site may not exceed 40%.

Requirements for the ADU

ADUs can be a maximum of 1,100 sq. ft. or a floor-to-area ratio of 0.15, whichever is smaller. Secondary units are limited to a height of 30 feet and two stories. The second story cannot exceed 550 sq. ft.

Additional requirements

ADUs can't be used as a short-term rental for more than 30 days in a calendar year. A parking space must be provided for the ADU in addition to one for the "main" home.

Links to City of Austin Resources

City of Austin ADU explainer can be found here.

Check zoning on your favorite Austin neighborhoods by exploring this map.

Review existing city ordinances at this link.