Tempe is one of the 16 Arizona cities over 75,000 residents covered by HB 2720, so it must allow at least one attached and one detached ADU on single-family lots. The city has permitted ADUs since 2019. As of October 2026, we confirm Tempe's adopted standards with city staff for each address.
What did Tempe propose in its update?
The city's October 2024 announcement of its draft ordinance described these points, which track the state law:
- One attached and one detached ADU per single-family lot, plus one income-restricted unit on lots of an acre or more.
- A maximum of 1,000 sq ft or 75% of the main home, with a larger 2,000 sq ft option proposed for sites of an acre or more.
- No added parking for the ADU, but parking removed from the main house must be replaced.
- Owner residency on site proposed for short-term rental use.
That was a draft. We check the final adopted text before design.
Does Tempe offer pre-approved casita plans?
The City Council approved a design competition in April 2025, according to azfamily.com. Selected designs were to be offered for up to $2,000, and the $2,000 initial plan review fee is waived for homeowners who use one. When a plan suits your lot, this can trim both design cost and review time. We confirm which designs are live when you are ready.
What usually matters on a Tempe lot?
- Older homes. In Tempe's older neighborhoods, the electrical service and the sewer line deserve an early look.
- Irrigation. Where a lot still takes flood irrigation, we locate ditches and valves before placing a foundation.
- Student demand. Near Arizona State University, long-term rental demand is real, and so is HOA and neighbor attention to leasing.
- Existing guest quarters. Tempe noted they can be converted into ADUs with the proper permits.