ADU Rulebook

City · Arizona

ADU rules in Tempe

5 sources

These are the primary sources for accessory dwelling unit regulations in Tempe: the city's own zoning code, planning department pages, and permit guides. Start here before talking to anyone: the rules below are what your permit reviewer will apply.

Rules at a glance

Detached (backyard) ADU
Allowed

One attached and one detached ADU allowed on any lot under one acre with a single-family dwelling; a third ADU is allowed on lots of one acre or more if one ADU is a deed-restricted affordable unit.

ZDC Section 3-402(C)(1)
Attached or internal ADU
Allowed

One attached ADU allowed per lot alongside one detached ADU; permitted in all residential districts where the property contains a single-family dwelling.

ZDC Section 3-402(B), (C)(1)
Maximum size
1,000 sq ft of interior habitable area or 75% of the main residence's gross floor area, whichever is less; on lots of 1 acre or more, 2,000 sq ft or 75% of the main residence, whichever is less

Gross floor area means interior habitable area, excluding garages, carports, and exterior storage. Bedrooms capped at three in a 1,000 sq ft ADU; no bedroom limit on lots of one acre or more.

ZDC Section 3-402(C)(2), (C)(4)
Owner occupancy
Not required

No owner-occupancy requirement for building an ADU or renting it long-term; owner occupancy requirements apply only when the ADU is used as a short-term or vacation rental.

ZDC Section 3-402(E)(1)
Extra parking
None; no additional vehicle parking is required for an ADU

If ADU construction removes or modifies a required parking space for the main residence, that space must be replaced in a location authorized by the Community Development Director.

ZDC Section 3-402(C)(3)
Approval process
Permitted use

ADUs are a permissible use by right in all residential districts when the property contains a single-family dwelling, subject to building, fire, and health codes; standard building permits apply.

ZDC Section 3-402(B)
Rental restrictions
ADU may be rented or leased independently of the main residence; short-term and vacation rental use is permitted subject to Tempe City Code Chapter 16a, Article X and owner occupancy requirements; the ADU cannot be subdivided onto its own lot or sold separately

A third ADU on lots of one acre or more must be deed-restricted affordable, rented only to households at or below 80% of area median income, with annual compliance reporting.

ZDC Section 3-402(A)(2), (E), (G)
The fine print: 5 caveats that can change the picture
  • Size, bedroom, and unit-count allowances scale with lot size: lots of one acre or more get a 2,000 sq ft cap, no bedroom limit, and a possible third ADU if one unit is deed-restricted affordable (rented at or below 80% AMI with annual reporting).
  • ADUs are allowed only on properties containing a single-family dwelling, though this applies in all residential districts including multi-family zones; in multi-family districts an ADU expanded beyond the size cap converts the property to multi-family standards.
  • Setbacks (5 ft rear/side minimum), height, and lot coverage defer to the underlying district standards in Sections 4-202, 3-401, and 3-420, so envelope limits vary by zone.
  • Existing guest quarters count against the one-attached-plus-one-detached ADU allowance; converting guest quarters to an ADU terminates any rental-restriction covenant.
  • Section 3-402(A)(1) states that A.R.S. 9-461.18 controls over any conflicting local provision.

Summarized from Tempe's ordinance text, read July 2026; every row links the code section it came from. Rules often vary by zone and lot, so treat this as orientation, not a permit determination, and confirm with the planning department before you commit to a design.

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ADU regulations

Short-term rental rules

Planning to rent your ADU on Airbnb or VRBO? Tempe regulates short-term rentals separately; check these before counting on nightly rental income.

Arizona statewide law also applies

Arizona sets baseline ADU rights at the state level. Where local rules are stricter than state law allows, state law usually wins, so both are worth reading.

See Arizona statewide rules

Spotted something outdated?

Zoning codes change. If a link is dead or Tempe has updated its ordinance, report it and we'll verify against the official source.

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