ADU Rulebook

City · Arizona

ADU rules in Mesa

4 sources

These are the primary sources for accessory dwelling unit regulations in Mesa: 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 detached ADU permitted per lot in any Agricultural, Residential, Commercial and Mixed Use, or Downtown district where a Single Residence is allowed, and on any lot with an existing Single Residence regardless of district. Listed as P (permitted) in the district use tables.

Mesa City Code 11-31-3(A)(1)-(2); Table 11-5-2
Attached or internal ADU
Allowed

One attached ADU permitted per lot under the same applicability rules as detached ADUs. The ADU must have a separate independent entrance and may not have an internal connection to the primary residence.

Mesa City Code 11-31-3(A)(1)-(2), (B)(2)
Maximum size
75% of the primary residence's interior habitable area or 1,000 sq ft, whichever is less (applies to attached and detached)

Habitable area excludes unconditioned storage and parking space. No minimum lot size to establish an ADU.

Mesa City Code 11-31-3(C), (B)(1)
Owner occupancy
Not required

Section 11-31-3 (read in full) contains no owner-occupancy requirement, and A.R.S. 9-461.18(B)(2) prohibits Mesa from requiring any preexisting relationship between the occupants of the primary dwelling and the ADU.

Mesa City Code 11-31-3; A.R.S. 9-461.18(B)(2)
Extra parking
None. No additional parking spaces are required for an ADU, and a garage or carport converted to an ADU does not have to be replaced elsewhere on the lot

The city's ADU FAQ adds that the property must still maintain at least two parking spaces for the primary residence. A.R.S. 9-461.18(B)(3) bars ADU parking requirements or in-lieu fees.

Mesa City Code 11-31-3(G)
Approval process
Permitted use

ADUs are a permitted (P) accessory use in the district land use tables, subject to the standards of Section 11-31-3; only a building permit is required per the city's ADU page (Historic District properties also need a Certificate of Appropriateness).

Table 11-5-2 (Residential Districts) and parallel use tables; Mesa City Code 11-31-3
Rental restrictions
No ADU-specific rental restrictions in the zoning ordinance; long-term rental of the ADU or the main house cannot be prohibited (A.R.S. 9-461.18(B)(1)). Short-term rental (29 days or fewer) is allowed but requires a city Short-Term Rental License under Mesa City Code Title 5, Chapter 15

The city ADU FAQ confirms ADUs may be used as short-term rentals with a license. An ADU may not be sold separately from the primary residence. The second detached ADU allowed on 1+ acre lots must be a restricted-affordable unit rented to households earning up to 80% of area median income.

Mesa City Code 11-31-3(A)(3); Mesa City Code Title 5, Ch. 15; A.R.S. 9-461.18(B)(1)
The fine print: 7 caveats that can change the picture
  • ADUs are not permitted where the property is subject to the AOA 1 or AOA 2 Airport Overflight Areas (footnotes 13-14 to Table 11-5-2; Section 11-19-2), mirroring the airport carve-out in A.R.S. 9-461.18(G)
  • Base allowance is one attached plus one detached ADU per lot; a second detached ADU is allowed only on lots of one acre or more and only if at least one ADU is a deed-restricted affordable unit (up to 80% AMI), per 11-31-3(A)(3)
  • Manufactured homes, RVs, and trailers (including tiny homes on wheels) cannot be used as ADUs (11-31-3(B)(6))
  • New ADUs need only 5 ft side and rear setbacks, but front and street-side setbacks follow the underlying district; conversions of existing conforming or legal non-conforming structures require no additional setbacks (11-31-3(D))
  • Historic District properties must comply with Chapter 74 and obtain a Certificate of Appropriateness before building permit approval (11-31-3(B)(4))
  • HOA CC&Rs can still restrict ADUs; private covenants are outside the city's zoning rules (A.R.S. 9-461.18(C))
  • An ADU may not be built over a public utility easement without written consent of the utilities (11-31-3(H)(3))

Summarized from Mesa'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.

Compare Mesa with 6 nearby cities

ADU regulations

Short-term rental rules

Planning to rent your ADU on Airbnb or VRBO? Mesa 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 Mesa has updated its ordinance, report it and we'll verify against the official source.

Report a correction

Ready to build?

Planning an ADU in Mesa?

Tell us about your project and we'll match you with vetted local designers and builders as we bring them online. No cost, no obligation.

Find a builderEstimate costs first