ADU rules in Mesa, AZ — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
Mesa allows ADUs by right in all single-residence districts under MZO Section 11-31-3 (updated by Ordinances 5883 and 5950). No minimum lot size. Maximum 1,000 sq ft or 75% of primary residence. Garage conversion parking replacement eliminated.
Mesa permits internal, attached, and detached accessory dwelling units (ADUs) by right in all single-residence zoning districts under MZO Section 11-31-3, as updated by Ordinance No. 5883 (2024) and Ordinance No. 5950 (July 2025). There are no minimum lot size requirements to establish an ADU. The interior habitable area cannot exceed 75% of the primary residence or 1,000 square feet, whichever is less, compliant with HB 2720 (Jan 2025) which requires cities over 75,000 to allow ADUs by right with up to 2 per lot. ADUs require separate independent entrances and water, sewer, and electric utilities. Existing structures converted to ADUs require no additional setbacks — a major 2025 amendment that eliminated covered parking replacement requirements for garage conversions. Manufactured homes, RVs, and trailers cannot serve as ADUs. ADUs in Historic Districts must comply with Chapter 74. HOA covenants prohibiting casitas can preempt the city's zoning. Mesa has been noted for its generous ADU rules within the East Valley.
Building ADUs without permits or exceeding size limits is a zoning violation. Non-compliant structures may face correction orders. Unpermitted ADUs cannot be legally rented. Contact Development Services at 480-644-4273.
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Side-by-side rule comparisons with other cities in Maricopa County.
See how other cities in Maricopa County handle adu rules.
See how Mesa's adu rules rules stack up against other locations.
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