ADU rules in Avondale, AZ — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
Avondale's Zoning Ordinance Section 28-33 permits at least one attached and one detached ADU on any single-family lot. ADUs are capped at 75 percent of the main home's floor area or 1,000 square feet, whichever is less, with five-foot side and rear setbacks, no extra parking, and no owner-occupancy requirement.
Avondale adopted detailed accessory dwelling unit rules in Section 28-33 of its Zoning Ordinance, mirroring Arizona's statewide ADU law (A.R.S. 9-461.18) that applies to municipalities over 75,000 people. With a population near 96,600, Avondale falls squarely under that statute. Under Section 28-33(a)(1), lots smaller than one acre may have one attached ADU and one detached ADU; lots of one acre or more may have one attached and up to two detached ADUs if one detached unit is restricted-affordable. Section 28-33(a)(3)(A) limits an ADU to 75 percent of the gross floor area of the existing single-family dwelling or 1,000 square feet, whichever is less. Setbacks under Section 28-33(a)(3)(D) are a minimum of five feet from rear and side property lines, with the front yard following the underlying district standard. Section 28-33(a)(5) provides that no additional parking space or in-lieu fee may be required for a new ADU. The ordinance does not impose owner occupancy: Section 28-33(a)(2)(C) allows either the main dwelling or any ADU to be separately leased as long-term rental housing. Mobile homes, RVs, and other movable habitable space may not be used as an ADU.
Building an ADU that exceeds the size cap, violates the five-foot setbacks, or uses a prohibited mobile home or RV is a zoning violation enforced by Avondale Code Compliance. ADUs require permits through Avondale Development Services, and unpermitted construction can trigger stop-work orders and after-the-fact permit requirements.
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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.
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