Under Arizona’s updated statewide ADU (Accessory Dwelling Unit, “casita”) law, effective January 1, 2026, cities such as Phoenix are required to allow accessory dwelling units on all lots where single-family residences are permitted. Homeowners may construct at least one attached ADU and one detached ADU per lot, with each unit allowed up to the lesser of 75% of the primary dwelling’s gross floor area or 1,000 square feet.
On lots of one acre or larger, a third detached ADU may be permitted if one unit is designated as restricted-affordable housing. Local jurisdictions may not impose additional parking requirements, owner-occupancy or familial relationship restrictions, or design standards that are more restrictive than those applied to the primary residence.
Setbacks for ADUs are generally limited to a maximum of five feet, while all applicable building, fire, health, and safety codes remain in effect. These state requirements supersede prior local limitations, including earlier City of Phoenix caps on the number and use of ADUs on single-family lots.
All 13 model show here are permit submittal ready, adjustments to site plan and other requirements by City jurisdiction on the State of Arizona will be needed.
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Disclaimer: This information is provided for general informational purposes only and does not constitute legal Architecture advice. ADU regulations may vary by jurisdiction and are subject to change. Property owners should verify current requirements with the local planning department or consult a qualified design professional before proceeding.
