ADU rules in Arizona
Representative cities: Phoenix, Tucson.
ADU permit rule
Permit requiredGenerally allowedcity authority
Fee basis
Valuation-based; set by the issuing city.
Typical timeline
Phoenix ~30–90 days; Tucson ministerial review since the Nov 2024 UDC amendment.
Setback
Phoenix: 5 ft rear, 3 ft side (R1 zones); Tucson per the Unified Development Code.
Area threshold
Phoenix max 1,000 sq ft; Tucson allows ≥1 ADU per lot (up to 2 on lots with an existing home).
Exempt if
None — an ADU (casita) always requires a building permit.
Go / no-go
allowed
Arizona has no statewide ADU law. Phoenix and Tucson both allow ADUs by local ordinance; Tucson review is ministerial under state HB 2720.
ADU official sources: City of Phoenix — Planning & Development (Residential) · City of Tucson — Permit Exemptions & ADU
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Frequently asked questions
Do I need a permit to build an ADU in Arizona?
Per Arizona rules, an ADU is "yes" for a permit and the authority is "city". Arizona has no statewide ADU law. Phoenix and Tucson both allow ADUs by local ordinance; Tucson review is ministerial under state HB 2720. Always confirm with the issuing building department.
How big can an ADU be in Arizona?
Area threshold: Phoenix max 1,000 sq ft; Tucson allows ≥1 ADU per lot (up to 2 on lots with an existing home).
What are the ADU setbacks in Arizona?
Setback: Phoenix: 5 ft rear, 3 ft side (R1 zones); Tucson per the Unified Development Code.
How much does an ADU permit cost in Arizona?
Fee basis: Valuation-based; set by the issuing city.
State-wide sources: City of Phoenix — Planning & Development Department · City of Tucson — Planning & Development Services · Arizona Legislature — ARS §36-1681 (Pool Barriers)
Plan the ADU numbers for Arizona
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Rental ROI and payback
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Financing comparison
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Does your ADU need a permit?
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