ADU Permits: Phoenix vs Tempe
How do adu permits rules compare between Phoenix, AZ and Tempe, AZ?
Tempe has fewer restrictions than Phoenix.
Phoenix, AZ
Maricopa County
Phoenix processes ADU permits through Planning and Development under PZC Section 608 (Casita Ordinance) and 2024 Phoenix ADU updates. Arizona HB 2928 (effective 2025) preempts local restrictions in cities over 75,000 residents, requiring ministerial approval for ADUs meeting state standards.
View full Phoenix rules →Tempe, AZ
Maricopa County
Tempe permits accessory dwelling units by right on lots zoned for single-family use under Arizona Revised Statutes section 9-461.18, enacted by HB 2720 in 2024. Tempe (population approximately 185,000) is well over the 75,000 threshold that triggers the state by-right mandate. Tempe's Zoning and Development Code was amended to comply, allowing at least one attached and one detached ADU per single-family lot. Building permits issue through Tempe Community Development.
View full Tempe rules →Key Facts Comparison
| Fact | Phoenix | Tempe |
|---|---|---|
| State Law | AZ HB 2928 (2025) | ARS 9-461.18 (HB 2720) |
| City Code | Phoenix PZC Section 608 | Tempe ZDC + City Code Ch. 8 |
| Max Size | 75% primary or 1,000 sq ft | - |
| Review Type | Ministerial (no hearing) | - |
| Review Time | 10-20 business days | - |
| Units Allowed | - | 1 attached + 1 detached by right |
| Max Side/Rear Setback | - | 5 ft (state cap) |
| Population Threshold | - | Tempe ~185k qualifies (over 75k) |
| Review | - | Tempe Community Development |
Highlighted rows indicate differences between cities.
Phoenix FAQ
Do I need a permit for a Phoenix ADU?
Yes. All ADUs require building permits through Phoenix Planning and Development under PZC Section 608. Under HB 2928, review is ministerial (over-the-counter) without public hearings, but full structural and trade permits are required.
How big can my Phoenix ADU be?
Under Arizona HB 2928, ADUs are limited to 75 percent of the primary dwelling size or 1,000 square feet, whichever is less. Phoenix cannot impose a smaller maximum size than state law.
Tempe FAQ
Can I build a casita in Tempe by right?
Yes. Under Arizona HB 2720 (ARS 9-461.18), Tempe must allow one attached and one detached ADU by right on any single-family lot. Discretionary use permits and public hearings are preempted. You still need building, electrical, plumbing, and mechanical permits through Tempe Community Development.
How close to my property line can the ADU sit in Tempe?
The state statute caps the side and rear yard setbacks Tempe can impose at no more than 5 feet. Tempe's Zoning and Development Code was updated to comply. Front yard setbacks follow the underlying single-family district standards.
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