ADU Permits: Gilbert vs Phoenix
How do adu permits rules compare between Gilbert, AZ and Phoenix, AZ?
Gilbert and Phoenix have similar restriction levels.
Gilbert, AZ
Maricopa County
Gilbert processes ADU permits through Development Services. Arizona HB 2720 (signed May 2024, effective January 1, 2025) preempts most local ADU restrictions in cities over 75,000 residents and codifies ADU rules at ARS 9-461.18. Gilbert (population over 280,000) must allow at least one attached and one detached ADU per single-family lot by right.
View full Gilbert rules →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 →Key Facts Comparison
| Fact | Gilbert | Phoenix |
|---|---|---|
| State Law | ARS §9-461.18 (HB 2720) | AZ HB 2928 (2025) |
| City Code | Gilbert LDC Chapter 5 | Phoenix PZC Section 608 |
| Review Type | By right (no Use Permit) | Ministerial (no hearing) |
| Max Side/Rear Setback | 5 ft | - |
| Review Time | 10-20 business days | 10-20 business days |
| Max Size | - | 75% primary or 1,000 sq ft |
Highlighted rows indicate differences between cities.
Gilbert FAQ
Do I need a Use Permit for a Gilbert casita?
No, not since January 1, 2025. ARS 9-461.18 (HB 2720) preempted Gilbert's prior Use Permit requirement. ADUs are now a permitted use by right on single-family lots, though you still need building, electrical, plumbing, and mechanical permits through Development Services.
How many ADUs can I have on my Gilbert lot?
At least one attached and one detached ADU on any single-family lot. Lots one acre or larger qualify for a third detached ADU if one of the units is designated as a restricted-affordable dwelling unit under ARS 9-461.18.
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.
Compare other topics
See how Gilbert and Phoenix compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool