ADU Permits: Gilbert vs Mesa
How do adu permits rules compare between Gilbert, AZ and Mesa, AZ?
Mesa has fewer restrictions than Gilbert.
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 →Mesa, AZ
Maricopa County
Mesa permits ADUs by right in all single-residence districts under Mesa Zoning Ordinance Title 11, Section 11-31-3, as updated by Ordinances 5883 and 5950 to comply with Arizona HB 2720. Internal, attached, and detached ADUs are allowed. Maximum 75% of the primary residence interior habitable area or 1,000 sq ft, whichever is less. No minimum lot size and no additional parking required.
View full Mesa rules →Key Facts Comparison
| Fact | Gilbert | Mesa |
|---|---|---|
| State Law | ARS §9-461.18 (HB 2720) | AZ HB 2720 (effective 2025) |
| City Code | Gilbert LDC Chapter 5 | MZO §11-31-3 (Ord. 5883) |
| Review Type | By right (no Use Permit) | - |
| Max Side/Rear Setback | 5 ft | - |
| Review Time | 10-20 business days | - |
| Max Size | - | 75% primary or 1,000 sq ft |
| Min Lot Size | - | None |
| Parking | - | Not required |
| ADUs Per Lot | - | 1 attached + 1 detached by right |
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.
Mesa FAQ
Do I need a permit for a Mesa ADU?
Yes. All ADUs require building permits through Mesa Development Services. Under HB 2720 and MZO Section 11-31-3, review is ministerial (over-the-counter) without public hearings. Full structural, electrical, mechanical, and plumbing trade permits are required.
How many ADUs can I build on my Mesa lot?
At least one attached and one detached ADU are permitted by right on any lot where a single-family dwelling is permitted, with no minimum lot size. On lots of at least one acre, a third ADU (second detached) is permitted only if deed-restricted as affordable to households at 80% AMI.
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