ADU Permits: Mesa vs Tempe
How do adu permits rules compare between Mesa, AZ and Tempe, AZ?
Mesa and Tempe have similar restriction levels.
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 →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 | Mesa | Tempe |
|---|---|---|
| State Law | AZ HB 2720 (effective 2025) | ARS 9-461.18 (HB 2720) |
| City Code | MZO §11-31-3 (Ord. 5883) | Tempe ZDC + City Code Ch. 8 |
| 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 | - |
| 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.
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.
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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