ADU Rules: Phoenix vs Tempe
How do adu rules rules compare between Phoenix, AZ and Tempe, AZ?
Phoenix and Tempe have similar restriction levels.
Phoenix, AZ
Maricopa County
Phoenix allows up to 2 ADUs per property (one attached, one detached) under Arizona HB 2720 (2024, effective January 2025). A third detached unit is permitted on lots of 1+ acre if one is designated affordable. Each ADU cannot exceed 75% of the main house floor area. On lots up to 10,000 sq ft, ADUs are capped at 1,000 sq ft; larger lots allow up to 3,000 sq ft or 10% of net lot area. Setbacks cannot exceed 5 feet. No additional parking required.
View full Phoenix rules →Tempe, AZ
Maricopa County
Tempe permits Accessory Dwelling Units (ADUs) in residential zones following a 2022 ordinance update. ADUs can be detached, attached, or converted from existing structures. They must meet size, setback, and design standards but do not require additional parking.
View full Tempe rules →Key Facts Comparison
| Fact | Phoenix | Tempe |
|---|---|---|
| Number Allowed | 2 per lot (3 on 1+ acre with affordable) | - |
| Size (small lots) | 1,000 sq ft max on lots up to 10,000 sq ft | - |
| Size (large lots) | 3,000 sq ft or 10% of lot area | - |
| Max vs Main House | 75% of main house floor area | - |
| Setbacks | 5 feet maximum from property lines | 5 feet from side and rear lines |
| Parking | No additional parking required | No additional parking required |
| State Law | HB 2720 (effective Jan 2025) | - |
| Max Size | - | 75% of primary home or 1,000 sq ft |
| STR Use | - | Not permitted for rentals under 30 days |
| Design | - | Must match primary dwelling style |
Highlighted rows indicate differences between cities.
Phoenix FAQ
Tempe FAQ
Can I build an ADU in Tempe?
Yes. Tempe allows one ADU per single-family lot, up to 1,000 square feet or 75% of the primary dwelling. A building permit is required.
Can I rent out my ADU on Airbnb?
No. Tempe's ADU ordinance prohibits using ADUs as short-term rentals (under 30 days). Long-term rentals are permitted.
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