ADU Rules: Green Valley vs Tucson
How do adu rules rules compare between Green Valley, AZ and Tucson, AZ?
Tucson has fewer restrictions than Green Valley.
Green Valley, AZ
Pima County
Pima County allows accessory dwelling units (ADUs or guest houses) in certain residential zones subject to zoning code requirements. ADUs must be subordinate to the primary dwelling, meet setback and height limits, and comply with building code. ADUs built after September 14, 2024 and used as STRs require owner occupancy on the property.
View full Green Valley rules →Tucson, AZ
Pima County
Tucson allows up to two accessory dwelling units (casitas) per single-family lot under UDC §6.6.3, with a third permitted on lots one acre or larger if one unit is restricted-affordable. Amendments effective November 21, 2024 brought Tucson into compliance with Arizona HB 2720 (ARS §9-461.18) by eliminating parking requirements and reducing minimum side and rear setbacks to five feet.
View full Tucson rules →Key Facts Comparison
| Fact | Green Valley | Tucson |
|---|---|---|
| Zones | CR-3, CR-5, SR, SH, GR-1 | - |
| Size Limit | Typically 50% of primary dwelling | - |
| Building Permit | Required from Development Services | - |
| STR Rule | Post-Sep 2024 ADUs: owner must reside on property | - |
| Parking | 1 additional off-street space | - |
| Code Section | - | Tucson UDC §6.6.3 |
| State Mandate | - | ARS §9-461.18 (HB 2720, eff. 1/1/2025) |
| Max Size | - | 75% of principal, up to 1,000 sq ft |
| Guaranteed Minimum | - | 650 sq ft on any qualifying lot |
| Side/Rear Setback | - | 5 ft minimum |
| ADUs Per Lot | - | Up to 2 (3 on 1+ acre with affordable) |
| Parking Required | - | None (eliminated Nov 21, 2024) |
| Effective Date | - | November 21, 2024 |
Highlighted rows indicate differences between cities.
Green Valley FAQ
Can I build a guest house on my property?
Yes, in most residential zones on larger lots (CR-3 and above). The ADU must be subordinate to the primary dwelling, meet setback requirements, and have a building permit from Pima County Development Services.
Can I rent my ADU as a short-term rental?
ADUs with certificates of occupancy issued after September 14, 2024 may only be used as STRs if the property owner lives on the property. ADUs built before that date are not subject to this restriction.
Tucson FAQ
How many ADUs can I build on my Tucson lot?
Up to two ADUs are allowed per single-family lot under UDC §6.6.3. If your lot is one acre or larger, you may build a third detached ADU provided at least one unit on the property is deeded as a restricted-affordable dwelling unit serving households at or below 80% of area median income.
Do I need to provide parking for my Tucson casita?
No. As of the November 21, 2024 amendments, Tucson eliminated the parking requirement for ADUs. This change brought the city into compliance with Arizona HB 2720 (ARS §9-461.18), which prohibits municipalities over 75,000 residents from requiring additional parking for accessory dwelling units.
What is the largest ADU I can build in Tucson?
An ADU is limited to 75% of the principal dwelling's gross floor area, capped at 1,000 square feet. However, every qualifying lot is guaranteed at least 650 square feet regardless of the principal dwelling size, so smaller homes still allow a 650 sq ft casita.
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