Tucson, AZ Accessory Structures: ADU Rules (2026)
ADU rules in Tucson, AZ, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- ADUs permitted per single-family parcel
- 2 (1 on duplex lots)
- Max ADU size
- Lesser of 75% of house or 1,000 sf
- Flat size allowance regardless of house size
- Up to 650 square feet
- ADU side/rear setback
- 5 feet
- Parking requirement
- None required for ADUs
- Bonus 3rd ADU
- Lots over 1 acre with a deed-restricted unit
Summary
Tucson's UDC allows up to two accessory dwelling units per single-family parcel, one on a duplex lot, without counting them against density limits or requiring extra parking. Each ADU is capped at 75% of the principal home's floor area or 1,000 square feet, whichever is smaller, though any ADU may reach 650 square feet regardless of house size.
An accessory dwelling unit may be used as living quarters... Two accessory dwelling units are permitted per parcel developed with a Family Dwelling as defined in Section 11.3.7.A., with the exception of a Multifamily Development. A parcel developed with a duplex is permitted one accessory dwelling unit... 1. Accessory dwelling units are not subject to maximum residential density standards per Section 6.3.4... 3. Vehicular parking is not required to be provided for accessory dwelling units... 5. An accessory dwelling unit is limited to 75% of the gross floor area of the principal dwelling, not to exceed 1,000 square feet of gross floor area. An accessory dwelling unit may be up to 650 square feet of gross floor area, regardless of the size of principal dwelling. 6. The minimum side and rear yard setback for an accessory dwelling unit is five feet.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-150: Current through June 23, 2026).
Full Breakdown
UDC Sec. B lets an accessory dwelling unit include a kitchen, bedrooms, bathrooms, and a sitting room, provided it isn't the dominant use of the property. Two accessory dwelling units are permitted per parcel developed with a Family Dwelling, except on a Multifamily Development site; a duplex parcel is limited to one. A lot larger than one acre can add a further ADU beyond that if at least one unit on the property is a deed-restricted affordable dwelling unit under Sec. 2, with proof required as a condition of the building permit.
ADUs are exempt from Tucson's maximum residential density standards, and vehicular parking is not required for them. A new ADU structure must use a high-albedo (over 60 SRI) or other cool-roof technology meeting the ICC Green Construction Code. Size is capped at 75% of the principal dwelling's gross floor area, not to exceed 1,000 square feet, but any ADU may reach 650 square feet regardless of the main house's size. The minimum side and rear yard setback for an ADU is five feet, and detached ADUs cannot sit in the buildable area spanning the full lot width between the house and the front lot line, except for small shade structures or carports under 400 square feet.
ADUs need not match the exterior design, roof pitch, or materials of the main house, but must follow the landscaping standards in UDC Sec. C.
Violations & Fines
An ADU built beyond the permitted count, oversized, or missing its required setback is a UDC violation subject to Article 10 enforcement. The Zoning Administrator can issue a correction notice, cite the owner under Chapter 8 of the Tucson Code, or refer the matter to the City Attorney for a restraining or abatement action. An affordable-unit ADU that loses its deed restriction forfeits the density bonus that authorized the extra unit.
Frequently Asked Questions
How many ADUs can I build on a Tucson single-family lot?
How big can a Tucson ADU be?
Do I need extra parking for an ADU in Tucson?
Sources & Official References
Other rules in Tucson
How Tucson compares: Easiest Cities to Build an ADU·Compare Tucson to another location·View the Arizona accessory structures overview
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ADU Rules in Nearby Cities
How other cities in Pima County handle adu rules.