Accessory Structures in Tucson, AZ: What Residents Actually Need to Know

If you live in Tucson or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. Tucson has 7 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

ADU Rules

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.

Key details: 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.

Building or occupying an ADU without required PDSD permits can trigger stop-work orders and code enforcement under UDC Article 10. Unpermitted structures must be brought into compliance, removed, or legalized through after-the-fact permits, with associated fees.

The rules around adu rules in Tucson lean permissive, but that does not mean anything goes.

Shed Rules

Tucson Unified Development Code (UDC) Section 6.6.2 governs detached residential accessory buildings such as sheds. Detached accessory structures, except accessory dwelling units, may not exceed 12 feet in height. The total gross floor area of all accessory structures may not exceed 50% of the principal structure's gross floor area. A building permit through Planning and Development Services (PDSD) is required for sheds beyond the small unconditioned-storage exemption, and Tucson IRC adoption applies to construction.

Key details: Code Section: Tucson UDC Sec. 6.6.2. Height Limit (detached): 12 ft (except ADUs). Cumulative Floor Area: Up to 50% of principal structure GFA. Building Code: IRC as adopted by City of Tucson. Permit Authority: Tucson Planning & Development Services (PDSD).

Building or placing a shed without a required building permit, exceeding the 12-foot height limit for detached accessory structures, exceeding the 50% cumulative gross floor area cap, or violating the setback requirements of the underlying zoning district violates the UDC and the Tucson Building Code. PDSD code enforcement may issue notices of violation, citations, and orders to correct, and may require relocation, modification, or removal of non-compliant structures.

Garage Conversions

Garage conversions in Tucson must comply with the Building Code (IRC as adopted) and, if used as a separate dwelling, with UDC Section 6.6.3 (Accessory Dwelling Units), as amended October 22, 2024 (effective November 21, 2024) to comply with Arizona HB 2720. ADUs are limited to 75% of the principal dwelling's gross floor area, capped at 1,000 sq ft, with a 650 sq ft floor regardless of principal size. Minimum side and rear setbacks are 5 feet, no on-site parking is required, and the design need not match the principal dwelling.

Key details: ADU Section: Tucson UDC Sec. 6.6.3. Effective Date (HB 2720 update): Nov 21, 2024 (adopted Oct 22, 2024). Max ADU Size: 75% of principal GFA, up to 1,000 sq ft. Minimum ADU Allowance: 650 sq ft regardless of principal size. Min Side/Rear Setback: 5 ft.

Converting a garage to habitable space without the required building, electrical, mechanical, and plumbing permits violates the Tucson Building Code and is subject to citations, stop-work orders, and orders to restore or remove unpermitted work. Operating a converted unit as an ADU without complying with UDC Section 6.6.3 (size cap, 5-foot side/rear setbacks, height, and other dimensional standards) violates the UDC. Using an ADU as a short-term or vacation rental in violation of any applicable owner-occupancy condition allowed by HB 2720 may also be enforceable.

ADU Owner Occupancy

Tucson does not require owner occupancy for ADUs (casitas) under the November 2024 UDC amendments. Arizona HB 2720 prohibits cities over 75,000 from imposing owner-occupancy requirements as a condition of ADU permits or use. HOA CC&Rs may still impose occupancy rules but are subject to ARS 33-1817 limits on unreasonable ADU restrictions.

Key details: Status: Not required (HB 2720). Both Units Rentable: Yes. HOA CC&Rs: Subject to ARS §33-1817. Effective Date: November 21, 2024.

No city enforcement of owner-occupancy. HOA enforcement of CC&R owner-occupancy provisions continues but is subject to challenge under ARS 33-1817. HOA fines typically range $25-$250 per violation depending on the community's enforcement schedule.

The rules around adu owner occupancy in Tucson lean permissive, but that does not mean anything goes.

ADU Permits

Tucson permits ADUs (casitas) under the Unified Development Code as amended November 21, 2024 to comply with Arizona HB 2720. Planning and Development Services Department (PDSD) issues permits ministerially in single-family zones without discretionary hearings. Maximum 75% of primary dwelling gross floor area or 1,000 sq ft, with a 650 sq ft floor regardless of primary size.

Key details: State Law: AZ HB 2720 (effective 2025). City Code: Tucson UDC amended 11/21/2024. Max Size: 75% primary or 1,000 sq ft. Min Floor: 650 sq ft any lot. Parking: Not required.

Building an ADU without permit triggers stop-work orders, double permit fees, and civil penalties under UDC enforcement. Continued violation may face daily fines through PDSD code enforcement. Liens may attach to the property. Construction without inspection voids certificates of occupancy and may impact future financing or sale.

Tucson is more permissive than most cities when it comes to adu permits. That said, there are still limits.

ADU Impact Fees

Tucson charges development impact fees under Arizona Revised Statutes Section 9-463.05 for water, wastewater, parks, transportation, and police. Under HB 2720, impact fees on ADUs in cities over 75,000 must be proportional and may not exceed the impact attributable to the ADU. Tucson Water has separate capacity (hookup) charges where a new meter is installed.

Key details: Fee Authority: ARS §9-463.05. HB 2720: Proportional ADU fees required. Water Meter: Capacity fee if new meter. Categories: Water, wastewater, parks, transport, police.

Impact fees must be paid before building permit issuance. Bypassing permitting to avoid fees triggers double permit fees and civil penalties. Unpaid fees may become liens on the property. Construction without a valid permit prevents certificate of occupancy.

If you are coming from a city with tighter rules, you will find Tucson gives residents more flexibility on adu impact fees.

ADU Rental Restrictions

Tucson permits long-term ADU rentals without registration. Short-term rentals (under 30 days) require a state TPT license from the Arizona Department of Revenue, registration with Pima County Assessor as a residential rental, and a Tucson business license. HB 2720 prohibits ADU-specific bans on rental, but Arizona's STR statute ARS 9-500.39 allows operational regulation.

Key details: Long-Term: No city registration. STR State Statute: ARS §9-500.39. Business License: $95 initial, $70 renewal. TPT License: Required for STR. Noise Limit: 62 dBA nighttime residential.

Operating an STR without TPT license triggers Arizona Department of Revenue audit and back-tax collection with penalties. Unregistered Tucson business license operation carries civil penalties. Noise violations under Code Section 16-31 are civil infractions. HB 2720 prohibits Tucson from outright banning ADU rentals.

The Bottom Line

Compared to many U.S. cities, Tucson gives residents more room on accessory structures. 4 of the 7 rules here are rated permissive. But permissive does not mean unregulated. There are still requirements, and the city does enforce them when violations are reported.

These rules come from Tucson's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.