5 county-level rules, plus city-specific rules for 4 cities in Pima County, Arizona.
Verified from official government sources
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.
Pima County allows storage sheds as accessory structures in all residential zones. Sheds under 200 square feet and not on a permanent foundation typically do not require a building permit. Larger sheds require permits and must meet setback requirements. All sheds must comply with wind and tie-down requirements for the Sonoran Desert climate.
Converting a garage to living space in unincorporated Pima County requires a building permit from Development Services. The conversion must meet residential building code for habitable space including insulation, ventilation, egress windows, and ceiling height. Replacement off-street parking may be required by the zoning code.
Pima County allows carports as accessory structures in residential zones. Open carports (roof only, no enclosed walls) under 200 square feet may be exempt from building permits. Larger carports require permits and must meet setback and wind-load requirements for the monsoon climate.
Pima County permits tiny homes as accessory dwelling units under the 2024 Zoning Code update for unincorporated areas. Tiny homes on wheels are classified as recreational vehicles and cannot serve as permanent dwellings. Site-built or modular tiny homes on foundations must meet IRC building standards and obtain standard building permits through Pima County Development Services.
4 cities in Pima County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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