Tucson, AZ Accessory Structures: Garage Conversions (2026)

A garage conversion in Tucson is regulated as a building matter under the Tucson Code (which adopts the International Residential Code with local amendments) and, if the converted space is used as a separate dwelling unit, as a zoning matter under UDC Section 6.6.3 (Residential Uses), specifically the Accessory Dwelling Unit provisions. Any conversion of a garage to habitable space requires building, electrical, mechanical, and plumbing permits issued by Planning and Development Services. Plans must demonstrate compliance with the IRC as adopted by Tucson, including ceiling height, egress, light and ventilation, smoke and carbon monoxide alarms, energy/insulation, and electrical and mechanical work. If the converted space includes its own kitchen, bathroom, and sleeping area and is intended as an independent unit, it must also comply with the ADU regulations adopted by Mayor and Council on October 22, 2024 and effective November 21, 2024 (adopted to bring Tucson into compliance with Arizona HB 2720). Under those amended rules in UDC Section 6.6.3, an ADU is limited to 75% of the gross floor area of the principal dwelling, not to exceed 1,000 square feet; an ADU of up to 650 square feet is permitted regardless of the size of the principal dwelling. The minimum side and rear yard setbacks for an ADU are 5 feet. Vehicular parking is not required to be provided for an ADU. ADUs are not required to match the exterior design, roof pitch, or finishing materials of the single-family dwelling on the same lot. Properties with one or more ADUs are exempted from commercial site plan requirements, multifamily designation, commercial development standards, and (other than construction-related repairs) street improvements. Garage conversions used as ADUs are one of the allowed ADU formats (interior conversion, attached, or detached). Owner-occupancy is generally not required for long-term-rental ADUs under HB 2720; however, for ADUs used as short-term or vacation rentals constructed on or after September 14, 2024, Arizona law allows the city to require the property owner to reside on the premises. Setback, height, and other UDC standards continue to apply to the underlying converted structure.