Jackson County, MO Accessory Structures: ADU Rules (2026)

Jackson County exercises zoning authority over its unincorporated territory through the Unified Development Code, originally consolidated in 2020 and adopted under the Jackson County Charter. The UDC establishes a hierarchy of residential and agricultural districts: the Residential Estates (RE) district is intended for low-density residential use on lots of two or more acres as a transition between rural and suburban areas; the Residential Ranchette (RR) district is intended for very low density use with a minimum lot size of five acres so property owners can keep a limited number of large animals and accessory buildings; and the Agricultural (AG) district allows farming and farm-related accessory uses. A detached accessory dwelling unit is not a separately defined district-wide permitted use in standard residential zones — applicants typically pursue a conditional use permit or use variance through the Planning and Development Division (303 W. Walnut, Independence). Building permits in unincorporated areas are issued under Jackson County Code Chapter 54 (Building Code), which adopts the 2018 International Building Code, 2018 International Residential Code, and related International Codes. Inside cities, the local zoning code controls — for example, Kansas City's Zoning and Development Code (Chapter 88) and Independence's Code govern ADUs separately. Missouri has not enacted a statewide ADU preemption statute, so the operative rule is always the controlling local zoning ordinance.