Wyandotte County, KS Accessory Structures: ADU Rules (2026)

The Unified Government of Wyandotte County/Kansas City, Kansas defines an accessory dwelling unit in the zoning code's general definitions at Sec. 27-340 as a dwelling unit located over a garage on the same lot as the primary residence, which can be attached to or detached from the main house. The unit must sit toward the rear of the parcel; the definition flatly forbids placing one in the front yard, regardless of whether it is built over an attached or a freestanding garage. Size is capped at 50 percent of the main structure's finished living space, specifically excluding garages and basements from both sides of that calculation, so a homeowner has to measure the primary house's actual finished area before sizing the accessory unit.

The rule also requires the property to maintain whatever off-street parking already existed before the accessory unit went in; adding an ADU cannot be used as an excuse to eliminate driveway or garage parking. This definition governs Kansas City, Kansas and unincorporated Wyandotte County; Bonner Springs and Edwardsville keep their own municipal codes and are not covered by Chapter 27. Before construction, the property owner still needs a building permit under Sec. 27-363 and a certificate of occupancy under Sec. 27-364 from the building official, who enforces the zoning article per Sec. 27-362. An ADU that is later rented out short-term is subject to the separate owner-occupancy and licensing standards in Sec. 27-623.