Lee's Summit, MO Accessory Structures: ADU Rules (2026)

IV-1, properties of half an acre or larger zoned AG, RDR, RLL, R-1 or RP-1, or any property approved through the Preliminary Development Plan process. Only one ADU is allowed per single-family lot, and it must be accessory to a principal single-family home on the same lot; it can be built as an internal conversion of existing living space, an addition to the house, a conversion of a detached garage, or new detached construction. Development standards require the ADU to sit at least 6 feet behind the front of the principal structure and at least 20 feet from the rear lot line, though that setback does not apply to an ADU built inside the existing house; side setbacks match whatever the zoning district requires for the principal structure.

The unit cannot exceed 1,000 square feet or 50 percent of the principal structure's floor area, whichever is less, except that lots under 15,000 square feet in Old Downtown Lee's Summit cap the ADU at 500 square feet or 50 percent of the principal structure, and the ADU cannot push total impervious lot coverage above 60 percent, hold more than two bedrooms, or exceed the height of the main house. One additional off-street parking space with access to a public or private street is required beyond what the principal home already needs, and converting a garage into an ADU is barred unless replacement parking is provided elsewhere on the lot.

At permit application the owner must attest to owner-occupancy of the property, and ongoing owner-occupancy of either the primary home or the ADU is mandatory, though the Director may grant a temporary one-year waiver for documented employment, illness, or similar circumstances. e.