ADU rules in Kansas City

The codified zoning code (Unified Government Code Chapter 27, Article VIII, Supp. 52) defines an accessory dwelling unit only as "a dwelling unit that is located over a garage on the same lot or parcel as the primary residential building" (Sec. 27-340) and lists ADUs as an accessory use in no standard residential district: the R-1, R-1(B), R-2 and R-2(B) accessory-use list in Sec. 27-609 and the R-3 through R-M list in Sec. 27-610 contain no dwelling unit of any kind. The use reaches the ground in only two settings. First, the Narrow Lot Design Guidelines (February 18, 2008), incorporated by reference in Secs. 27-454(d)(3)b and 27-455(c)(3) for new residences east of I-635 on narrow lots in R-1, R-1(B), their RP-1 and RP-1(B) planned equivalents and districts that borrow those standards, allow an "Accessory Unit" (a granny flat over a garage, attached or detached, toward the rear) as a building type paired with the new house. Second, the TND traditional neighborhood design planned district lists an accessory unit, which there may also be a single-story detached unit not tied to a garage, as a building type, one per main structure (Sec. 27-471(h)(1)a, (j)(1)b). Planning staff told the City Planning Commission on 8-10-2026 that ADUs "can only be built with new construction using narrow lot design guidelines" and have "no designated approval pathway" elsewhere, so a backyard unit behind an existing house on an ordinary lot has no path under the operative text. A new Sec. 27-624 that would allow detached, attached, interior and converted ADUs in every district that allows a residential use was recommended 7 to 0 by the Planning Commission on 9-14-2026 and heard by the Board of Commissioners on 10-1-2026; as of 10-8-2026 it had not been published in The Wyandotte Echo or codified, so it is recorded in the caveats rather than as the value.

The same Sec. 27-340 definition says the unit "can be attached or detached from the primary residential building" but must sit over a garage, toward the rear of the lot and never in the front yard, so an attached garage apartment qualifies only in the two settings that allow any ADU at all: a new narrow-lot house built under the Narrow Lot Design Guidelines east of I-635 (Secs. 27-454(d)(3)b, 27-455(c)(3)) or a TND district (Sec. 27-471(h)(1)a). Basement, attic and other interior conversions of an existing house are not accessory dwelling units under the codified definition and have no approval path; a converted detached garage without new construction over it likewise falls outside the definition. The pending Sec. 27-624 would add express "interior" (basement, attic, interior garage or room with a separate entrance), "attached" and "converted" ADU types alongside detached units.

Sec. 27-340 caps every accessory dwelling unit at "a maximum square footage equal to 50 percent of the main structure's finished space excluding garages and basements"; the Narrow Lot Design Guidelines repeat the same 50 percent rule for the Accessory Unit building type, and the TND district repeats it for accessory units and adds that they "shall not exceed the height of the primary structure" (Sec. 27-471(h)(1)a, (k)(1)). No minimum ADU size is written; the house itself must have at least 864 sq ft of habitable floor area in R-1 and 750 sq ft in R-1(B) (Secs. 27-454(d)(4), 27-455(c)(4)). The Board-packet version of the pending Sec. 27-624(d)(2) would set the cap at 50 percent of the primary dwelling unit's gross floor area or 1,000 sq ft, whichever is greater, with the ADU never exceeding the primary dwelling's gross floor area, and (d)(3) would cap detached and converted units at the lower of the district height limit and the house's height.

No codified provision requires the owner to live on the lot in order to build or keep an accessory dwelling unit. The code defines an "Accessory dwelling unit, primary" as "the accessory dwelling unit that the property owner resides within" (Sec. 27-340) only so the short-term rental section can tell owner-occupied from investor arrangements. Owner occupancy matters only when the ADU or the house is rented for fewer than 30 days: an "actively owner-occupied" property whose owner is present on site for the whole stay may use the administrative review path (Sec. 27-623(b)(1)), while any other short-term rental needs a special use permit (Sec. 27-623(c)). The pending Sec. 27-624(h) would state expressly that "The property owner is not otherwise required to reside on the property."

Sec. 27-340 ends the ADU definition with "Accessory units must maintain existing parking requirements," and no section adds a space for the unit itself. The requirement being preserved is the district minimum for the house: two off-street spaces per single-family dwelling, at least one in a garage or carport, in R-1 (Sec. 27-454(e)), and two spaces in R-1(B) (Sec. 27-455(d)), so an over-garage unit cannot displace the garage spaces that satisfy it. The pending Sec. 27-624(e) would read "No additional off-street parking is required for ADUs," and the companion SB 418 compliance ordinance heard the same night would cut the R-1 minimum to one space per single-family dwelling.

No discretionary hearing is written for an ADU anywhere it is possible, but the path differs by setting and is absent in most of the city. For a new narrow-lot house east of I-635, the Accessory Unit is approved with the house: planning staff review the design against the Narrow Lot Design Guidelines, which Secs. 27-454(d)(3)b and 27-455(c)(3) incorporate by reference, and the Director's Interpretation of 9-27-2022 treats that compliance as a staff determination made at building permit (the Director may grant limited exceptions such as alley access); the review is mandatory on undeveloped lots east of I-635 that are under the district minimums (R-1 lots under 7,150 sq ft; R-1(B) lots under 50 ft of frontage or 5,000 sq ft) and optional on other undeveloped lots there. In a TND district, accessory units are a by-right building type but the lot's final plans are approved by the Design Review Board under the planned-district procedure (Sec. 27-471(u)). On an existing house outside those settings there is no permit to apply for, because the use is not listed. The pending Sec. 27-624(g) would make every ADU a building permit only ("no separate administrative review is required") with a complete application "deemed approved unless the application is denied within 30 days of receipt" under the By-Right Housing Development Act.

Nothing in Chapter 27 bars renting an accessory dwelling unit for 30 days or more, but every rented unit, including a rented unit on an owner-occupied property, needs a rental dwelling license before occupancy (Secs. 19-226, 19-227(a)); licenses expire April 30 each year and the unit is inspected before issuance (Secs. 19-231, 19-234). Short-term rental (under 30 days) is an accessory use in any district that allows a residential use, and Sec. 27-623(a)(2) says an ADU "may also be used as a short-term rental instead of or in addition to an allowed primary residence." An actively owner-occupied property whose owner is present on site for the whole stay may use administrative review, under which the house's partial unit and the full ADU may be rented concurrently, or the whole house may be rented while the owner stays in the ADU (Sec. 27-623(b)); any other arrangement, including an investor-owned ADU, needs a special use permit, and no more than one parcel per street block may hold one (Sec. 27-623(c)(1)b). Deed, plat and HOA prohibitions control (Sec. 27-623(a)(3)), and the owner collects lodging taxes (Sec. 27-623(d)). The pending Sec. 27-624(h) would keep ADU short-term rentals subject to Sec. 27-623 and the recitals describe rental income as a purpose of the ordinance.