What's Required in Kansas City
- ADUs are allowed only on lots whose principal building is a detached house.
- Attached ADUs go in the rear or side yard; detached ADUs go in the rear yard.
- The owner must live in the house or the ADU and record a deed restriction before the certificate of occupancy.
- A detached ADU may be no taller than the house or 25 feet and must be 5 feet from all property lines.
- Detached ADU footprint is the smaller of 60% of the house footprint or 25% of the rear yard, up to 800 square feet.
- Floor area is the smaller of 800 square feet or 90% of the house's floor area.
- The unit needs a full kitchen, a full bathroom and living and sleeping space to count as an ADU.
- Attached and internal ADUs are designed to the IRC's duplex requirements and must meet the adopted energy code.
- No additional off-street parking is required.
Can You Build an ADU in Kansas City?
Yes. Section 88-305-15 of the Zoning and Development Code, adopted in 2022 and amended in 2023, permits accessory dwelling units on any lot with a detached house as the principal building. An attached ADU must be in the rear or side yard; a detached ADU must be in the rear yard. The catch is ownership: the owner must live in either the house or the ADU and record a deed restriction saying so, and proof of recording is due before the city issues the ADU's certificate of occupancy. No extra off-street parking is required. This page covers Kansas City, Missouri (KCMO). Kansas City, Kansas, across the state line, is a separate city with its own permit office and rules.
Kansas City ADU Rules by Scenario
| What you are doing | City filing | Rule |
|---|---|---|
| Converting a basement or attic into an ADU | Building and trade permits; built as a duplex | IB170 |
| Attached ADU addition | Building permit with plans; house setbacks apply | Zoning 88-305-15-C |
| Detached ADU in the rear yard | Building permit with plans and sealed survey | 88-305-15-C; IB100 |
| ADU over or attached to a detached garage | Allowed; floor area limits combine | 88-305-15-C |
| Renting both units with the owner living elsewhere | Not allowed | 88-305-15-C |
| ADU on a lot whose main building is a duplex or apartment | Not allowed | 88-305-15-B |
| Unit without a full kitchen and full bath | Not an ADU; regular accessory structure rules | IB170 |
How Big Can an ADU Be in Kansas City?
An attached ADU follows the house's own lot and building standards. A detached ADU may be no taller than the house or 25 feet, whichever is less, and must be set back 5 feet from all property lines, projections included. Its footprint is capped at 60% of the house's footprint or 25% of the rear yard, whichever is smaller, and never more than 800 square feet. Floor area is capped at 800 square feet or 90% of the house's floor area, whichever is smaller. All detached accessory buildings together may cover no more than 40% of the rear yard, and exterior stairs to an upper-level unit must face the interior of the lot. Information Bulletin 170 adds that an ADU needs a kitchen with sink, stove or oven and refrigerator, a full bathroom (a half bath does not count), and living and sleeping space. Attached and internal ADUs are designed as a duplex under the IRC, and plans must meet the energy code.
How Much Does an ADU Permit Cost in Kansas City?
The city's fees follow the one- and two-family valuation table in Section 18-20(b)(2), with a separate permit for each trade, each priced on its own value. Above $100,000 the building permit is $483 plus $1.41 per additional $1,000; below that it is $58 plus $4.33 per $1,000 over $2,000. A $250,000 detached ADU pays $483 + 150 × $1.41 = $694.50 for the building permit, plus $157.59 each for $25,000 of electrical and $25,000 of plumbing and $135.94 for $20,000 of mechanical work: $1,145.62. An $80,000 basement conversion pays $58 + 78 × $4.33 = $395.74, plus $83.98, $83.98 and $75.32 for $8,000, $8,000 and $6,000 of trade work: $639.02. These are city permit fees only; water and sewer connection charges and the cost of recording the deed restriction are separate, so ask KC Water and the county recorder.
Who Can Build It?
A contractor building or enlarging a dwelling, or a detached accessory building over 400 square feet, needs a city Residential Building Contractor license. An owner who lives in a single-family home may pull the permits and act as general contractor, but licensed electrical, plumbing and mechanical subcontractors must pull their own permits. The plan review goal is seven business days.
How to Get a ADU Permit in Kansas City
Confirm the lot qualifies
The principal building must be a detached house and you must plan to live in one of the two units.
Size the unit
Check the 800 sq ft caps, the 60% and 25% footprint limits, the 25 ft height limit and 5 ft setbacks for a detached unit.
Prepare plans and survey
Follow IB100 and IB170: full plans, energy code sheets, and a sealed survey for new structures and additions.
Apply and pay in CompassKC
File the building permit and separate trade permits; each fee follows its own value from the valuation table.
Record the deed restriction
Record the owner-occupancy restriction and give the city proof before it issues the ADU's certificate of occupancy.