Everything homeowners ask about building an ADU in Kansas City — answered with 2026 data.
Yes, ADUs are allowed in Citywide: any lot where a detached dwelling is the principal building, in every zoning district (Sec. 88-305-15-B; Ord. 220698, passed 9-15-2022). Attached ADUs must sit in the rear or side yard; detached ADUs in the rear yard (88-305-15-C.1). in Kansas City, MO. The maximum size for a detached ADU is 800 sq ft floor area or 90% of the house's floor area, whichever is smaller (88-305-15-C.7.d). Footprint also capped at 60% of the house's footprint or 25% of the rear yard, whichever is smaller, and never more than 800 sq ft (C.7.c). An ADU in or on a garage counts the garage's floor area cumulatively (C.4), and all detached accessory buildings together must stay within 88-305-02-E (C.7.f). Attached ADUs can be up to No separate ADU cap in the code: an attached ADU follows the lot and building standards of the principal building. Kansas City has an ADU-friendliness score of 7/10. Check our full Kansas City ADU rules page for complete zoning details.
ADU construction in Kansas City typically costs $90,000-$200,000. The cost per square foot averages $150-$300. Garage conversions are more affordable at $60,000-$150,000, while prefab ADUs cost $75,000-$150,000. Permit fees add Residential building permit = $483 + $1.41 per $1,000 of valuation over $100,000 (City fee calculator; Building Code Sec. 18-20): about $554 on a $150,000 ADU or $624 on $200,000, plus separate electrical, plumbing and mechanical permits. to your budget. See our detailed Kansas City ADU cost guide.
Detached ADUs in Kansas City can be up to 800 sq ft floor area or 90% of the house's floor area, whichever is smaller. Attached ADUs are limited to No separate ADU cap in the code: an attached ADU follows the lot and building standards of the principal building. Junior ADUs (JADUs) have a cap of Not a category in Kansas City's code. The only accessory unit type is the ADU defined in 88-810-005: 'a secondary dwelling unit on the same lot as a principal dwelling unit' that may house an independent household. Maximum height is Detached ADU: the height of the principal building or 25 ft, whichever is less (88-305-15-C.7.a, added by Ord. 230552, passed 6-29-2023). Attached ADU: the district height limit that applies to the house (C.6). Exterior stairs to an upper-level ADU are allowed only on sides facing the interior of the lot (C.8). You are allowed up to One ADU per lot: 88-810-005 defines an ADU as 'a secondary dwelling unit on the same lot as a principal dwelling unit', and the 2022 staff report on a qualifying lot.
Rear setback: 5 ft from all property lines, measured to projections such as eaves (88-305-15-C.7.b). Any other setbacks follow the accessory-structure rules of 88-305-02 (C.7.e). Side setback: 5 ft including projections; on a street side yard, 5 ft or the principal building's setback, whichever is greater (88-305-15-C.7.b). Front setback: A detached ADU must be in the rear yard (88-305-15-C.1 and C.7). An attached ADU sits in the rear or side yard and keeps the house's own front setback (C.1, C.6). Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
None: 'No additional off-street parking is required' (88-305-15-C.3); any parking you choose to build must meet 88-420. Separately, Ord. 260219 (passed 4-9-2026) rewrote 88-420 to drop minimum off-street parking inside the Urban Core (Missouri River to 85th St, State Line Rd to the Blue River) and for houses on lots platted before 9-10-1951. Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Required: the owner must live in either the house or the ADU and record a deed restriction limiting occupancy of one unit to the owner; proof of recording goes to the Director of City Planning and Development before the ADU's certificate of occupancy (88-305-15-C.2). Ord. 220698 ordered a one-year review of this rule; the June 2023 re-enactment (Ord. 230552) kept it unchanged. Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Kansas City is typically Plans Review's published goal for one- and two-family reviews is 7 business days per cycle (resubmittals 10 business days); allow 3-8 weeks to permit including one resubmittal (estimate). The 2x-fee priority review is not offered for one- and two-family projects. Plan check: Included in the building-permit review; the City calculator lists no separate residential plan-check fee. Express review by appointment under IB115; a staked, sealed survey is required with the plans since 1-1-2024 (IB100). Pre-approved plans availability: Yes: 7 free Pre-Approved Housing Master Plans including an 'ADU Over Garage' and a 'Tiny House'. You still submit a site plan and survey, pull each trade permit, and have a mechanical contractor design the HVAC (IB171).
Average ADU rental income in Kansas City: 1-bedroom units rent for $1,100-$1,300/month, 2-bedroom units for $1,350-$1,550/month. Short-term rentals: Yes, only as a 'resident short-term rental': non-resident STRs are prohibited in every R district (88-321, Ord. 230267, passed 5-4-2023). Expected ROI: 6-10% gross (estimate).
The minimum lot size for an ADU in Kansas City is None stated in 88-305-15; the 60%-of-house / 25%-of-rear-yard footprint caps and the 88-305-02-E total accessory-building limit do the work. Since 1-1-2024 a sealed, staked survey must accompany the plans unless the structure is more than 10 ft from every property line (IB100). This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Kansas City, a garage conversion typically costs $60,000-$150,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.
Tell us about your project and we'll pass it to ADU builders serving Kansas City. Free, no obligation — you choose who to work with. We don't have builders in every area yet; if nobody covers yours, we'll email you to say so.
🔒 Your info is secure. We share it only with contractors quoting your project. No spam, no obligation.
Just browsing? Search ADU builders near you by ZIP code.