Everything homeowners ask about building an ADU in Kansas City — answered with 2026 data.
Yes, ADUs are allowed in Any lot with a detached single-family dwelling as the principal building (citywide, all residential districts) — Sec. 88-305-15 in Kansas City, MO. The maximum size for a detached ADU is 800 sq ft floor area max; footprint also capped at 60% of the main home's footprint or 25% of the rear yard, whichever is smaller. Attached ADUs can be up to 800 sq ft or 90% of the principal dwelling's floor area, whichever is smaller. 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 $100,000-$300,000. The cost per square foot averages $150-$300. Garage conversions are more affordable at $80,000-$150,000, while prefab ADUs cost $90,000-$180,000. Permit fees add $1,500-$5,000 typical, valuation-based (estimate) - Confirm against the current KCMO fee schedule 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 max; footprint also capped at 60% of the main home's footprint or 25% of the rear yard, whichever is smaller. Attached ADUs are limited to 800 sq ft or 90% of the principal dwelling's floor area, whichever is smaller. Junior ADUs (JADUs) have a cap of Not a separate category in Kansas City's code. Maximum height is Height of the principal building or 25 ft, whichever is less. You are allowed up to 1 ADU per lot on a qualifying lot.
Rear setback: 5 feet from all property lines (including projections). Side setback: 5 feet including projections; street-side: 5 ft or the principal building's setback, whichever is greater. Front setback: Detached ADUs must be in the rear yard; attached ADUs follow the main home's front setback. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
No additional off-street parking required. 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 — owner must live in the main home or the ADU, recorded as a deed restriction. 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 4-12 weeks plan review (estimate) - Confirm with City Planning & Development. Plan check: 4-8 weeks. Pre-approved plans availability: Yes — free Pre-Approved Housing Master Plans, including an ADU-over-garage design (trade permits still required).
Average ADU rental income in Kansas City: 1-bedroom units rent for $1,100-$1,300/month, 2-bedroom units for $1,300-$1,500/month. Short-term rentals: Restricted — owner-occupied registration required citywide; whether the ADU itself can be the STR is ambiguous in code (Type 1 rules reference the principal building) — confirm with the city. Expected ROI: 6-8% annual return.
The minimum lot size for an ADU in Kansas City is None stated - the footprint/rear-yard percentage caps do the work. 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 $80,000-$150,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.