Missouri ADU Laws

Complete 2026 guide to accessory dwelling unit regulations

○Local Control Only

📋Quick Facts

Owner Occupancy
May be required
Parking
Set locally
Approval Process
Varies locally

⚠️Key Requirements & Restrictions

  • •No statewide ADU law - entirely local control
  • •St. Louis Board Bill 43 (2023-2024) permits ADUs in all residential zoning districts
  • •Columbia allows ADUs in R-2 zoned residential lots (excluding two overlay districts)
  • •Kansas City and other municipalities have varying local regulations
  • •St. Louis County enforces restrictions on square footage, lot size, setbacks

📖Detailed Analysis

No statewide ADU law - entirely local control with progressive urban areas leading. St. Louis Board Bill 43 permits ADU construction and occupancy in all zoning districts that allow residential use. Columbia allows ADUs in R-2 zoned residential lots but excludes majority R-1 zoned areas. Cities like Columbia are reforming zoning to integrate ADUs into established neighborhoods. Local zoning laws often impose strict conditions on development. Missouri represents urban-led ADU adoption without state intervention, similar to Texas model.

🔗Official Resources

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⚠️ Disclaimer

The information provided on this website is for general informational purposes only and does not constitute legal, financial, or professional advice. ADU laws, regulations, and requirements vary by jurisdiction and change frequently. While we strive to keep this information accurate and up-to-date, we make no representations or warranties of any kind about the completeness, accuracy, reliability, or suitability of this information. Always consult with qualified local professionals, including attorneys, architects, and your local planning department, before making any decisions regarding ADU construction or investment. Use of this information is at your own risk.

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Last updated: February 2026