ADU Rules in St. Louis, MO — 2026 Guide
Check if your St. Louis property qualifies for an ADU in 20 seconds
St. Louis ADU Rules at a Glance
St. Louis has limited ADU support. Here is what you need to know.
- St. Louis does not have a comprehensive ADU ordinance.
- Accessory structures may be permitted in certain zoning districts with a conditional use permit.
- Carriage houses in historic districts sometimes qualify as ADU-like conversions.
- No statewide ADU legislation exists in Missouri.
What ReadyPermit Checks for St. Louis Properties
Enter any St. Louis address and get an instant ADU feasibility analysis covering:
Zoning Compliance
Verify your St. Louis lot is zoned for ADU construction under current MO and local rules.
Setbacks & Coverage
Check required setbacks, lot coverage limits, and height restrictions for your specific parcel.
ADU Size Limits
Calculate the maximum ADU square footage allowed based on your lot size and primary dwelling.
Permit Requirements
Understand what permits and approvals St. Louis requires before you can break ground.
Flood & Hazard Zones
Identify if your property falls in a flood zone, fire zone, or other hazard overlay.
Lot & Parcel Data
Pull parcel boundaries, lot dimensions, and existing structures from county records.
Check Your St. Louis Property Free
Enter your address below. In under 20 seconds you will know if your St. Louis lot qualifies for an ADU — no phone calls, no waiting.
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