ADU rules for Unincorporated St. Louis
Accessory Dwelling Unit (ADU) Rules for Unincorporated St. Louis, MO
Is your property eligible for an ADU?
# of Properties
114,722
Owner-occupied
82%
Zoning districts
106
Avg Home Value
$288,159
Median Lot Size
0.23 acres
Avg Income
$89,635
Residential Types:
115,206 housing units
Single Family
90%
Apts (4+ units)
10%
Zoning Districts:
125,007 parcels · 106 districts
R3
28%(35,349)
R4
21%(26,762)
R2
18%(22,866)
R5
16%(20,246)
Other
16%(19,784)
ADU Rules
What can you build in Unincorporated St. Louis, MO?
Unincorporated St. Louis, MO follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.
Eligibility
- –Internal / Attached ADU: Not addressed in the local bylaw
- –Detached ADU: Not addressed in the local bylaw
Parking
- –No ADU-specific min/max; Director determines required parking when no minimum; reductions up to 15% in form-based districts and within 1,000 ft of transit (not ADU-specific).
What's allowed on your lot?
These are the municipality-wide rules. What's allowed on a specific property also depends on state laws, setbacks, floor area ratio, lot coverage, environmental constraints, topography, and other property-specific factors. Search your address on FutureLot to see what's allowed on your property.
Check my propertyHow can we help you?
Get matched with trusted local builders
Understand what's allowed on your property
Learn the key rules and size limits for ADUs
Is your property eligible for an ADU?
ADU rules in other Missouri municipalities
Rules change at the town line. Check the municipality your property is actually in.
St. Louis County
Browse addresses by ZIP in Unincorporated St. Louis
6312920,049 addresses6312316,517 addresses6312512,799 addresses6312811,508 addresses631469,045 addresses630347,751 addresses630217,609 addresses630267,184 addresses631386,228 addresses631365,914 addresses630335,563 addresses630314,182 addresses631142,177 addresses631371,823 addresses630111,639 addresses631261,560 addresses