St. Charles County, MO Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in St. Charles County, MO, also referred to as storage shed, backyard shed, or accessory building regulations, set size limits, setbacks, and when a building permit is required.
Key Facts
- Max size, lots under 1 acre
- 1,200 sq ft
- Max size, 10+ acre lots
- No maximum
- Front setback
- 50 feet
- Side setback
- 7 ft (25 ft on 3+ acres)
- Permit-exempt shed size
- 120 sq ft or less
Summary
St. Charles County caps total accessory-structure square footage by lot size, starting at 1,200 square feet on parcels under an acre, and requires a 50-foot front setback plus 7-foot side and rear yards for sheds and other outbuildings.
1. Maximum total size of all accessory structures (except stables) on any given parcel may not exceed the following limits. a. For parcels less than one (1) acre in size, up to one thousand two hundred (1,200) square feet. ... 3. Minimum front yard of accessory structure. Fifty (50) feet. 4. Minimum side yard of accessory structure. Seven (7) feet, except on lots of three (3) acres, or greater, in which case the minimum side yard shall be twenty-five (25) feet. 5. Minimum rear yard of accessory structure. Seven (7) feet.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4863880; v61 updated 2026-05-11; through 05-11-2026).
Full Breakdown
Under Unified Development Ordinance Section 405.090(E), which governs the county's RR and R1A-R1E single-family districts, combined accessory-structure square footage on a parcel is capped by lot size: 1,200 square feet under one acre, 2,400 for one to three acres, 3,600 for three to five acres, 4,800 for five to ten acres, and no cap at ten acres or more. A shed must sit at least 50 feet from the front property line, 7 feet from side and rear lines (25 feet side yard on lots of three acres or more), and 10 feet from the main house. Under Building Code Section 500.100, a one-story detached shed of 120 square feet or less needs no building permit; anything larger does.
Violations & Fines
The Division of Building and Code Enforcement can order an oversized, unpermitted, or improperly sited shed relocated or removed and require the owner to obtain a retroactive building permit before it can stay.
Frequently Asked Questions
Do I need a permit for a shed in St. Charles County?
How close to my property line can a shed sit?
How big can my shed or accessory building be?
Sources & Official References
Other rules in St. Charles County
How St. Charles County compares: Shed Permit Requirements by City·Compare St. Charles County to another location·View the Missouri accessory structures overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.