St. Charles County, MO Fence Regulations: Retaining Walls (2026)
Key Facts
- Permit-exempt height
- Not over 4 ft, footing to top of wall
- Permit trigger
- Any height if wall supports a surcharge
- Permit fee
- $100 or cost-based fee, whichever greater
- Violation fine
- Up to $500 per day, misdemeanor
- Stop-work penalty
- Up to $250 administrative penalty
- Appeal body
- County Building Commission, Section R112.1
- Enforcing agency
- Division of Building and Code Enforcement
Summary
St. Charles County exempts retaining walls up to four feet from a building permit under Residential Code Section R105.2, measured from the bottom of the footing to the top of the wall. Walls above that height, or any wall supporting a surcharge, need a permit from the Division of Building and Code Enforcement and cost $100 or the construction-cost fee formula, whichever is greater.
R105.2 Work exempt from permits. Exemptions from permit requirements of this code shall not be deemed to grant authorization for any work to be done in any manner in violation of the provisions of this code or any other laws or ordinances of this jurisdiction. Permits shall not be required for the following: Building:
1. Other than storm shelters, one-story detached accessory structures, provided that the floor area does not exceed two hundred (200) square feet (18.58 m2).
2. Fences not over seven (7) feet (2,134 mm) high.
3. Retaining walls that are not over four (4) feet (1,219 mm) in height measured from the bottom of the footing to the top of the wall, unless supporting a surcharge.
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 the Residential Code for One- and Two-Family Dwellings, adopted at St. 2, Item 3. Any retaining wall taller than four feet, or a shorter wall backing a slope, driveway or other load, needs a full permit from the Division of Building and Code Enforcement. 1, construction documents must be prepared by a registered design professional when the Building Official requires it, and special site conditions can force a mandatory engineered design. 020(A)(2)(e)(8), is $100 or the estimated construction cost multiplied by the county's Permit Fee Multiplier, whichever is greater.
6, anyone who starts wall construction before the permit issues owes an added fee on top of the permit cost, though rough grading under 5,000 square feet and simple stakeouts are excepted. 4 makes it a misdemeanor to build, alter or occupy in violation of an approved permit or the Building Official's directive, punishable by a fine of up to $500, with each day the violation continues counted as a separate offense. 2, the owner or contractor must pay an administrative penalty of up to $250 before work resumes. 100.
Violations & Fines
Building a retaining wall over four feet without a permit, or ignoring conditions on an issued permit, is a misdemeanor under Section R113.4: a fine of up to $500, with each day the violation continues counted as a separate offense. If county inspectors issue a stop-work order under Section R114.2, work must halt immediately and the responsible party owes an administrative penalty of up to $250 before the Building Official authorizes work to resume.
Frequently Asked Questions
Do I need a permit for a retaining wall in St. Charles County?
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Sources & Official References
Other rules in St. Charles County
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