St. Clair County, IL Fence Regulations: Retaining Walls (2026)
Key Facts
- Right-of-way ban
- No wall without County Board OK (40-5-5(C))
- Setback trigger
- Over 6 ft, yard setbacks apply (40-5-5(D))
- Building permit exempt
- Walls under 4 ft (Sec. 7-1-28(A)(4))
- Zoning certificate
- Still required at any height (Sec. 40-11-2)
- Penalty
- Class B misdemeanor, $50-$500 plus costs/day
Summary
Zoning Ordinance Sec. 40-5-5(C) bars building a retaining wall inside any public street or alley right-of-way in unincorporated St. Clair County unless the County Board specifically authorizes it. A wall on a public easement or across a ditch must not block drainage, and the owner pays to remove or replace it if the county ever needs the right-of-way back.
40-5-5 FENCES, WALLS, AND HEDGES. Fences, walls, or hedges used for any purpose shall in all districts conform to the following: (C) No permanent fence or retaining wall shall be constructed or erected within any public street or alley right-of-way unless specifically authorized by the County Board. Fences erected on public easement or across ditches shall be so constructed that drainage shall not be obstructed and, in event of necessity for removal of such fence for maintenance or other purpose, removal and/or replacement of such fence or other improvement shall be the responsibility of the property owner at the owner's expense. (D) Fences, walls, and hedges in any district may be located along lot lines, provided such fences, walls and hedges exceeding six (6) feet high shall be subject to the minimum yard requirements of the district in which such fences are located. 40-11-10 PENALTIES. (A) Any person who is convicted of a violation of this Code shall be guilty of a Class B misdemeanor and shall be fined not less than Fifty Dollars ($50.00) nor more than Five Hundred Dollars ($500.00), plus costs. Each day that a violation continues shall be considered a separate offense.
Full Breakdown
Sec. " A wall placed on a public easement or across a drainage ditch must still let water flow, and if the county later needs to remove the wall for maintenance or any other purpose, the property owner bears the cost of taking it out and putting it back, at the owner's own expense, not the county's. Subsection (D) adds a height trigger that reaches taller retaining walls used along a lot line: once a wall, grouped with fences and hedges in the same sentence, exceeds six feet, it becomes "subject to the minimum yard requirements of the district in which such fences are located," meaning a tall wall must sit back from the lot line the same distance a principal structure would, not sit directly on it.
The building code separately exempts retaining walls under 4 feet, measured from the footing to the top of the wall, from a building permit (Sec. 7-1-28(A)(4)) unless the wall supports a surcharge or impounds Class I, II or III-A liquids, but that exemption is only from the building permit: a Certificate of Zoning Compliance under Sec. 40-11-2 is still required before any new structure, including a retaining wall of any height, is erected.
Violations & Fines
Building a retaining wall in a right-of-way without County Board authorization, or building one that violates the six-foot yard-setback trigger, is a Zoning Code violation. Sec. 40-11-10 makes any violation a Class B misdemeanor, fined not less than $50 nor more than $500 plus costs, with each day the violation continues counted as a separate offense, and the Zoning Administrator can also issue a corrective action order under Sec. 40-11-5 ordering the wall removed or altered by a set deadline.
Frequently Asked Questions
Can I build a retaining wall in the road right-of-way or on a drainage easement?
Does a low retaining wall still need a permit?
Do tall retaining walls have to be set back from the property line?
Sources & Official References
Other rules in St. Clair County
Compare St. Clair County to another location·View the Illinois fence regulations overview
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