O'Fallon, MO Fence Regulations: Height Limits (2026)

273(C) sets the citywide maximum fence height at six feet, six inches for fencing, accompanying structures and decorative posts, unless another part of the Section says otherwise. Fences may sit on any side or rear property line, but installing one forward of the required lot setback line is prohibited outright, except where more than one side of a lot fronts a public street; there, the fence may project up to ten feet past the building line on the street-facing side yard only, while the true front yard setback stays off-limits.

Every fence must also clear the City's twenty-five-foot sight triangle at corners and driveways so it does not impede a driver's view, and each fence needs a minimum three-foot gate or opening on any side that faces a street. Decorative posts under thirty inches can go in the front yard if kept at least two feet from the property line. Two paths exist to build taller than six feet, six inches: a conditional use permit under Chapter 400, Article VII, with the taller fence screened on its outward side with plants so it does not further block intersection sightlines, or no permit at all if a taller fence is needed to comply with some other City ordinance.