St. Peters, MO Fence Regulations: Retaining Walls (2026)

Section 405.360, Fence Requirements, sets the City's general fence standards and then adds district-specific rules. Subsection E covers "C" (Commercial) and "I" (Industrial) Districts and lets the Administrative Officer approve fences taller than six feet for security or screening, including barbed or razor wire with its lowest strand at least seven feet above grade. Item 9 of that subsection is narrower: any retaining wall over four feet high in a commercial district, or in a commercial development sited within an industrial district, must have a fence or rail on top of it, and that fence or rail must be at least thirty-six inches tall.

The rule sits alongside the chapter's other commercial fence provisions, including the requirement that fences abutting residential property be masonry, wood composite, or vinyl, and that outdoor restaurant and tavern seating areas be enclosed by a fence at least thirty-six inches high. Because the retaining-wall rail is installed in an "R-3," "C," or "I" district, it also falls under Section 405.360(F)(1)'s fence-permit rule, requiring a building permit, capped at fifty dollars, before construction. The City's Planning, Community and Economic Development Department, through its Neighborhood Preservation and code enforcement staff, administers both the fence permit and inspections of retaining wall sites in the City of St.

Peters, Missouri. Property owners in R-1 through R-4 residential districts are not subject to this specific rail mandate, since Subsection D governs residential fences separately and does not repeat the retaining-wall trigger.