Sumter County, SC Environmental Rules: Flood Elevation Requirements (2026)

Section 18-72(2) sets the elevation standard for commercial, industrial, and other nonresidential structures, including manufactured homes used nonresidentially, once FEMA base flood elevation data exists for the site: the lowest floor must sit no lower than two feet above base flood elevation, basements are prohibited, and any solid foundation perimeter wall used to reach that height must include flood-vent openings under Section 18-72(5). Unlike residential buildings, nonresidential structures located in A-zones have a second compliance path: floodproofing to the same two-foot-above-base-flood-elevation level instead of physically elevating, provided every area below that line is watertight with walls substantially impermeable to water and structural components able to resist hydrostatic and hydrodynamic loads and buoyancy.

A registered professional engineer or architect must certify that the floodproofing standard is met, submitting that certification to the Floodplain Administrator under Section 18-54(a). Floodproofed structures also need an approved maintenance plan with an annual exercise, filed with and verified by the Floodplain Administrator. Section 18-71's general standards apply on top of this: all new construction and substantial improvements must be anchored against flotation and lateral movement, built with flood-resistant materials, and designed so utilities, water supply and sewage systems are protected from floodwater infiltration during a base-flood-plus-two-feet event.