Cincinnati, OH Environmental Rules: Flood Elevation Requirements (2026)

CBC Chapter 1109 governs all special flood hazard areas within Cincinnati's jurisdiction, based on the Flood Insurance Study and Flood Insurance Rate Map for Hamilton County effective June 7, 2023. 1 defines Flood Protection Elevation (FPE) as the base flood elevation plus one foot of freeboard, or, where no base flood elevation exists from an authoritative source, a historical flood elevation or an elevation approved by the floodplain administrator. 4(D) sets the operative standard for residential structures: new construction and substantial improvement of any residential structure, including manufactured homes, must have the lowest floor, including basement, elevated to or above the flood protection elevation; in Zone AO areas with no elevations specified, the lowest floor must be elevated at least two feet above the highest adjacent natural grade.

4(C)). An enclosure below the lowest floor is allowed only for parking, building access, or storage, and must either be engineered to automatically equalize hydrostatic pressure or have at least two openings on different walls totaling one square inch of net area per square foot of enclosed area, with opening bottoms no higher than one foot above grade. 4, and no permit issues until Chapter 1109's requirements are met.