Chapel Hill, NC Hurricane Preparedness: Flood Elevation (2026)

Section 5-54 defines "base flood elevation" as the water surface elevation of the flood with a one percent annual chance, drawn from the flood insurance study or, where none exists for a special flood hazard area, from FEMA-approved engineering studies, and defines "freeboard" as the added height covering unknown factors like wave action, bridge openings and urbanization's effect on runoff. Combined, the base flood elevation plus two feet of freeboard becomes the "regulatory flood protection elevation" wherever base flood elevations have been determined. Section 5-60(1) requires new construction and substantial improvement of any residential structure, including manufactured homes, to have its reference level, including any basement, elevated no lower than that regulatory flood protection elevation.

Section 5-60(2) allows nonresidential structures to meet the same elevation or be floodproofed to it instead, with a professional engineer's or architect's certification and an operation and maintenance plan on file. Section 5-63(3) covers watercourses with no base flood elevation data: the reference level must still be elevated at least two feet above the highest adjacent grade. Section 5-66 requires that elevation to be documented on a certificate submitted to the floodplain administrator, and Section 5-54 presumes a structure is in violation until that documentation is actually provided.