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

Section 1386.28(d) is the residential elevation rule. 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, including basement, must be elevated at least two feet above the highest adjacent natural grade. Support structures and other foundation members must be certified by a registered professional engineer or architect as designed in accordance with ASCE, Flood Resistant Design Construction.

The definitions in Section 1386.11 give the freeboard figure. The base flood is the flood having a one percent chance of being equaled or exceeded in any given year. The flood protection elevation (FPE) is the base flood elevation plus two feet of freeboard. Where no base flood elevations exist from any authoritative source, the FPE can be historical flood elevations, or base flood elevations determined and approved by the floodplain administrator. In Zone AO, the base flood elevation is the natural grade elevation plus the depth number, from one to three feet. Substantial improvement means work whose cost equals or exceeds fifty percent of the market value of the structure before the start of construction of the improvement.

Enclosures below the lowest floor are limited. Under Section 1386.28(e), a structure elevated to the FPE on pilings, columns, posts or solid perimeter walls with openings can have an enclosure used only for parking of vehicles, building access, or storage, with either engineer or architect certification of automatic equalization of flood forces or a minimum of two openings on different walls totaling not less than one square inch of net area for every square foot of enclosed area, with the bottom of each opening no higher than one foot above grade. Nonresidential structures must be elevated to the FPE or be dry floodproofed to it with a FEMA Floodproofing Certificate (Section 1386.29). Street surfaces in a subdivision must sit at or above the base flood elevation (Section 1386.27(i)).