Wyandotte County, KS Environmental Rules: Flood Elevation Requirements (2026)

Section 27-552(b)(1) sets the county's freeboard standard: in numbered and unnumbered A, AE, and AH zones where base flood elevation (BFE) data exists, new construction, substantial improvement, or substantial damage repair of a residential structure, including a manufactured home, must have its lowest floor, including any basement, elevated a minimum of 18 inches above BFE, with that elevation certified by a licensed land surveyor or professional engineer. Non-residential structures face the identical 18-inch floor requirement, or may instead be dry floodproofed to 18 inches above BFE with certification from a registered engineer or architect.

All mechanical, electrical, plumbing, and HVAC equipment must likewise sit at least 18 inches above BFE. The rule treats an improvement or repair as 'substantial' once its cost, cumulated over a calendar year, exceeds 50 percent of the structure's market value, at which point the freeboof standard is triggered even for an existing building. Fill used to reach the required elevation must sit above the BFE and meet the adopted building code, and cannot worsen drainage onto neighboring land. AO zone structures instead must clear the highest adjacent grade by the flood depth number on the FIRM, or two feet if none is shown.