Overland Park, KS Environmental Rules: Flood Elevation Requirements (2026)

Overland Park's floodplain chapter goes beyond FEMA's bare minimum by building in a mandatory freeboard margin. B applies in all numbered and unnumbered A zones, AE, and AH zones where Base Flood Elevation data exists. For residential construction, including manufactured homes, the lowest floor (including any basement) must be elevated a minimum of two feet above Base Flood Elevation, and mechanical and HVAC equipment must be raised or floodproofed to that same level. New residential construction also needs its lowest adjacent grade at least one foot above the energy grade line of the base flood under fully developed upstream conditions.

Non-residential structures get an alternative compliance path: elevate the lowest floor two feet above Base Flood Elevation, or floodproof the structure to that same two-foot mark so it is watertight, with walls substantially impermeable to water and structural components able to resist hydrostatic and hydrodynamic loads and buoyancy effects. A registered professional engineer or architect must certify the floodproofing standard is met. 7-9. 410) explains the purpose: a safety factor expressed in feet above a required water surface elevation, compensating for unknown factors like wave action, bridge openings, and hydrological uncertainty that could increase flood height beyond the calculated base flood.