Merced County, CA Environmental Rules: Flood Elevation Requirements (2026)

050(A)(3)(a) sets the freeboard standard for residential construction in the county's mapped flood hazard areas. In an AO zone, the lowest floor, including any basement, must be elevated above the highest adjacent grade to a height one foot higher than the depth number shown on the Flood Insurance Rate Map, or at least two feet above the highest adjacent grade if no depth number is listed. 040(C)(2). In all other flood zones, the lowest floor must sit at or above the base flood elevation itself.

Once construction is finished, a registered professional engineer or surveyor must certify the elevation, and the County Building Inspector verifies the structure was properly elevated. 050(A)(3)(b), but the structure must be watertight below the freeboard elevation and certified by a registered engineer or architect. 050(D)(1), and must be secured to an anchored foundation system to resist collapse and lateral movement. 040(F) requires a FEMA Elevation Certificate to be handed to the floodplain administrator twice: once at the foundation-forms inspection, before concrete is poured, and again once construction is complete, before the county will issue a Certificate of Occupancy.