Corona, CA Environmental Rules: Flood Elevation Requirements (2026)

022 defines BFE as the base flood elevation shown on the Flood Insurance Rate Map for Zones AE, AH, A1-30, VE and V1-V30, representing the water surface elevation of a flood with a 1% or greater annual chance of occurrence. 010(C)(1) sets the elevation standard: new construction and substantial improvement of any residential structure must have the lowest floor, including basement, elevated to or above the BFE, with the finished elevation certified to the Floodplain Administrator by a registered engineer or surveyor, or verified by the Building Inspector.

010(C)(2) instead requires the lowest floor elevated above the highest adjacent grade by the depth number printed on the FIRM, or at least two feet if none is shown. 010(C)(3), be dry floodproofed watertight below the base flood level, with structural components able to resist hydrostatic and hydrodynamic loads, certified by a registered engineer or architect. 010(C)(4), have at least two openings totaling one square inch of net area per square foot of enclosed area, with opening bottoms no higher than one foot above grade, so floodwaters can enter and exit automatically.

The code does not add a freeboard margin above the mapped BFE for the standard residential case; the requirement is the FIRM elevation itself, or the AH/AO/VO alternative described above.