Newport Beach, CA Environmental Rules: Flood Elevation Requirements (2026)

200 sets the elevation and floodproofing standards that apply to all new construction and substantial improvements in areas of special flood hazard, including residential, nonresidential, and manufactured home structures. Residential construction must have its lowest floor, including any basement, elevated above the highest adjacent grade to a height equal to or exceeding the FIRM-specified depth number plus one foot of freeboard in an AO Zone, or at least two feet above the highest grade if no depth number is shown. 070. 050 defines the design flood elevation as the higher of the base flood elevation (the one percent annual chance flood) plus one foot of freeboard, or the elevation shown on an adopted flood hazard map.

Enclosed areas below the lowest floor used only for parking, building access, or storage must have flood vents: at least two openings on different walls providing one square inch of net area per square foot of enclosed area, with opening bottoms no higher than one foot above the higher of the interior or exterior finished grade. Nonresidential structures may instead be floodproofed watertight below the required elevation, with certification by a registered professional engineer or architect submitted to the Floodplain Administrator. Manufactured homes must be elevated to or above the base flood elevation and anchored to resist flotation, collapse, and lateral movement.

Upon completion, a registered professional engineer or surveyor must certify the as-built lowest floor elevation, which the City building inspector verifies before sign-off. Applicants must submit surveyor- or engineer-determined elevation data, floodproofing elevations relative to NAVD, and drainage and wall plans with the building permit application filed under the Newport Beach Administrative Code. Encroachments, including fill and new construction, are prohibited within designated floodways unless a registered civil engineer certifies through hydrologic and hydraulic analysis that the base flood discharge level will not rise.