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

Irvine adopted a floodplain overlay, Zoning Ordinance Chapter 5-2, that incorporates FEMA's Flood Insurance Study and Flood Insurance Rate Maps by reference and requires a development permit before any construction begins in a mapped area of special flood hazard under Section 5-2-13. Section 5-2-24.C sets the elevation standard: new residential construction or a substantial improvement must have its lowest floor, including any basement, elevated at least one foot above the base flood elevation in an A Zone or in any other zone; in an AO Zone without a mapped depth number, the floor must instead sit at least two feet above the highest adjacent grade, or one foot above the depth number shown on the FIRM if one is specified. The same section requires flood-resistant construction materials below the base flood elevation and utility equipment located or designed to keep water out during flooding.

The Floodplain Administrator, the City's designated official under Section 5-2-14, reviews every development permit for compliance, obtains base flood data from FEMA or the state when a site lacks a published elevation, notifies neighboring jurisdictions before any watercourse alteration, and keeps the required elevation certifications on file for public inspection under Section 5-2-15. Once construction is complete, a registered engineer or surveyor must certify the finished lowest-floor elevation, and the City's Chief Building Official must verify it before the Floodplain Administrator will sign off. Property owners who cannot meet the standard may seek a variance from the Planning Commission, but Irvine's code warns that a variance must not cause fraud on or victimization of the public because a home built below the base flood elevation carries decades of added flood risk under Section 5-2-27.