San Leandro, CA Environmental Rules: Flood Elevation Requirements (2026)

Section 7-9-500(c) sets the elevation standard for the whole flood chapter. New residential construction and substantial improvements must have their lowest floor, including any basement, "elevated to or above the base flood elevation, as determined by this community" in an A Zone, and elevated to or above the base flood elevation in all other zones; in an AO Zone the lowest floor must clear the depth number printed on the Flood Insurance Rate Map, or at least two feet above the highest adjacent grade if no depth number is shown.

The code notes that "the State of California recommends" going further: at least one foot above the base flood elevation in an A Zone, and at least three feet above adjacent grade (or one foot above the mapped depth number) in an AO Zone, the extra margin known as freeboard, though the enforceable local minimum remains the unadorned base flood elevation. Once the structure is finished, a registered professional engineer or land surveyor must certify the as-built lowest-floor elevation to the Floodplain Administrator under Section 7-9-500(c)(1)(iv).

Nonresidential buildings get a choice: meet the same elevation standard, or floodproof below it so the structure is watertight with walls "substantially impermeable to the passage of water," certified by a registered engineer or architect under Section 7-9-500(c)(2). Fully enclosed areas below the lowest floor used only for parking, access, or storage must let floodwater automatically flow in and out through a minimum of two openings totaling at least one square inch of net area per square foot of enclosed space, per Section 7-9-500(c)(3). "