Rohnert Park, CA Environmental Rules: Flood Elevation Requirements (2026)

170 sets the construction standards that apply throughout the city's areas of special flood hazard. For residential construction, all new buildings and substantial improvements must have their lowest floor, including any basement, elevated at least one foot above the base flood elevation in Zone AE, AH or A1-30. In an AO zone, the lowest floor must sit above the highest adjacent grade at a height at least one foot above the depth number shown on the FIRM, or at least two feet above the highest adjacent grade if no depth number is specified.

140(C). Once construction is complete, a registered civil engineer or licensed land surveyor must certify the lowest floor elevation, and the community building inspector must verify that the structure was properly elevated; that certification and verification go to the floodplain administrator and are kept on file for public inspection. Nonresidential structures may instead be dry-floodproofed below that same elevation if a registered civil engineer or architect certifies the structure is watertight and can resist hydrostatic and hydrodynamic loads. New construction must also be built with flood-resistant materials below the base flood elevation, and enclosed areas below the lowest floor used only for parking, access or storage must include flood openings sized at not less than one square inch of net open area per square foot of enclosed area subject to flooding, with the bottom of openings no higher than one foot above grade.