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

Section 15.16.170 sets Rocklin's freeboard standard: in AE, AH and A1-30 flood zones, all new construction or substantial improvement of residential structures must have the lowest floor, including any basement, elevated to at least two feet above the base flood elevation. In an AO zone lacking a specified depth number, the same two-foot elevation above the highest adjacent grade applies, and in an unnumbered A zone without a mapped base flood elevation, the city engineer determines the required elevation under Section 15.16.140. Once the structure is complete, a registered civil engineer or licensed land surveyor must certify the elevation of the lowest floor, and the city's community building inspector must verify the structure was properly elevated before that certification is provided to the city engineer.

Nonresidential structures may instead be floodproofed to the same elevation if certified watertight by a registered civil engineer or architect, with structural components able to resist hydrostatic and hydrodynamic loads. New construction must also use flood-resistant materials below the base flood elevation and be adequately anchored against flotation, collapse or lateral movement, per Section 15.16.170.A and .B. Detached garages and small accessory structures may have their floor below the base flood elevation only if built with flood-resistant materials and designed to allow automatic entry of floodwater. This chapter was adopted by Ordinance No. 967 on January 25, 2011, implementing Government Code Sections 65302, 65560 and 65800.