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

110, "Construction Standards," governs every area of special flood hazard mapped on the Flood Insurance Rate Map under the city's floodplain management chapter (Ordinance 2837, amended by Ordinance 2992 in 2025). Subsection C, "Elevation and Floodproofing," sets the freeboard requirement: residential construction, whether new or a substantial improvement, in Zone AE, AH, or A1-30 must have its lowest floor, including any basement, elevated two feet above the base flood elevation, with the finished elevation certified by a registered professional engineer or surveyor, or verified by the chief building official.

In Zone AO, the lowest floor must be elevated above the highest adjacent grade to a height exceeding the FIRM-specified depth number by at least two feet, or at least four feet above grade if no depth number is specified. In Zone A, where no BFE has been established, the lowest floor must still be elevated at least two feet above the base flood elevation once one is determined. Nonresidential construction in AO zones may instead be floodproofed to two feet above BFE with watertight, substantially impermeable walls certified by a registered engineer or architect.

Subsection A additionally requires anchoring against flotation and lateral movement, and utility equipment such as HVAC and electrical systems must be elevated at least one foot above BFE. Enclosed areas below the lowest floor used only for parking, access, or storage must include flood vents meeting a minimum of one square inch of net opening per square foot of enclosed area, with openings no higher than one foot above grade. 100.