Cathedral City, CA Environmental Rules: Flood Elevation Requirements (2026)

Section 8.24.050(A)(3) sets the elevation rule for every area of special flood hazard in Cathedral City. The base flood elevation (BFE) is the water surface elevation shown on the Flood Insurance Rate Map for zones AE, AH, A1-30, VE and V1-V30, from a flood with a one percent or greater chance of occurring in any given year. New residential construction and substantial improvements, meaning work costing fifty percent or more of the structure's market value, must put the lowest floor at or above that elevation in AE, AH and A1-30 zones. In an unnumbered A zone with no BFE on the FIRM, the floor still goes to or above the BFE, determined from other available data under § 8.24.040(B)(3). In an AO zone the floor must stand above the highest adjacent grade by at least the depth number printed on the FIRM, or at least two feet when no depth number is specified.

When the structure is finished, a registered civil engineer or licensed land surveyor certifies the lowest floor elevation, and the community building inspector verifies it. Both go to the floodplain administrator, who is the city engineer.

Nonresidential buildings either meet the same elevation or are floodproofed so the structure is watertight, with components that resist hydrostatic and hydrodynamic loads and buoyancy, certified by a registered civil engineer or architect. Fully enclosed areas below the lowest floor used only for parking, access or storage need flood openings: at least two openings on different sides, total net area not less than one square inch for every square foot of enclosed area, with the bottom of each opening no higher than one foot above grade. Residential structures cannot have subgrade enclosed areas at all, including below-grade garages and storage areas, because those count as basements.

Detached garages for no more than two cars, and sheds under one hundred fifty square feet and one thousand five hundred dollars in value, can have floors below the BFE if they are limited to parking or storage, anchored, built of flood-resistant materials, and fitted with flood openings. Manufactured homes in AE, AH and A1-30 zones go on permanent foundations with the lowest floor at or above the BFE.