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

Base flood elevation (BFE) is defined in § 8.55.050 as the water-surface elevation shown on the FIRM for Zones AE, AH, A1-30, VE, and V1-V30 for a flood with a one-percent annual chance of being equaled or exceeded, the 'one-hundred-year flood.' Section 8.55.160(C)(1) applies that figure to residential construction: in an unnumbered A zone with no BFE printed on the FIRM, the elevation must still be determined and met, using the base flood elevation data the floodplain administrator develops under § 8.55.140(C). Where the FIRM shows only a flood depth number rather than a BFE, the lowest floor must be raised above the highest adjacent grade by that depth number, or by at least two feet if no depth number is given.

Once the structure is finished, a registered civil engineer or licensed land surveyor must certify the as-built elevation of the lowest floor, and the community building inspector verifies it before that certification goes to the floodplain administrator (§ 8.55.160(C)(1)). Nonresidential buildings may substitute certified dry floodproofing to the same elevation instead of raising the floor (§ 8.55.160(C)(2)). Detached garages and small accessory structures may have a floor below the BFE only if they are limited to parking or storage, built of flood-resistant materials below the BFE, anchored, and designed to let floodwater automatically enter and exit (§ 8.55.160(C)(5)).