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

140 sets the actual construction standards under Merced's floodplain chapter. For Zones AE and AH, the elevation rule is a hard floor: the lowest floor of a new or substantially improved structure, including any basement, must sit at or above the base flood elevation shown on the FEMA flood insurance rate map, and a registered professional engineer or surveyor, or the city's building inspector, must certify the as-built elevation to the city engineer before the project is considered compliant. In Zone AO, where FEMA maps a depth number instead of a BFE, the standard shifts to elevating the lowest floor above the highest adjacent natural grade by whatever depth is shown on the map, or at least two feet if no depth number is listed.

3: instead of elevating, they may be dry-floodproofed watertight below the flood level with walls and structural components capable of resisting hydrostatic and hydrodynamic loads, certified by a registered engineer or architect. 4, meaning at least two openings totaling one square inch of net area for every square foot of enclosed space, with the bottom of every opening no higher than one foot above grade. 5. 040, separately defines 'freeboard' as a safety margin above the calculated flood level that compensates for unknowns like wave action, but Merced's construction standard itself sets the floor at the base flood elevation rather than layering an additional freeboard requirement on top of it.