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

Milpitas Municipal Code section XI-15-5.1(c) sets the City's elevation and floodproofing standards for construction in areas of special flood hazard. For new or substantially improved residential construction, including manufactured homes, the lowest floor (including any basement) must be elevated: in Zone AO, above the highest adjacent grade by at least one foot more than the FIRM's specified flood depth number, or at least three feet above the highest adjacent grade if no depth number is specified; in Zone A, at least one foot above the base flood elevation as determined by the developer's engineer and approved by the City Engineer; and in all other zones, at least one foot above the base flood elevation.

That one-foot minimum is Milpitas's local freeboard above the federal base flood elevation. A registered professional engineer or surveyor must certify the completed lowest-floor elevation to the Floodplain Administrator (section XI-15-5.1(c)(1)). Nonresidential buildings may instead be floodproofed below that same elevation so the structure is watertight, with structural components able to resist hydrostatic and hydrodynamic loads, certified by a registered engineer or architect (section XI-15-5.1(c)(2)). Enclosed areas below the lowest floor used only for parking, access or storage must have at least two openings totaling one square inch of net area per square foot of enclosed area, with opening bottoms no higher than one foot above grade, to automatically equalize floodwater pressure (section XI-15-5.1(c)(3)).

Manufactured homes must also meet the elevation and anchoring standards of section XI-15-5.4, and the City Council may grant a variance from these elevation standards only on the strict, multi-factor showing in section XI-15-6.3, which requires a determination that no increase in flood heights or extraordinary public expense will result.