Stanislaus County, CA Environmental Rules: Flood Elevation Requirements (2026)

903 defines 'Utility and Miscellaneous Group U' for flood-hazard purposes to include agricultural buildings, aircraft hangars accessory to a one- or two-family home, barns, carports, fences more than six feet high, grain silos accessory to a residential use, greenhouses, livestock shelters, private garages, retaining walls, sheds, stables, and towers, essentially the accessory buildings and structures that don't fit a specific occupancy classification elsewhere in the building code. Beyond the building code's fire and life-safety rules, the section layers on flood-specific standards for any of these structures sited in a flood hazard area: new construction and substantial improvements must be anchored to resist flotation, collapse, or lateral movement from flood loads, including buoyancy, under design-flood conditions.

Where the structure is fully enclosed by walls, its lowest floor, including any basement, must be elevated to or above the design flood elevation under ASCE 24, or the structure must be dry floodproofed to that standard instead. If it isn't dry floodproofed, any enclosed area below the design flood elevation is limited to parking, storage, or building access, flood openings must be installed per ASCE 24, flood-damage-resistant materials are required below that elevation, and mechanical, plumbing, and electrical systems must be located or installed per ASCE 24 as well. 902, applies a similar elevation-or-floodproofing standard specifically to detached garages and accessory storage buildings under 600 square feet.