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

090. For elevation, residential new construction or substantial improvement must have its lowest floor, including any basement, elevated to one foot above the base flood elevation in an A Zone or any other zone; in an AO Zone, the floor must sit one foot above the FIRM's specified flood depth number, or at least two feet above the highest adjacent grade if no depth number is given. 070. Once construction is complete, a registered professional engineer or surveyor must certify the lowest floor elevation on a FEMA elevation certificate, verified by the city building inspector and filed with the Community Development Director.

Nonresidential structures may instead be floodproofed below the required elevation so the structure is watertight, with structural components able to resist hydrostatic and hydrodynamic loads, certified by a registered engineer or architect. Fully enclosed areas below the lowest floor used only for parking, access or storage must allow floodwater to enter and exit automatically, either through engineer-certified design, an approved local floodproofing standard, or a minimum of two openings totaling at least one square inch of net area per square foot of enclosed area, with opening bottoms no higher than one foot above grade.

Detached garages and small accessory structures (limited to parking two cars or storage sheds under 150 square feet and $1,500 in value) may have floors below the BFE if flood-resistant materials are used below the BFE and mechanical equipment is elevated or floodproofed to one foot above the BFE.