Union City, CA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Elevation standard
- Lowest floor at/above base flood elevation
- Certification
- Registered engineer or surveyor required
- Manufactured homes
- Same to-or-above standard applies
- Freeboard
- No added margin specified in code
Summary
Union City requires new construction and substantial improvements in flood hazard areas to elevate the lowest floor to or above the base flood elevation, certified by a licensed engineer or surveyor.
New construction and substantial improvement of any structure shall have the lowest floor, including basement, elevated to or above the base flood elevation. Nonresidential structures may meet the standards in paragraph c of this subdivision. Upon the completion of the structure, the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, or verified by the Community Building Inspector to be properly elevated. Such certification or verification shall be provided to the Director.
b. New construction and substantial improvement of any structure in Zone AH or AO shall have the lowest floor, including basement, elevated above the highest adjacent grade at least as high as the depth number specified in feet on the FIRM, or at least two feet if no depth number is specified. Nonresidential structures may meet the standards in paragraph c of this subdivision. Upon the completion of the structure, the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, or verified by the Community Building Inspector to be properly elevated. Such certification or verification shall be provided to the Floodplain Administrator.
c. Nonresidential construction shall either be elevated in conformance with paragraphs a and b of this subdivision or together with attendant utility and sanitary facilities:
i.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4940544; v16 updated 2026-06-23).
Full Breakdown
In any FEMA-mapped special flood hazard area, Union City Municipal Code § 18.98.050(A)(3)(a) requires new construction and substantially improved structures to have their lowest floor, including any basement, elevated to or above the base flood elevation - the one-percent-annual-chance flood level shown on the city's Flood Insurance Rate Map. A registered professional engineer or surveyor must certify the finished elevation, or the Community Building Inspector must verify it, before the Economic and Community Development Director signs off. Manufactured homes must meet the same to-or-above standard under § 18.98.050(D). The code sets no additional freeboard margin beyond the base flood elevation itself.
Violations & Fines
A structure lacking an elevation certificate or other proof of compliance is presumed in violation under § 18.98.020, and building without complying with Chapter 18.98 is a misdemeanor under § 18.98.030(C).
Frequently Asked Questions
How high above flood level must I build in Union City?
Who certifies the elevation of a new structure?
Sources & Official References
Other rules in Union City
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Flood Elevation Requirements in Nearby Cities
How other cities in Alameda County handle flood elevation requirements.