Contra Costa County, CA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard, Bay Delta Estuarine Region
- 2 feet (0.61 m) above BFE
- Freeboard, rest of county
- 1 foot (0.30 m) above BFE
- Certification required from
- Registered engineer/surveyor or building inspector
- Under-floor gap ≥ 6.6 ft
- Deed restriction required
- Governing section
- Ordinance Code § 82-28.1002(3)(a)
Summary
New construction and substantially improved buildings inside a Contra Costa County flood hazard area must sit above the base flood elevation plus a required safety margin, or freeboard, set at two feet in the San Francisco Bay Delta Estuarine Region and one foot everywhere else in the unincorporated county.
New construction and substantial improvement of any structure shall have the lowest floor, including basement, elevated to or above the base flood elevation plus required freeboard. In the San Francisco Bay Delta Estuarine Region, 0.61 meters (two feet) of freeboard is required. In all other unincorporated areas of the county, 0.30 meters (one-foot) of freeboard is required.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Ordinance Code: Supplement 103).
Full Breakdown
462 defines freeboard as a safety factor, expressed in feet above the base flood elevation, meant to cover unknown variables such as wave action and the hydrological effects of urbanizing a watershed. 406 defines base flood elevation (BFE) as the height above mean sea level to which the base, or one-hundred-year, flood is expected to rise, as determined by FEMA or the county's floodplain administrator. 30 meters (one foot) everywhere else in the unincorporated county. 1002(3)(b) instead measures from the highest adjacent grade, using the FIRM's depth number plus freeboard, or at least two feet if the map lists no depth number.
Before the building is finished, but after the substructure is complete, a registered engineer or surveyor must certify the elevation of the lowest floor, or the county building inspector must verify it, and that certification goes to the floodplain administrator. 6 feet) or more, the owner must record a deed restriction limiting that under-floor space to parking, storage, or access, never habitable space. 1012.
Violations & Fines
Framing a lowest floor below the base flood elevation plus the required one or two feet of freeboard, or skipping the substructure elevation certification the floodplain administrator must receive under Section 82-28.1002(3)(a), is a Section 82-28.606 violation, prosecuted as an infraction under Government Code Section 25132; the county can also withhold final building sign-off until the required elevation certificate is filed.
Frequently Asked Questions
How high above the base flood elevation must my house sit in Contra Costa County?
Who certifies that my new floor is elevated correctly?
What if the space under my elevated house is more than 6.6 feet tall?
Sources & Official References
Other rules in Contra Costa County
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