Sonoma County, CA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard
- 12 inches above base flood elevation
- Trigger
- New construction or substantial improvement
- Permit
- Required before construction begins
- Administered by
- Chief Building Official / PRMD
- Scope
- Unincorporated county only
Summary
In unincorporated Sonoma County, new homes and substantial remodels inside a mapped special flood hazard area must raise the lowest floor at least 12 inches above the base flood elevation: a local freeboard buffer stacked on top of FEMA's bare minimum.
Residential Construction. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated above the base flood elevation at least twelve inches (12″).
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 64 Update 2).
Full Breakdown
Chapter 7B, adopted under the FEMA Flood Insurance Study and Flood Insurance Rate Maps for the county, requires a floodplain permit before any construction in a special flood hazard area (§ 7B-5). New construction and substantial improvement of a residential structure must elevate the lowest floor, including any basement, at least 12 inches above the base flood elevation (§ 7B-11(a)); nonresidential structures may instead be floodproofed to that same height. The chief building official, through Permit and Resource Management, administers the program and can grant limited variances (§§ 7B-6, 7B-8, 7B-9). This governs only unincorporated county land. Santa Rosa, Petaluma, Rohnert Park, Windsor, Healdsburg, Sebastopol, Cotati, Cloverdale and the City of Sonoma each administer their own floodplain chapters.
Violations & Fines
A structure is presumed noncompliant until an elevation certificate and other proof of compliance is filed with the county (§ 7B-1); building without the required floodplain permit blocks final inspection/occupancy, and building below the required elevation drives up federal flood insurance premiums.
Frequently Asked Questions
Does this cover the City of Sonoma?
What counts as a substantial improvement?
Sources & Official References
Other rules in Sonoma County
California rules heatmap·Compare Sonoma County to another location·View the California environmental rules overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.