Mendocino County, CA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Standard freeboard
- 1 foot above base flood elevation
- AO zone floors
- Depth number + 1 ft, min. 3 ft
- Manufactured homes
- State recommends 2 ft above BFE
- Nonresidential option
- Dry-floodproof per ASCE 24
- Certification required
- By licensed engineer or surveyor
- Detached accessory limit
- 600 sq ft, flood openings required
Summary
New or substantially improved residential buildings in a Mendocino County flood hazard area must have their lowest floor at least one foot above the base flood elevation, certified by a licensed engineer or surveyor after construction.
Residential construction, new or substantial improvement, shall have the lowest floor, including basement: (i) In an AO zone, elevated to a height above the highest adjacent grade of not less than the depth number specified in feet (mm) on the FIRM plus one (1) foot (305mm), or not less than three (3) feet (915 mm) if a depth number is not specified. (ii) In all other Zones, elevated at least one (1) foot above the base flood elevation, as determined by the County.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 75).
Full Breakdown
Sec. ' Once built, the elevation of the lowest floor must be certified by a registered professional engineer or surveyor and verified by the community building inspector, with that certification filed with the Floodplain Administrator. Nonresidential structures in Zones A1-30, AE, and AH face a parallel standard under Sec. 405(B): elevate to or above base flood level per ASCE 24, or dry-floodproof the structure below that level with substantially impermeable walls capable of resisting hydrostatic and hydrodynamic loads. Manufactured homes carry a higher state-recommended margin: Sec.
' Detached garages and accessory structures under 600 square feet may sit below the base flood elevation only if anchored, built with flood-resistant materials, and fitted with flood openings under Sec. 405(B)(2).
Violations & Fines
Sec. 22.17.215 makes constructing or altering a structure without complying with these elevation standards a misdemeanor, enforceable by the Department of Planning and Building Services, which may take lawful action to prevent or remedy the violation. Under Sec. 22.17.405(C), any enclosed area below the required elevation used for parking, storage, or access must have flood openings totaling at least one square inch per square foot of enclosed area, with the lowest opening no higher than one foot above grade, or be certified by a registered engineer or architect; failing to meet either standard leaves the enclosure out of compliance and subject to the same misdemeanor enforcement.
Frequently Asked Questions
How high above the base flood elevation must a new house be built in Mendocino County?
Who certifies that a building meets the elevation requirement?
Do manufactured homes have a different flood elevation standard?
Sources & Official References
Other rules in Mendocino County
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