Island County, WA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Residential freeboard
- 1 foot above base flood elevation, A zone
- Nonresidential freeboard
- 1 foot above BFE or ASCE 24, higher wins
- No BFE data
- Lowest floor 2 feet above highest adjacent grade
- V zone
- Lowest structural member 1 foot above base flood level
- Elevation certificates
- 3 required during construction, licensed surveyor
- Variance body
- Hearing Examiner, Type III process
Summary
Island County requires new and substantially improved buildings in a mapped A zone to elevate the lowest floor at least one foot above the base flood elevation, and coastal V-zone structures at least one foot above base flood level on pilings, under Island County Code Section 14.02A.050. Nonresidential buildings may instead meet the ASCE 24 standard if it produces a higher elevation.
a.In all A zones where the base flood elevation has been determined or can be reasonably obtained, new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated one foot or more above the base flood elevation. ... a.In A zones where the base flood elevation has been determined or can reasonably be obtained, new construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall have the lowest floor, including basement, elevated one foot or more above the base flood elevation, or elevated as required by ASCE (American Society of Civil Engineers) 24, whichever is greater;
Full Breakdown
050 sets Island County's flood-hazard-reduction standards for the unincorporated county. Where base flood elevation data exists for an A zone, new construction and substantial improvement of a residential structure must have its lowest floor, including any basement, elevated one foot or more above the base flood elevation; nonresidential buildings in an A zone must meet the same one-foot freeboard or the elevation required by ASCE 24, whichever is higher. If base flood elevation data is unavailable for an A-zone lot, the lowest floor must sit at least two feet above the highest adjacent grade.
Crawlspaces are allowed only if the interior grade is no more than two feet below the lowest adjacent exterior grade, the crawlspace foundation wall does not exceed four feet, and floodwater velocity at the site stays under five feet per second. 070 requires the bottom of the lowest horizontal structural member to sit one foot or more above the base flood level on pilings or columns, anchored against wind and water loads calculated on a hundred-year recurrence interval, with the space below built to break away rather than obstruct floodwaters.
Elevation certificates from a Washington-licensed surveyor are required three times during construction, and a professional engineer or architect must certify any dry flood-proofing used as an alternative for nonresidential buildings.
Violations & Fines
Failing to meet the freeboard elevation before the Floodplain Administrator signs off on a certificate of occupancy leaves a structure in violation of Chapter 14.02A, enforced through the code-enforcement process at Sections 17.03.260.B and 17.03.260.D through .G. A variance from the Hearing Examiner is granted only for a unique hardship on a half-acre lot or smaller, and issuance still raises flood-insurance costs, up to twenty-five dollars per hundred dollars of coverage.
Frequently Asked Questions
How high above flood level must I build in Island County?
What if my Island County lot has no base flood elevation data?
Are crawlspaces allowed below the base flood elevation in Island County?
Sources & Official References
Other rules in Island County
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