Cowlitz County, WA Environmental Rules: Flood Elevation Requirements (2026)

080(B)(1)(a) requires new construction and substantial improvement of any residential structure in an AE, A1-30, or other A-zoned area to have its lowest floor, including any basement, and all machinery, utilities and mechanical equipment elevated one foot or more above the BFE. 080(B)(2)(a)(i) sets the freeboard at two feet or more above the BFE, or to the higher standard required by ASCE 24, whichever is greater, with mechanical equipment and utilities waterproofed or elevated to the same two-foot standard. 080(B)(1)(b) and (D) require at least two feet of freeboard above the mapped depth number, or two feet above the highest adjacent grade if no depth number is shown.

080(B)(1)(c) requires the lowest floor to sit at least two feet above the highest adjacent grade. Enclosed areas below the elevated lowest floor are prohibited unless they meet flood-vent standards: a minimum of two openings totaling at least one square inch per square foot of enclosed area, with the lowest opening no higher than one foot above grade. 080(B)(3).