15.55.270 Residential structures.
A. New construction and substantial improvement of any residential structure within a SFHA shall have the lowest floor, including basement, elevated to or above the higher of either:
1. The base flood elevation plus two (2) feet, or
2. An elevation one and one-half (1.5) feet above the average centerline of the adjacent street, or as determined by the city engineer if special topography conditions warrant.
B. New construction of any residential structure within a Zone X shall have the lowest floor, including basement, elevated to or above an elevation one and one-half (1.5) feet above the average centerline of the adjacent street, or as determined by the city engineer if special topography conditions warrant. A FEMA Elevation Certificate is not required for new construction within a Zone X.
C. The structure shall be aligned parallel with the direction of flood flows where practicable.
D. The structure shall be anchored to prevent flotation, collapse, or lateral movement of the structure.
E. All materials below the base flood elevation plus two (2) feet shall be resistant to flood damage and firmly anchored to prevent flotation. Materials harmful to aquatic wildlife, such as creosote, are prohibited below the base flood elevation plus two (2) feet.
F. Electrical, heating, ventilation, duct work, plumbing, and air conditioning equipment and other service facilities shall be elevated above the base flood elevation plus two (2) feet. Water, sewage, electrical, and other utility lines below the base flood elevation plus two (2) feet shall be constructed so as to prevent water from entering or accumulating within them during conditions of flooding.
G. Fully enclosed areas below the lowest floor that are subject to flooding shall be used only for parking, storage, or building access and shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement shall either be certified by a registered professional engineer or licensed architect or meet or exceed the following minimum criteria:
1. A minimum of two (2) openings having a total net area of not less than one (1) square inch for every square foot of enclosed area subject to flooding shall be provided.
2. The bottom of all openings shall be no higher than one (1) foot above grade.
3. Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.
4. The bottom of the crawlspace or enclosed area shall be either:
a. At or above the lowest adjacent exterior grade; or
b. Less than two (2) feet below the lowest adjacent exterior grade and the height of the enclosed area, measured from the interior grade of the crawlspace to the top of the crawlspace foundation wall, does not exceed four (4) feet at any point.
H. Upon completion of the construction and before issuance of the certificate of occupancy, the permit applicant shall provide a current “finished construction” FEMA Elevation Certificate (FEMA form 81-31), signed and sealed by a professional land surveyor, currently licensed in the state of Washington.
I. Upon completion of the construction of an elevated building and before issuance of the certificate of occupancy, the applicant shall provide a signed nonconversion agreement that acknowledges that the conversion of the area below the lowest floor to a use or dimension contrary to the building’s originally approved design is prohibited.
1. The nonconversion agreement shall authorize the floodplain administrator to conduct inspections of the enclosed area of the building upon reasonable notice.
2. The applicant shall record the nonconversion agreement with the County Auditor.
3. A copy of the recorded nonconversion agreement shall be presented as a condition of issuance of the final certificate of occupancy.
4. The floodplain administrator may waive this requirement where the enclosed area is less than four (4) feet in height, measured from the floor of the enclosure to the underside of the floor system above.