15.32.130: SPECIFIC PROVISIONS FOR FLOOD HAZARD REDUCTION IN RESIDENTIAL CONSTRUCTION:
Where base flood elevation data are available, new construction or substantial improvement of any residential structure or manufactured home must have the lowest floor, including basement, constructed at or above the flood protection elevation. All new construction or substantial improvements of an existing residential structure that includes a fully enclosed area located below the lowest floor formed by the foundation and other exterior walls must be designed to be an unfinished or flood resistant enclosure. The enclosure must be designed to equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwater. Designs for complying with this requirement must be certified by a licensed professional engineer or architect or meet the following minimum criteria:
   A.   Provide a minimum of two (2) openings meeting the following criteria:
      1.   A total net area of not less than one square inch for every square foot of enclosed area subject to flooding;
      2.   The bottom of all openings can be no higher than one foot (1') above the higher of the exterior or interior grade or floor immediately below the opening;
      3.   Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwater in both directions without manual intervention.
   B.   To comply with the "lowest floor" criteria of this chapter, the unfinished or flood resistant enclosure can only be used for parking of vehicles, limited storage of maintenance equipment used in connection with the premises, or entry to the elevated area.
   C.   The interior portion of such enclosed area cannot be partitioned or finished into separate rooms.
   D.   For crawl space foundation types, construction must follow FEMA guidelines, specifically:
      1.   Below grade crawl spaces are prohibited at sites where the velocity of floodwaters exceed five feet (5') per second;
      2.   Interior grade of the crawl space below the BFE cannot be more than two feet (2') below the lowest adjacent exterior grade (LAG);
      3.   Height of the below grade crawl space, measured from the lowest interior grade of the crawl space to the bottom of the floor joist must not exceed four feet (4') at any point;
      4.   Contain an adequate drainage system that removes floodwaters from the interior area of the crawl space. (Ord. 3380 §7, 2010)