§ 158.054  RESIDENTIAL STRUCTURES.
   (A)   New construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. Where a structure, including its foundation members, is elevated on fill to or above the base flood elevation, these requirements for anchoring and construction materials resistant to flood damage in division (B) of this section are satisfied.
   (B)   New construction and substantial improvements shall be constructed with methods and materials resistant to flood damage.
   (C)   New construction and substantial improvements shall be constructed with electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities that are designed and/or elevated so as to prevent water from entering or accumulating within the components during conditions of flooding.
   (D)   New construction and substantial improvement of any residential structure, including manufactured homes, shall have the lowest floor, including basement, elevated to or above the flood protection elevation. (If Hillsboro is determined to have AO Zones: in Zone AO areas with no elevations specified, the structure shall have the lowest floor, including basement, elevated at least two feet above the highest adjacent natural grade.)
   (E)   New construction and substantial improvements, including manufactured homes, that do not have basements and that are elevated to the flood protection elevation using pilings, columns, posts, or solid foundation perimeter walls with openings sufficient to allow unimpeded movement of flood waters may have an enclosure below the lowest floor, provided the enclosure meets the following standards:
      (1)   Be used only for the parking of vehicles, building access, or storage; and
      (2)   Be designed and certified by a registered professional engineer or architect to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of flood waters; or
      (3)   Have a minimum of two openings on different walls having a total net area not less than one square inch for every square foot of enclosed area, and the bottom of all such openings being no higher than one foot above grade. The openings may be equipped with screens, louvers, or other coverings or devices, provided that they permit the automatic entry and exit of flood waters.
   (F)   Manufactured homes shall be affixed to a permanent foundation and anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors.
   (G)   Repair or rehabilitation of historic structures upon a determination that the proposed repair or rehabilitation will not preclude the structure’s continued designation as a historic structure and is the minimum necessary to preserve the historic character and design of the structure, shall be exempt from the development standards of this section.
   (H)   (If Hillsboro is determined to have AO Zones: in AO Zones, new construction and substantial improvement shall have adequate drainage paths around structures on slopes to guide flood waters around and away from the structure.)
(1982 Code, § 158.44)  (Ord. 2011-1, passed 2-14-2011)