(A) In all special flood hazard areas.
(1) New construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure.
(2) New construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
(3) New construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
(4) Electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities shall be designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
(B) Specific building design and construction standards for non-coastal residential construction (all A Zones) in addition to division (A).
(1) New construction and substantial improvement of residential structures located in non-coastal flood zones shall have the lowest floor, including basement, elevated a minimum of one foot above the base flood elevation or three feet above highest adjacent grade where no BFE is defined.
(2) New construction and substantial improvement that have fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement andare subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of flood waters. Designs for meeting this requirement must be either be certified by a registered professional engineer or architect and must meet or exceed the following minimum criteria:
(a) A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided;
(b) The bottom of all openings shall be no higher than one foot above grade, and;
(c) Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of flood waters.
(C) Specific building design and construction standards for non-coastal, non-residential construction. In addition to division (A), new construction and substantial improvement of any commercial, industrial, or other non-residential structure shall either have the lowest floor, including basement, elevated according to Table 2-1 the American Society of Civil Engineers, Flood Resistant Design and Construction Standard (ASCE 24); or, together with attendant utility and sanitary facilities, shall:
(1) Be flood-proofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water;
(2) Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
(3) Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this division based on their development and/or review of the structural design, specifications, and plans. Such certifications shall be provided to the Floodplain Administrator;
(4) Non-residential structures that are elevated, not flood-proofed, must meet residential standards described in § 153.54; and
(5) Applicants flood-proofing non-residential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the flood-proofed level (for example, a building flood-proofed to the base flood level will be rated as one foot below).
(D) Specific building design and construction standards for manufactured dwellings, non-coastal. In addition to divisions (A) and (B)(2), new, replacement, and substantially improved manufactured dwellings are subject to the following standards:
(1) If the manufactured dwelling is supported on solid foundation walls, the ground area reserved for the placement of a manufactured dwelling shall be a minimum of one foot above BFE unless the foundation walls are designed to automatically equalize hydrostatic forces by allowing for the entry and exit of flood waters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria:
(a) A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided;
(b) The bottom of all openings shall be no higher than one foot above grade, and;
(c) Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of flood waters.
(2) The bottom of the longitudinal chassis frame beam in A Zones, shall be at or above BFE (see Manufactured Dwelling Installation Specialty Code Interpretation dated January 1, 2011).
(3) The manufactured dwelling shall be anchored to prevent flotation, collapse, and lateral movement during the base flood. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors (see FEMA’s Manufactured Home Installation in Flood Hazard Areas Guidebook for additional techniques); and
(4) Electrical crossover connections shall be a minimum of 12 inches above BFE (see Manufactured Dwelling Installation Specialty Code 6-4.1(1)).
(E) Standards for shallow flooding areas (AO Zones). Shallow flooding areas appear on FIRMs as AO zones with depth designations that range from one to three feet above ground where a clearly defined channel does not exist, or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is often characterized as sheetflow. In these areas division (A) of this appendix and the following provisions shall apply.
(1) New construction and substantial improvements of residential structures and manufactured homes within AO Zones shall have the lowest floor (including basement) elevated above the highest grade adjacent to the building, a minimum of one foot above the depth number specified on the FIRM (at least three feet above HAG if no depth number is specified). See Oregon Residential Specialty Code R324.2.1, and 44 CFR Part 60.3(c)(7).
(2) New construction and substantial improvements of non-residential structures within AO Zones shall either:
(a) Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site, one foot or more above the depth number specified on the FIRM (at least three feet above HAG if no depth number is specified); or
(b) Together with attendant utility and sanitary facilities, be completely flood-proofed to or above that level so that any space below that level is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. If this method is used, compliance shall be certified by a registered professional engineer or architect.
(Ord. 527, passed 1-14-2013)