In all areas of special flood hazard, the following standards shall be met.
(A) Anchoring.
(1) All 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.
(2) All manufactured homes shall meet the anchoring standards of § 18.20.040.
(B) Construction materials and methods.
(1) All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
(2) All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
(3) All 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 located so as to prevent water from entering or accumulating within the components during conditions of flooding.
(4) All new construction and substantial improvements within Zones AH, AO or VO shall be provided with adequate drainage paths to guide flood waters around and away from all structures.
(5) The use of breakaway walls must be certified by a registered engineer or architect and shall meet the following requirements:
(a) Breakaway wall collapse shall result from a water load less than that which would occur during the base flood;
(b) The elevated portion of the building shall not incur any structural damage due to the effects of wind and water loads active simultaneously in the event of the base flood; and
(c) The breakaway wall shall have a safe design loading resistance of not less than ten and no more than 20 pounds per square foot.
(C) Elevation and floodproofing.
(1) New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to or above the BFE. Upon the completion of the structure, the elevation of the lowest floor, including basement, shall be certified by a registered professional engineer or surveyor or verified by the Building Inspector to be properly elevated. The certification or verification shall be provided to the Floodplain Administrator. For special uses excluding any human occupancy, see subsection (C)(4) below.
(2) New construction and substantial improvement of any residential structure in Zone AH, AO or VO shall have the lowest floor, including basement, elevated above the highest adjacent grade at least as high as the depth number specified in feet on the Flood Insurance Rate Map, or at least two feet if no depth number is specified. Upon the completion of the structure, the elevation of the lowest floor, including basement, shall be certified by a registered professional engineer or surveyor, or verified by the Building Inspector to be properly elevated. Such certification or verification shall be provided to the Floodplain Administrator.
(3) Nonresidential construction shall either be elevated in conformance with § 18.20.010(C)(1) or (2) or, together with attendant utility and sanitary facilities, shall:
(a) Be floodproofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water; and
(b) Have structural components capable of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy; and
(c) Be certified by a registered professional engineer or architect as meeting the standards of subsections (a) and (b) above. Such certification shall be provided to the Floodplain Administrator.
(4) For all new construction and substantial improvements, any fully-enclosed area below the lowest floor that are useable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding 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 be certified by a registered professional engineer or architect and shall 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. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers, valves or other coverings or devices, provided that they permit the automatic entry and exit of floodwaters; or
(b) Compliance with a local floodproofing standard approved by the Federal Insurance Administration.
(5) Manufactured homes shall also meet the standards of this section.
(D) Garages and low cost accessory structures.
(1) Attached garages.
(a) A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry of flood waters. Areas of the garage below the BFE must be constructed with flood resistant materials.
(b) A garage attached to a nonresidential structure must meet the above requirements or be dry floodproofed. For guidance on below grade parking areas, see FEMA Technical Bulletin TB-6.
(2) Detached garages and accessory structures.
(a) "Accessory structures" used solely for parking (two-car detached garages or smaller) or limited storage (small, low-cost sheds) may be constructed such that its floor is below the BFE, provided the structure is designed and constructed in accordance with the following requirements:
(i) Use of the accessory structure must be limited to parking or limited storage;
(ii) The portions of the accessory structure located below the BFE must be built using flood-resistant materials;
(iii) The accessory structure must be adequately anchored to prevent flotation, collapse and lateral movement;
(iv) Any mechanical and utility equipment in the accessory structure must be elevated or floodproofed to or above the BFE;
(v) The accessory structure must comply with floodplain encroachment provisions in § 18.20.050; and
(vi) The accessory structure must be designed to allow for the automatic entry of floodwaters in accordance with § 18.20.010(C).
(b) Detached garages and accessory structures not meeting the above standards must be constructed in accordance with all applicable standards in this section.
(`78 Code, § 18.20.010.) (Ord. 2961 § 7, 2008; Ord. 2290 § 4, 1996; Ord. 1886 § 1 (part), 1988.)