In all special flood hazard areas, the following standards are required.
(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 § 153.49(B) of this chapter.
(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) Within Zones AH or AO, adequate drainage paths shall be constructed around structures on slopes to guide flood waters around and away from proposed structures.
(C) Elevation and flood-proofing.
(1) Residential construction.
(a) Residential construction, new or substantial improvement, shall have the lowest floor, including basement, elevated to or above the regulatory flood elevation.
1. In a Zone AO, the base flood elevation is determined from the FIRM panel. If unspecified, the required elevation is at minimum two feet above highest adjacent grade.
2. In a Zone A where the base flood elevation has not been determined, the base flood elevation is determined locally by the criteria set out in § 153.30(B)(3) of this chapter.
3. In Zones AE and AH, the base flood elevation is determined from the FIS and/or FIRM.
4. A garage attached to a residential structure, constructed with the garage floor slab below the regulatory flood elevation, must be designed to allow for the automatic entry and exit of flood waters. See divisions (C)(5)(a) or (C)(5)(b) below.
(b) Upon completion of the structure, certification by a registered professional engineer or surveyor that the elevation requirements of the lowest floor, including basement, of this section have been satisfied shall be provided to the Floodplain Administrator for verification.
(2) Non-residential construction.
(a) Non-residential construction, new or substantial improvement, shall have the lowest floor either elevated to conform with division divisions (C)(1)(a)1., (C)(1)(a)2. or (C)(1)(a)3. above, as appropriate, or together with attendant utility and sanitary facilities:
1. Be flood-proofed below the elevation recommended under divisions (C)(1)(a)1., (C)(1)(a)2. or (C)(1)(a)3. above, as appropriate, so that the structure is water-tight with walls substantially impermeable to the passage of water; and
2. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
(b) Upon completion of the structure, certification by a registered professional engineer or surveyor that the elevation requirements of the lowest floor, including basement, of this section have been satisfied shall be provided to the Floodplain Administrator for verification; or certification by a registered professional engineer or architect that the flood-proofing standards of this section are satisfied shall be provided to the Floodplain Administrator for verification.
(4) Accessory structures (detached garages and storage structures). Accessory structures used solely for parking of vehicles or storage may be constructed such that the floor is below the regulatory flood elevation; provided, the structure is designed and constructed in accordance with the following requirements.
(a) Use of the accessory structure must be limited to parking of vehicles or storage.
(b) The portions of the accessory structure located below the regulatory flood elevation must be built using flood resistant materials.
(c) The accessory structure must be adequately anchored to prevent flotation, collapse and lateral movement.
(d) Any machinery or equipment servicing the accessory structure must be elevated or flood-proofed to or above the regulatory flood elevation.
(e) The accessory structure must comply with floodway encroachment provisions in § 153.51 of this chapter.
(f) The accessory structure must be designed to allow for the automatic entry and exit of flood waters in accordance with divisions (C)(5)(a) or (C)(5)(b) below.
(g) Detached garages, storage structures and other accessory structures not meeting the above standards must be constructed in accordance with all applicable standards in divisions (C)(1)(a)1., (C)(1)(a)2. or (C)(1)(a)3. above, as appropriate.
(h) Upon completion of the structure, certification by a registered professional engineer, surveyor or local official that the requirements of this section have been satisfied shall be provided to the Floodplain Administrator for verification.
(5) Flood openings.
(a) All new construction and substantial improvement with fully enclosed areas below the lowest floor (excluding basements) that are usable solely for parking of vehicles, building access or storage and which are subject to flooding, shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of flood water.
(b) Designs for meeting this requirement must meet or exceed the following criteria for non-engineered openings:
1. Have a minimum of two openings, on different sides of each enclosed area, having 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 shall be no higher than one foot above grade;
3. Openings may be equipped with screens, louvers, valves or other coverings or devices provided that they permit the automatic entry and exit of flood water; or
4. Alternatively, a registered engineer or architect may design and certify engineered openings.
(6) Machinery and service equipment. All new construction, substantial improvement and other proposed new development shall be constructed with electrical, hearing, 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.
(7) Critical facilities construction. All new construction or substantial improvements of critical facilities shall have the lowest floor elevation either protected or elevated to protect the facility against the flood elevations of a 500-year flood event.
(Ord. 18-09, passed 7-24-2018)