(A) Residential construction. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated no lower than one foot above base flood elevation. Should solid foundation perimeter walls be used to elevate a structure, openings sufficient to facilitate the unimpeded movements of floodwaters shall be provided in accordance with the standards set forth in § 152.41(C).
(B) Nonresidential construction. New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall either have the lowest floor, including basement, elevated no lower than one foot above the level of the base flood elevation or, together with attendant utility and sanitary facilities, be flood-proofed so that all areas of the structure below the required elevation is watertight and 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. A registered professional engineer or architect shall certify that the standards of this division are satisfied. Such certification shall be provided to the official as set forth in § 152.31(C).
(C) Elevated buildings. New construction and substantial improvements of elevated buildings that include fully enclosed areas formed by foundation and other exterior walls below the base flood elevation shall be designed to preclude finished living space and designed to allow for the entry and exit of floodwaters to automatically equalize hydrostatic flood forces on exterior walls. Designs for complying with this requirement must either be certified by a professional engineer or architect or meet or exceed all of the following minimum criteria:
(1) Provide 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;
(2) The bottom of all openings shall be no higher than one foot above the higher of the interior or exterior grade immediately under the opening;
(3) Only the openings that are below the Base Flood Elevation (BFE) can be counted towards the required net open area;
(4) Openings may be equipped with screens, louvers, valves, or other coverings or devices provided they permit the automatic flow of floodwaters in both directions; and
(5) Fill placed around foundation walls must be graded so that the grade inside the enclosed area is equal to or higher than the adjacent grade outside the building on at least one side of the building.
(D) Hazardous velocities. Hydrodynamic pressure must be considered in the design of any foundation system where velocity waters or the potential for debris flow exists. If flood velocities are excessive (greater than five feet per second), foundation systems other than solid foundations walls should be considered so that obstructions to damaging flood flows are minimized.
(E) Enclosures below lowest floor.
(1) Access to the enclosed area shall be the minimum necessary to allow for parking of vehicles (garage door) or limited storage of maintenance equipment used in connection with the premises (standard exterior door) or entry to the living area (stairway or elevator).
(2) The interior portion of such enclosed area shall not be finished or partitioned into separate rooms, must be void of utilities except for essential lighting as required for safety, and cannot be temperature controlled.
(3) One wet location switch and/or outlet connected to a ground fault interrupt breaker may be installed below the required lowest floor elevation.
(4) All construction materials below the required lowest floor elevation should be flood resistant materials.
(F) Accessory structures.
(1) A detached accessory structure or garage, the cost of which is greater than $3,000, must comply with the requirements as outlined in FEMA's Technical Bulletin 7-93 Wet Floodproofing Requirements or be elevated or dry floodproofed.
(2) If accessory structures of $3,000 or less are to be placed in the floodplain, the following criteria shall be met:
(a) Accessory structures shall not be used for any uses other than the parking of vehicles and storage;
(b) Accessory structures shall be designed to have low flood damage potential;
(c) Accessory structures shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters;
(d) Accessory structures shall be firmly anchored to prevent flotation, collapse and lateral movement of the structure;
(e) Service facilities such as electrical and heating equipment shall be installed in accordance with this chapter;
(f) Openings to relieve hydrostatic pressure during a flood shall be provided below base flood elevation in conformance with this chapter; and
(g) Accessory structures shall be built with flood resistance materials in accordance with Technical Bulletin 2, Flood Damage-Resistant Materials Requirements, dated 8/08, and available from the Federal Emergency Management Agency. Class 4 and 5 materials, referenced therein, are acceptable flood-resistant materials.
(G) Swimming pool utility equipment rooms. If the building cannot be built at or above the BFE, because of functionality of the equipment then a structure to house the utilities for the pool may be built below the BFE with the following provisions:
(1) Meet the requirements for accessory structures.
(2) The utilities must be anchored to prevent flotation and shall be designed to prevent water from entering or accumulating within the components during conditions of the base flood.
(H) Elevators.
(1) Install a float switch system or another system that provides the same level of safety necessary for all elevators where there is a potential for the elevator cab to descend below the BFE during a flood per FEMA's Technical Bulletin 4-93 Elevator Installation for Buildings Located in Special Flood Hazard Areas.
(2) All equipment that may have to be installed below the BFE such as counter weight roller guides, compensation cable and pulleys, and oil buffers for traction elevators and the jack assembly for a hydraulic elevator must be constructed using flood-resistant materials where possible per FEMA's Technical Bulletin 4-93 Elevator Installation for Buildings Located in Special Flood Hazard Areas.
(I) Fill. An applicant shall demonstrate that fill is the only alternative to raising the building to meet the residential and non-residential construction requirements and that the amount of fill used will not affect the flood storage capacity or adversely affect adjacent properties. The following provisions shall apply to all fill placed in the special flood hazard area:
(1) Fill may not be placed in the floodway unless it is in accordance with the requirements of this chapter;
(2) Fill may not be placed in tidal or non-tidal wetlands without the required state and federal permits;
(3) Fill must consist of soil and rock materials only. A registered professional geotechnical engineer may use dredged material as fill only upon certification of suitability. Landfills, rubble fills, dumps, and sanitary fills are not permitted in the floodplain;
(4) Fill used to support structures must comply with ASTM Standard D-698, and its suitability to support structures certified by a registered, professional engineer;
(5) Fill slopes shall be no greater than two horizontal to one vertical. Flatter slopes may be required where velocities may result in erosion;
(6) The use of fill shall not increase flooding or cause drainage problems on neighboring properties;
(7) Fill may not be used for structural support in the coastal high hazard areas; and
(8) Will meet the requirements of FEMA Technical Bulletin 10-01, Ensuring That Structures Built On Fill in or Near Special Flood Hazard Areas Are Reasonable Safe from Flooding.
(Ord., passed 10-25-83; Am. Ord., passed 9-22-87; Am. Ord. 14-006, passed 2-25-14; Am. Ord. 2018-012, passed 8-28-18) Penalty, see § 152.99