In all SFHAs, the following provisions are required.
(A) General. In addition to the requirements of § 154.25 of this chapter, all structures to be located in the SFHA shall be protected from flood damage below the FPG. This building protection requirement applies to the following situations:
(1) Construction or placement of any structure having a floor area greater than 400 square feet;
(2) Addition or improvement made to any existing structure where the cost of the addition or improvement equals or exceeds 50% of the value of the existing structure (excluding the value of the land);
(3) Reconstruction or repairs made to a damaged structure where the costs of restoring the structure to its before-damaged condition equals or exceeds 50% of the market value of the structure (excluding the value of the land) before damage occurred;
(4) Installing a travel trailer or recreational vehicle on a site for more than 180 days;
(5) Installing a manufactured home on a new site or a new manufactured home on an existing site. This chapter does not apply to returning the existing manufactured home to the same site it lawfully occupied before it was removed to avoid flood damage;
(6) Reconstruction or repairs made to a repetitive loss structure; and
(7) Addition or improvement made to any existing structure with a previous addition or improvement constructed since the community’s first floodplain ordinance.
(B) Residential structures. New construction or substantial improvement of any residential structure (or manufactured home) shall have the lowest floor; including basement, at or above the FPG (two feet above the base flood elevation). Should solid foundation perimeter walls be used to elevate a structure, openings sufficient to facilitate the unimpeded movements of flood waters shall be provided in accordance with the standards of division (D) below.
(C) Non-residential structures. New construction or substantial improvement of any commercial, industrial or non-residential structure (or manufactured home) shall either have the lowest floor, including basement, elevated to or above the FPG (two feet above the base flood elevation) or be flood- proofed to or above the FPG. Should solid foundation perimeter walk be used to elevate a structure, openings sufficient to facilitate the unimpeded movements of flood waters shall be provided in accordance with the standards of division (D) below. Structures located in all “A Zones” may be flood- proofed in lieu of being elevated if done in accordance with the following:
(1) A registered professional engineer or architect shall certify that the structure has been designed so that below the FPG, the structure and attendant utility facilities are watertight and capable of resisting the effects of the regulatory flood. The structure design shall take into account flood velocities, duration, rate of rise, hydrostatic pressures and impacts from debris or ice. Such certification shall be provided to the official as set forth in § 154.45(B)(12) of this chapter; and
(2) Flood-proofing measures shall be operable without human intervention and without an outside source of electricity.
(D) Elevated structures.
(1) New construction or substantial improvements of elevated structures shall have the lowest floor at or above the FPG.
(2) Elevated structures with fully enclosed areas formed by foundation and other exterior walls below the flood protection grade shall be designed to preclude finished living space and designed to allow for the entry and exit of flood waters to automatically equalize hydrostatic flood forces on exterior walls. Designs must meet the following minimum criteria:
(a) Provide a minimum of two openings, (in addition to doorways and windows), located in a minimum of two exterior walls (having a total net area of not less than one square inch for every one square foot of enclosed area);
(b) The bottom of all openings shall be no more than one foot above the exterior grade or the interior grade immediately beneath each opening, whichever is higher;
(c) Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of flood waters in both directions;
(d) Access to the enclosed area shall be the minimum necessary to allow for parking for 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);
(e) The interior portion of such enclosed area shall not be partitioned or finished into separate rooms; and
(f) The interior grade of such enclosed area shall be at an elevation at or higher than the exterior grade.
(E) Structures constructed on fill. A residential or non-residential structure may be constructed on a permanent land fill in accordance with the following.
(1) The fill shall be placed in layers no greater than one foot deep before compacting to 95% of the maximum density obtainable with either the Standard or Modified Proctor Test method. The results of the test showing compliance shall be retained in the permit file.
(2) The fill shall extend ten feet beyond the foundation of the structure before sloping below the BFE.
(3) The fill shall be protected against erosion and scour during flooding by vegetative cover, riprap or bulkheading. If vegetative cover is used, the slopes shall be no steeper than three horizontal to one vertical (3:1).
(4) The fill shall not adversely affect the flow of surface drainage from or onto neighboring properties.
(5) The top of the lowest floor including basements shall be at or above the FPG.
(F) Standards for manufactured homes and recreational vehicles. Manufactured homes and recreational vehicles to be installed or substantially improved on a site for more than 180 days must meet one of the following requirements.
(1) These requirements apply to all manufactured homes to be placed on a site outside a manufactured home park or subdivision; in a new manufactured home park or subdivision; in an expansion to an existing manufactured home park or subdivision; or in an existing manufactured home park or subdivision on which a manufactured home has incurred “substantial damage” as a result of a flood.
(a) The manufactured home shall be elevated on a permanent foundation such that the lowest floor shall be at or above the FPG and securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.
(b) Fully enclosed areas formed by foundation and other exterior walls below the FPG shall be designed to preclude finished living space and designed to allow for the entry and exit of flood waters to automatically equalize hydrostatic flood forces on exterior walls as required for elevated structures in division (D) above.
(c) Flexible skirting and rigid skirting not attached to the frame or foundation of a manufactured home are not required to have openings.
(2) These requirements apply to all manufactured homes to be placed on a site in an existing manufactured home park or subdivision that has not been substantially damaged by a flood:
(a) The manufactured home shall be elevated so that the lowest floor of the manufactured home chassis is supported by reinforced piers or other foundation elevations that are no less than 36 inches in height above grade and be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.
(b) Fully enclosed areas formed by foundation and other exterior walls below the FPG shall be designed to preclude finished living space and designed to allow for the entry and exit of flood waters to automatically equalize hydrostatic flood forces on exterior walls as required for elevated structures in division (D) above.
(c) Flexible skirting and rigid skirting not attached to the frame or foundation of a manufactured home are not required to have openings.
(3) Recreational vehicles placed on a site shall either:
(a) Be on site for less than 180 days;
(b) Be fully licensed and ready for highway use (defined as being on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices and has no permanently attached additions); or
(c) Meet the requirements for “manufactured homes” as stated earlier in this section.
(G) Accessory structures. Relief to the elevation or dry flood-proofing standards may be granted for accessory structures. Such structures must meet the following standards:
(1) Shall not be used for human habitation;
(2) Shall be constructed of flood resistant materials;
(3) Shall be constructed and placed on the lot to offer the minimum resistance to the flow of flood waters;
(4) Shall be firmly anchored to prevent flotation;
(5) Service facilities such as electrical and heating equipment shall be elevated or flood-proofed to or above the FPG; and
(6) Shall be designed to allow for the entry and exit of flood waters to automatically equalize hydrostatic flood forces on exterior walls as required for elevated structures in division (D) above.
(H) Above-ground gas or liquid storage tanks. All above-ground gas or liquid storage tanks shall be anchored to prevent flotation or lateral movement.
(Ord. 2015-003, passed 3-18-2015)