In all SFHAs, the following provisions are required:
(A) All structures. In addition to the requirements of § 154.40, 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 new structure having a floor area greater than 400 square feet;
(2) Structural alterations made to:
(a) An existing (previously unaltered structure), the cost of which equals or exceeds 50% of the value of the pre-altered structure (excluding the value of the land);
(b) Any previously altered structure;
(3) Reconstruction or repairs made to a damaged structure that are valued at more than 50% of the market value of the structure (excluding the value of the land) before damaged 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; and
(6) Reconstruction or repairs made to a repetitive loss structure.
(B) Residential construction. 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 floodwaters shall be provided in accordance with the standards of § 154.41(D).
(C) Non-residential construction. New construction or substantial improvement of any commercial, industrial, or nonresidential structure (or manufactured home) shall have the lowest floor, including basement, elevated to or above the FPG (two feet above the base flood elevation). Structures located in all “A Zones” may be floodproofed 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 § 154.27(B)(10).
(2) Floodproofing 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 that include fully enclosed areas formed by foundation and other exterior walls below the base flood elevations 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.
(2) Designs for complying with this requirement must either be certified by a professional engineer or architect or meet the follow minimum criteria:
(a) 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;
(b) The bottom of all openings shall be no higher than one foot above foundation interior grade (which must be equal to in elevation or higher than the exterior foundation grade);
(c) Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwaters 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); and
(e) The interior portion of such enclosed area shall not be partitioned or finished into separate rooms.
(E) Structures constructed on fill. A residential or nonresidential 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 1 foot deep before compacting to 95% of the maximum density obtainable with the standard proctor test method.
(2) The fill should extend at least ten feet beyond the foundation of the structure before sloping below the FPG.
(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.
(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 structures constructed with a crawlspace. A residential or nonresidential structure may be constructed with a crawlspace located below the flood protection grade provided that the following conditions are met:
(1) The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.
(2) Any enclosed area below the flood protection grade shall have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. A minimum of one opening on each wall having a total net area of not less than one square inch for every one square foot of enclosed area. The bottom of the openings shall be no more than one foot above grade.
(3) The interior grade of the crawlspace must be at or above the base flood elevation.
(4) The interior height of the crawlspace measured from the interior grade of the crawlspace to the top of the foundation wall must not exceed four feet at any point.
(5) An adequate drainage system must be installed to remove floodwaters from the interior area of the crawlspace within a reasonable period of time after a flood event.
(6) Portions of the building below the flood protection grade must be constructed with materials resistant to flood damage.
(7) Utility systems within the crawlspace must be elevated above the flood protection grade.
(G) 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) 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. This requirement applies to all manufactured homes to be placed on a site:
(a) Outside a manufactured home park or subdivision;
(b) In a new manufactured home park or subdivision;
(c) In an expansion to an existing manufactured home park or subdivision; or
(d) In an existing manufactured home park or subdivision on which a manufactured home has incurred “substantial damage” as a result of a flood.
(2) 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. This requirement applies 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.
(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.
(Ord. 2017-04, passed 4-25-2017)