In all areas of special flood hazard where base flood elevation data or flood depths have been provided, as set forth in § 152.07 the following provisions are required:
(A) Building protection requirement. In addition to the general standards described in § 152.41, 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 a residential structure;
(2) Construction or placement of a non-residential structure;
(3) Addition or improvement made to an existing structure where the cost of the addition or improvement equals or exceeds fifty percent (50%) of the value of the existing structure (excluding the value of the land). An addition and/or improvement project that is continuous in scope or time is considered as one project for permitting purposes;
(4) Reconstruction or repairs made to a damaged structure where the costs of restoring the structure to its before damaged condition equals or exceeds fifty percent (50%) of the market value of the structure (excluding the value of the land) before damage occurred (the costs of any proposed additions or improvements beyond restoring the damaged structure to its before damaged condition must be included in the cost);
(5) Installing manufactured home on a new site or a new manufactured home on an existing site;
(6) Installing a travel trailer or recreational vehicle on a site for more than one hundred eighty (180) days;
(7) Reconstruction or repairs made to a repetitive loss structure; and
(8) Addition or improvement made to any existing structure with a previous repair, addition or improvement constructed since the community’s first floodplain ordinance.
(B) Residential construction.
(2) In Zone A and Zone AE, new construction or substantial improvement of any residential structure shall have the lowest floor; including basement, at or above the FPG. 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 § 152.42(B)(3). Should fill be used to elevate a structure, the standards of § 152.42(B)(4) must be met.
(3) Fully enclosed areas formed by foundation and other exterior walls below the flood protection grade shall meet the following requirement:
(a) Designed to preclude finished living space and designed to allow for the automatic entry and exit of floodwaters to equalize hydrostatic flood forces on exterior walls. Flood openings must be designed and installed in compliance with criteria set out in FEMA Technical Bulletin 1. Engineered flood openings must be designed and certified by a registered design professional (requires supporting engineering certification or make/model specific ICC-ES Report), or meet the following criteria for non-engineered flood openings:
1. Provide a minimum of two (2) openings on different sides of an enclosure, having a total net area of not less than one (1) square inch for every square foot of enclosed area. If there are multiple enclosed areas, each is required to meet the requirements for enclosures, including the requirement for flood openings in exterior walls.
2. The bottom of all openings shall be no more than one (1) foot above the higher of the final interior grade (or floor) and the finished exterior grade immediately under each opening;
3. If the floor of the enclosure is below the BFE, the openings must be located wholly below the BFE.
4. If the floor of the enclosure is at or above the BFE, but below the FPG, the openings must be located wholly below the FPG;
5. Doors and windows do not qualify as openings;
6. Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwaters in both directions;
7. Openings are to be not less than three (3) inches in any direction in the plane of the wall. This requirement applies to the hole in the wall, excluding any device that may be inserted such as typical foundation air vent device.
(b) The floor of such enclosed area must be at or above grade on at least one side.
(4) A residential structure may be constructed on a fill in accordance with the following:
(a) Fill shall be placed in layers no greater than one (1) foot deep before compacting to ninety-five percent (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;
(b) Fill shall extend ten (10) feet beyond the foundation of the structure before sloping below the BFE;
(c) Fill shall be protected against erosion and scour during flooding by vegetative cover, riprap, or bulk heading. If vegetative cover is used, the slopes shall be no steeper than three (3) feet horizontal to one (1) foot vertical;
(d) Fill shall not adversely affect the flow of surface drainage from or onto neighboring properties;
(e) Fill shall be composed of clean granular or earthen material.
(5) A residential structure may be constructed using a stem wall foundation (also called chain wall, raised-slab-on-grade, and slab-on-stem-wall-with-fill). Any backfilled stem wall foundation (also called chain wall, raised-slab-on-grade, and slab-on-stem-wall-with-fill) must be backfilled with compacted structural fill, concrete, or gravel that supports the floor slab. No flood openings are required for this type of construction.
(C) Non-residential construction.
(2) In Zone A and Zone AE, new construction, or substantial improvement of any commercial, industrial, or non-residential structure (excludes accessory structures) shall either have the lowest floor, including basement, elevated to or above the FPG or be floodproofed to or above the FPG. 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 § 152.42(C)(3). Should fill be used to elevate a structure, the standards of § 152.42(C)(4) must be met.
(3) Fully enclosed areas formed by foundation and other exterior walls below the flood protection grade shall meet the following requirement:
(a) Designed to preclude finished living space and designed to allow for the automatic entry and exit of floodwaters to equalize hydrostatic flood forces on exterior walls. Flood openings must be designed and installed in compliance with criteria set out in FEMA Technical Bulletin 1. Engineered flood openings must be designed and certified by a registered design professional (requires supporting engineering certification or make/model specific ICC-ES Report), or meet the following criteria for non-engineered flood openings:
1. Provide a minimum of two (2) openings on different sides of an enclosure, having a total net area of not less than one (1) square inch for every one (1) square foot of enclosed area. If more than one (1) enclosed area is present, each must have openings on exterior walls;
2. The bottom of all openings shall be no more than one (1) foot above the higher of the final interior grade (or floor) and the finished exterior grade immediately under each opening;
3. Doors and windows do not qualify as openings;
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;
5. Openings are to be not less than three (3) inches in any direction in the plane of the wall. This requirement applies to the hole in the wall, excluding any device that may be inserted such as typical foundation air vent device.
(b) The floor of such enclosed area must be at or above grade on at least one (1) side.
(c) The interior portion of such enclosed area shall not be partitioned or finished into separate rooms.
(4) A nonresidential structure may be constructed on a fill in accordance with the following:
(a) Shall be placed in layers no greater than one (1) foot deep before compacting to ninety-five percent (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;
(b) Shall extend ten (10) feet beyond the foundation of the structure before sloping below the BFE;
(c) Shall be protected against erosion and scour during flooding by vegetative cover, riprap, or bulk heading. If vegetative cover is used, the slopes shall be no steeper than three (3) feet horizontal to one (1) foot vertical;
(d) Shall not adversely affect the flow of surface drainage from or onto neighboring properties;
(e) Shall be composed of clean granular or earthen material.
(5) A nonresidential structure may be floodproofed in accordance with the following:
(a) 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 Floodplain Administrator.
(b) Floodproofing measures shall be operable without human intervention and without an outside source of electricity.
(6) A nonresidential structure may be constructed using a stem wall foundation (also called chain wall, raised-slab-on-grade, and slab-on-stem-wall-with-fill). Any backfilled stem wall foundation must be backfilled with compacted structural fill, concrete, or gravel that supports the floor slab. No flood openings are required for this type of construction.
(D) Manufactured homes and recreational vehicles.
(1) These requirements apply to all manufactured homes to be placed on a site in the SFHA:
(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 floodwaters to automatically equalize hydrostatic flood forces on exterior walls as required for elevated structures in § 152.42(B)(3).
(c) Flexible skirting and rigid skirting not attached to the frame or foundation of a manufactured home are not required to have openings.
(2) Recreational vehicles placed on a site in the SFHA shall either:
(a) Be on site for less than one hundred eighty (180) days and be fully licensed and ready for use on a public highway (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
(b) Meet the requirements for manufactured homes as stated earlier in this section.
(E) Accessory structures. Within SFHAs, new construction or placement of an accessory structure must meet the following standards:
(1) Shall have a floor area of four hundred (400) square feet or less;
(2) Use shall be limited to parking of vehicles and limited storage;
(3) Shall not be used for human habitation;
(4) Shall be constructed of flood resistant materials;
(5) Shall be constructed and placed on the lot to offer the minimum resistance to the flow of floodwaters;
(6) Shall be firmly anchored to prevent flotation;
(7) Service facilities such as electrical and heating equipment shall be elevated or floodproofed to or above the FPG;
(8) Shall be designed to allow for the entry and exit of floodwaters to automatically equalize hydrostatic flood forces on exterior walls as required for elevated structures in § 152.42(C)(3); and
(9) Shall not have subsequent additions or improvements that would preclude the structure from its continued designation as an accessory structure.
(F) Free-standing pavilions, gazebos, decks, carports, and similar development. Within SFHAs, new construction or placement of free-standing pavilions, gazebos, decks, carports, and similar development must meet the following standards:
(1) Shall have open sides (having not more than one (1) rigid wall);
(2) Shall be anchored to prevent flotation or lateral movement;
(3) Shall be constructed of flood resistant materials below the FPG;
(4) Any electrical, heating, plumbing and other service facilities shall be located at/above the FPG;
(5) Shall not have subsequent additions or improvements that would preclude the development from its continued designation as a free-standing pavilion, gazebo, carport, or similar open-sided development.
(G) Above ground gas or liquid storage tanks. Within SFHAs, all newly placed aboveground gas or liquid storage tanks shall meet the requirements for a non-residential structure as required in § 152.42(C).
(Ord. 2022-11, passed 6-9-22)