(A) General standards. In all SFHAs the following provisions are required:
(1) New construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure;
(2) Manufactured homes shall be anchored to prevent flotation, collapse or lateral movement. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors. This standard shall be in addition to and consistent with applicable state requirements for resisting wind forces;
(3) New construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage below the FPG;
(4) New construction and substantial improvements shall be constructed by methods and practices that minimize flood damage;
(5) Electrical, heating, ventilation, plumbing, air conditioning equipment and other service facilities shall be designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding;
(6) New and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system;
(7) New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the system;
(8) On-site waste disposal systems shall be located and constructed to avoid impairment to them or contamination from them during flooding;
(9) Any alteration, repair, reconstruction or improvements to a structure that is in compliance with the provisions of this subchapter shall meet the requirements of "new construction" as contained in this subchapter;
(10) Any alteration, repair, reconstruction or improvement to a structure that is not in compliance with the provisions of this subchapter, shall be undertaken only if the non-conformity is not further, extended or replaced; and
(11) Whenever any portion of the SFHA is authorized for use, the volume of space which will be occupied by the authorized fill or structure below the BFE shall be compensated for and balanced by an equivalent volume of excavation taken below the BFE. The excavation volume shall be at least equal to the volume of storage lost (replacement ratio of 1 to 1) due to the fill or structure.
(a) The excavation shall take place in the floodplain and in the same immediate watershed in which the authorized fill or structure is located.
(b) Under certain circumstances, the excavation may be allowed to take place outside of but adjacent to the floodplain provided that the excavated volume will be below the regulatory flood elevation, will be in the same immediate watershed in which the authorized fill or structure is located, will be accessible to the regulatory flood water, will not be subject to ponding when not inundated by flood water, and that it shall not be refilled.
(c) The fill or structure shall not obstruct a drainage way leading to the floodplain.
(d) The fill or structure shall be of a material deemed stable enough to remain firm and in place during periods of flooding and shall include provisions to protect adjacent property owners against any increased runoff or drainage resulting from its placement.
(e) Plans depicting the areas to be excavated and filled shall be submitted prior to the actual start of construction or any site work; once site work is complete, but before the actual start of construction, the applicant shall provide to the Floodplain Administrator a certified survey of the excavation and fill sites demonstrating the fill and excavation comply with this subchapter.
(B) Specific standards. In all SFHAs, the following provisions are required:
(1) In addition to the requirements of § 151.34, 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: (a) Construction or placement of any new structure having a floor area greater than 400 square feet;
(b) Structural alterations made to:
1. 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); and/or
2. Any previously altered structure.
(c) 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;
(d) Installing a travel trailer or recreational vehicle on a site for more than 180 days;
(e) Installing a manufactured home on a new site or a new manufactured home on an existing site. This subchapter 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
(f) Reconstruction or repairs made to a repetitive loss structure.
(2) New construction or substantial improvement of any residential structure (or manufactured home) shall have the lowest floor; including basement, at or above the FPG (2 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 division (B)(4) below.
(3) New construction or substantial improvement of any commercial, industrial or non-residential structure (or manufactured home) shall have the lowest floor, including basement, elevated to or above the FPG (2 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:
(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. Certification shall be provided to the official as set forth in § 151.32(C)(10); and (b) Floodproofing measures shall be operable without human intervention and without an outside source of electricity.
(4) 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. 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 2 openings having a total net area of not less than 1 square inch for every square foot of enclosed area subject to flooding;
(b) The bottom of all openings shall be no higher than 1 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);
(e) The interior portion of the enclosed area shall not be partitioned or finished into separate rooms; and
(f) Where elevation requirements exceed 6 feet above the highest adjacent grade, a copy of the legally recorded deed restriction prohibiting the conversion of the area below the lowest floor to a use or dimension contrary to the structure's originally approved design, shall be presented as a condition of issuance of the final certificate of occupancy.
(5) A residential or nonresidential structure may be constructed on a permanent land fill in accordance with the following:
(a) 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;
(b) The fill should extend at least 10 feet beyond the foundation of the structure before sloping below the FPG;
(c) 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 3 horizontal to 1 vertical;
(d) The fill shall not adversely affect the flow of surface drainage from or onto neighboring properties; and
(e) The top of the lowest floor including basements shall be at or above the FPG.
(6) A residential or nonresidential structure may be constructed with a crawlspace located below the flood protection grade provided that the following conditions are met:
(a) 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;
(b) 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 1 opening on each wall having a total net area of not less than 1 square inch for every 1 square foot of enclosed area. The bottom of the openings shall be no more than 1 foot above grade;
(c) The interior grade of the crawlspace must be at or above the base flood elevation;
(d) The interior height of the crawlspace measured from the interior grade of the crawlspace to the top of the foundation wall must not exceed 4 feet at any point;
(e) 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;
(f) Portions of the building below the flood protection grade must be constructed with materials resistant to flood damage; and
(g) Utility systems within the crawlspace must be elevated above the flood protection grade.
(7) Manufactured homes and recreational vehicles to be installed or substantially improved on a site for more than 180 days must meet 1 of the following requirements:
(a) The manufactured home shall be elevated on a permanent foundation so 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:
1. Outside a manufactured home park or subdivision;
2. In a new manufactured home park or subdivision;
3. In an expansion to an existing manufactured home park or subdivision; or
4. In an existing manufactured home park or subdivision on which a manufactured home has incurred "substantial damage" as a result of a flood.
(b) 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.
(c) Recreational vehicles placed on a site shall either:
1. Be on site for less than 180 days; and
2. 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
3. Meet the requirements for "manufactured homes" as stated earlier in this section.
