In all areas of flood hazard where base flood elevation data has been provided as set forth in this chapter, the following provisions are required:
(A) Residential construction. New construction and substantial improvement of any residential structure shall have the lowest floor (including basement), elevated to at least two feet above the base flood elevation. A registered professional engineer, architect, or land surveyor shall certify to the Floodplain Administrator that the elevation standard has been satisfied. Properties that have received a letter of map amendment or letter of map revision based upon fill must have the lowest structure opening elevated to two feet above the base flood elevation and conform to the provisions of this section and FEMA/FIA-TB-10.01.
(B) Non-residential construction. New construction and substantial improvements of any commercial, industrial, or other non-residential structure shall either have the lowest floor (including basement) elevated to at least two feet above the base flood level or, together with attendant utility and sanitary facilities, be designed so that below two feet above the base flood level the structure is watertight 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.
(1) New construction and substantial improvements of any commercial, industrial, or other non-residential structure, including, but not limited to, detached garages, agricultural buildings, and storage buildings, may be allowed to be wet floodproofed, provided that:
(a) The structure is strictly a non-residential structure used only for building access, parking, or storage;
(b) The structure is an accessory structure of low value;
(c) The structure is designed to allow for the automatic entry and exit of floodwaters through the use of flood openings;
(d) The structure is constructed of flood resistant materials;
(f) The structure is properly anchored to resist flotation, collapse, and lateral movement;
(e) The structure’s mechanical and utility equipment is elevated or floodproofed to at least two feet or more above the BFE;
(g) The structure is compliant with the floodway encroachment provisions of the NFIP and this chapter; and
(h) The structure is designed and built to adhere to FEMA Technical Bulletins No. 1, 2, and 7.
(2) (a) A registered professional engineer or architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with accepted standards of practice as outlined in this division (B).
(b) A record of such certification which includes the specific elevation (in relation to mean sea level) to which such structures are flood proofed shall be maintained by the Floodplain Administrator.
(3) (a) If the use or occupancy of the building changes in the future to be considered residential, then the floodproofing of the structure cannot be used when determining compliance of the structure to the residential construction requirements of this chapter.
(b) As such, the building will not be grandfathered into compliance and will be required to be brought into compliance with the residential construction requirements of this chapter.
(4) Properties that have received a letter of map amendment or letter of map revision based upon fill must have the lowest structure opening elevated to two feet above the base flood elevation and conform to the provisions of this section and FEMA/FIA-TB-10.
(C) Enclosures.
(1) New construction or substantial improvements, excluding crawl spaces, with fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access, or storage in an area other than a basement, and which are subject to flooding, shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters.
(2) Designs for meeting this requirement must either be certified by a registered professional engineer or architect, or meet or exceed the following minimum criteria:
(a) 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 shall be provided, or be designed by a professional engineer to be of equal capacity;
(b) The bottom of all openings shall be no higher than one foot above grade;
(c) Openings may be equipped with screens, louvers, valves, or other coverings or devices, provided that they permit the automatic entry and exit of floodwaters; and
(d) The bottom of the floor joists of the structure’s lowest floor shall be at least two feet above the BFE.
(3) The development and construction of the structure must conform with the provisions in FEMA/Federal Insurance Administration (FIA) Technical Bulletins No. 1 and 2.
(4) For any non-residential construction that has an enclosure, a non-conversion agreement must be completed as part of the permitting process. The non-conversion agreement:
(a) Acknowledges the risk associated with this building practice;
(b) Acknowledges that the area was permitted as an enclosure and shall only be used as a non-residential accessory of low value for the purpose of building access, parking, or storage; and
(c) Allows for community, state, and/or federal officials to conduct periodic inspections to ensure compliance.
(D) Manufactured homes.
(1) All new and replacement manufactured homes to be placed or substantially improved in a flood hazard area shall be elevated such that the lowest floor of the manufactured home is elevated to at least two feet above the base flood elevation.
(2) All new and replacement manufactured homes, including substantial improvement of existing manufactured homes, shall be placed on a permanent, reinforced foundation (including pile or column foundations) that is adequately anchored to resist flotation, collapse, and lateral movement due to the effects of wind and flood loads acting simultaneously on all building components.
(E) Recreational vehicles.
(1) For temporary placement, recreational vehicles in flood hazard areas shall be fully licensed and ready for highway use, and shall be placed on a site for less than 180 consecutive days. A recreational vehicle is ready for highway use if it is 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.
(2) For permanent placement, recreational vehicles that are not ready for highway use or that are to be placed on a site for more than 180 consecutive days shall meet the requirements of § 153.067 for manufactured homes.
(F) Crawlspace. New construction and substantial improvements built on a crawlspace or sub-grade (below grade) crawlspace may be permitted if the development is designed and meets or exceeds the standards found in FEMA’s Technical Bulletins No. 1, 2, and 11, which include, but are not limited to, the following provisions.
(1) The structure must be affixed to a permanent foundation, 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. Because of hydrodynamic loads, crawlspace construction is not allowed in areas with flood velocities greater than five feet per second, unless the design is reviewed by a qualified design professional, such as a registered architect or professional engineer.
(2) The crawlspace is an enclosed area below the BFE and, as such, must have openings that equalize hydrostatic pressures by allowing the automatic entry and exit of floodwaters. The bottom of each flood opening can be no more than one foot above the LAG.
(3) The crawlspace enclosure must have proper openings that allow equalization of hydrostatic pressure by allowing automatic entry and exit of floodwaters. To achieve this, a minimum of one square inch of flood opening is required per one square foot of the enclosed area subject to flooding. A registered professional engineer must certify the elevation, design, and location of flood openings.
(4) Portions of the building below the BFE must be constructed with materials resistant to flood damage. This includes not only the foundation walls of the crawlspace used to elevate the building, but also insulation, piers, or other materials that extend below two foot above the BFE. Floor joists and ductwork must be placed two feet above the BFE.
(5) Any building utility systems within the crawlspace must be elevated two feet above the BFE, or be designed so that floodwaters cannot enter or accumulate within the system components during flood conditions.
(6) The interior grade of a crawlspace below the BFE must not be more than two feet below the lowest adjacent exterior grade.
(7) The height of the below-grade crawlspace, measured from the lowest interior grade of the crawlspace floor to the bottom of the floor joist of the next higher floor cannot exceed four feet at any point.
(8) There must be an adequate drainage system that removes floodwaters from the interior area of the crawlspace. The enclosed area should be drained within a reasonable time after a base flood event.
(9) Buildings with below-grade crawlspaces will have higher flood insurance premiums than buildings that have the preferred crawlspace construction, with the interior elevation at or above the LAG.
(Ord. 2016-34, passed 6-22-2021)