In all SFHAs and areas of suspected flood risk areas, 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 the BFE. A registered professional engineer, architect, or land surveyor shall submit certified elevations to the Floodplain Administrator that the standards of this chapter are satisfied.
(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 the base flood level, or together with attendant utility and sanitary facilities, be designed so that below 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) 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 subsection. A record of such certification that includes the specific elevation (in relation to mean sea level) to which such structures are floodproofed shall be maintained by the Floodplain Administrator.
(2) If the use or occupancy of the building changes in the future to residential, then the dry floodproofing of the structure cannot be used when determining compliance of the structure to the residential construction of this chapter, being division (A) above. 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.
(C) Enclosures. New construction and substantial improvements, with fully enclosed areas below the lowest floor that are to be used solely for parking of vehicles, building access, or storage in an area other than a basement, and 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. Designs for meeting this requirement must either be certified by a registered professional engineer or architect, or must meet or exceed the following minimum criteria:
(1) 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;
(2) The bottom of all openings shall be no higher than one foot above grade;
(3) 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
(4) The development and construction of the structure must conform with the provision in FEMA/Federal Insurance Administration (FIA)-Technical Bulletins 1 and 2. Certification and documentation from a professional, licensed engineer or architect is required if the structure’s lowest floor is built below the BFE.
(D) 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 1, 2, and 11, which include, but are not limited to, the following.
(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 vent opening can be no more than one foot above the lowest adjacent grade (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.
(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 any joists, insulation, piers, or other materials that extend below the BFE. Ductwork, in particular, must either be placed above the BFE or sealed from floodwaters.
(5) Any building utility systems within the crawlspace must be elevated above the BFE or 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 LAG.
(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 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.
(E) Manufactured homes.
(1) It is required that all manufactured homes to be placed within Zone A on a community’s FHBM or FIRM shall be installed using methods and practices that minimize flood damage.
(2) For the purposes of this requirement, manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement.
(3) Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces.
(2) It is required that manufactured homes that are placed or substantially improved within Zones A1-30, AH, and AE on the community’s FIRM on sites outside of 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, be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated as high as the BFE, and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.
(3) In A-1-30, AH, AO and AE Zones, it is required that manufactured homes to be placed or substantially improved in an existing manufactured home park to be elevated so that the lowest floor is at least as high as the BFE; or the chassis is supported by reinforced piers no less than 36 inches in height above grade and securely anchored.
(F) Recreational vehicles. It is required that recreational vehicles placed on sites within Zones A1-30, AH, and AE on the community’s FIRM either:
(1) Be on the site for fewer than 180 consecutive days and be fully licensed and ready for highway use; 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; and
(2) Or meet the permit requirements of § 154.268(D), and the elevation and anchoring requirements for “manufactured homes” of this section.
(Ord. 842, passed 3-14-2022)