In all areas of special flood hazard where base flood elevation data has been provided as set forth in section 10-4-4 of this chapter, the following provisions are required:
A. Residential Construction:
1. In AE and A1-30 zones or other A zoned areas where the BFE has been determined or can be reasonably obtained, new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated a minimum of one foot (1') above the base flood elevation. Mechanical equipment and utilities shall be waterproofed or elevated at least one foot above the BFE.
2. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or 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:
a. A minimum of two (2) 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.
b. The bottom of all openings shall be no higher than one foot (1') above grade.
c. Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
3. Below grade crawl spaces will not be considered basements if the following conditions are met:
a. The interior grade of a crawl space below the BFE must not be more than two feet (2') below the lowest adjacent exterior grade.
b. The height of the below grade crawl space, measured from the interior grade of the crawl space to the top of the floor joist must not exceed four feet (4') at any point.
c. There must be an adequate drainage system that removes floodwaters from the interior area of the crawl space. The enclosed area should be drained within a reasonable time after a flood event.
d. The velocity of floodwater at the site should not exceed five feet (5') per second.
e. Ductwork must either be placed above the BFE or sealed to prevent the entry of floodwaters.
f. The height of a below grade crawl space, measured from the interior grade of the crawl space to the top of the crawl space foundation wall shall not exceed four feet (4') at any point.
4. New construction and substantial improvement of any residential structure in an Unnumbered A zone for which a BFE is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the Highest Adjacent Grade.
5. New construction and substantial improvement of any residential structure in an AO zone shall meet the requirements in section 10-4-11.
6. New construction and substantial improvement of any residential structure in a V, V1-30, or VE zone shall meet the requirements in section 10-4-12.
7. A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of floodwaters.
Alternatively, a registered engineer or architect may design and certify engineered openings.
B. Nonresidential Construction: New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall meet the requirements of subsection 1 or 2, below.
1. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:
a. In AE and A1-30 zones or other A zoned areas where the BFE has been determined or can be reasonably obtained:
New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall have the lowest floor, including basement, elevated one foot or more above the BFE, or elevated as required by ASCE 24, whichever is greater. Mechanical equipment and utilities shall be waterproofed or elevated least one foot above the BFE, or as required by ASCE 24, whichever is greater.
b. If located in an AO zone, the structure shall meet the requirements in Section 10-4-11.
c. If located in an Unnumbered A zone for which a BFE is not available and cannot be reasonably obtained, the structure shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the Highest Adjacent Grade.
d. If located in a V, V1-30, or VE zone, the structure shall meet the requirements in Appendix B.
e. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall meet the requirements of subsection 10-4-8A2.
2. If the requirements of subsection B1 are not met, then new construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:
a. Be dry flood proofed so that below one foot or more above the base flood level the structure is watertight with walls substantially impermeable to the passage of water or dry flood proofed to the elevation required by ASCE 24, whichever is greater;
b. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
c. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this subsection based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the official as set forth in subsection 10-4-5B3.
d. Any below grade crawl space must comply with subsections A2a and A2f of this section.
Applicants who are flood proofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the flood proofed level (e.g. a building flood proofed to the base flood level will be rated as one foot below). Flood proofing the building an additional foot will reduce insurance premiums.
C. Manufactured Homes:
1. All manufactured homes to be placed or substantially improved on sites:
a. Outside of 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 the result of a flood;
shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated a minimum of one foot (1') above the base flood elevation and be securely anchored to an adequately designed foundation system to resist flotation, collapse, and lateral movement.
2. Manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision that are not subject to the above manufactured home provisions shall be elevated so that either:
a. The lowest floor of the manufactured home is elevated a minimum of one foot (1') above the base flood elevation; or
b. The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than thirty six inches (36") in height above grade and are securely anchored to an adequately designed foundation system to resist flotation, collapse, and lateral movement.
3. Any below grade crawl space must comply with subsections A2a and A2f of this section.
D. Recreational Vehicles: Recreational vehicles placed on sites are required to:
1. Be on the site for fewer than one hundred eighty (180) consecutive days; or
2. Be fully licensed and ready for highway use, on its wheels or jacking system, be attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or
3. Meet the requirements of subsection C of this section and the elevation and anchoring requirements for manufactured homes per subsection 10-4-7A2 of this chapter.
E. Enclosed Area Below the Lowest Floor: If buildings or manufactured homes are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage. (Ord. 847, 8-17-2009; amd. Ord. 909, 4-20-2015; Ord. 1016, 6-5-2023)