Specific standards apply to all areas of special flood hazards, including the following required standards.
(A) Residential construction.
(1) (a) New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to the flood protection elevation (FPE).
(b) Minimum FEMA standards require the lowest floor to be elevated “to or above” the BFE; however, adding an additional foot of freeboard increases safety and can reduce insurance premiums by as much as 30%.
(c) Additional freeboard is strongly encouraged by FEMA and the city.
(2) All new construction or substantial improvement of an existing structure, including a structure that has been substantially damaged, that includes a fully-enclosed area located below the lowest floor formed by the foundation and other exterior walls shall be designed to be an unfinished or flood- resistant enclosure. The enclosure shall be designed to equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwater.
(a) Designs for complying with this requirement must be certified by a licensed professional engineer or architect or meet the following minimum criteria:
1. Provide a minimum of two openings with a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;
2. The bottom of all openings shall be no higher than one foot above the higher of the exterior or interior grade or floor immediately below the opening; and
3. Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided, they permit the automatic flow of floodwater in both directions without manual intervention.
(b) To comply with the “lowest floor” criteria of this chapter, the unfinished or flood- resistant enclosure shall only be used for the parking of vehicles, limited storage of maintenance equipment used in connection with the premises, or entry to the elevated area.
(c) The interior portion of such enclosed area shall not be partitioned or finished into separate rooms.
(d) For crawlspace-foundation types, construction must follow the guidelines in FEMA TB 11-01, Crawlspace Construction for Structures Located in Special Flood Hazard Areas: National Flood Insurance Program Guidance, specifically:
1. Below-grade crawlspaces are prohibited at sites where the velocity of floodwaters exceed five feet per second;
2. Interior grade of the crawlspace below the BFE must not be more than two feet below the lowest adjacent exterior grade (LAG);
3. Height of the below-grade crawlspace, measured from the lowest interior grade of the crawlspace to the bottom of the floor joist, must not exceed four feet at any point; and
4. Contain an adequate drainage system that removes floodwaters from the interior area of the crawlspace.
(B) Nonresidential construction. New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall either have the lowest floor, including the basement, elevated to the flood protection elevation; or, together with attendant utility and sanitary facilities, shall:
(1) Be floodproofed one foot or more above the base flood level so that the structure is watertight with walls substantially impermeable to the passage of water;
(2) Have structural components capable of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy;
(3) 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 section 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 § 152.26(B)(3)(b); and
(4) (a) Applicants who are floodproofing nonresidential buildings should be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building floodproofed to the base flood level will be rated as one foot below).
(b) Floodproofing the building an additional foot will reduce insurance premiums significantly.
(C) Manufactured homes.
(1) (a) All manufactured homes in the floodplain to be placed or substantially improved on sites shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to the flood protection elevation and be securely anchored to an adequately-anchored foundation system to resist flotation, collapse, and lateral movement.
(b) All manufactured homes in the floodplain need to minimize flood damage within the flood prone area.
(2) In all areas of special flood hazard where the base flood elevation has not been established, manufactured homes placed, substantially improved, or having incurred substantial damage must be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated two feet above the highest adjacent grade and be securely anchored to an adequately-anchored foundation system to resist flotation, collapse, and lateral movement.
(3) Manufactured homes placed on solid perimeter walls shall meet the flood vent requirements in division (A)(2) above, except when the first floor, including enclosed areas and crawlspace, is located above the base flood elevation.
(D) Recreational vehicles. Recreational vehicles placed on sites are required to either:
(1) Be on the site for fewer than 180 consecutive days;
(2) Be fully licensed and ready for highway use, on wheels or jacking system, attached to the site only by quick disconnect-type utilities and security devices, and have no permanently attached additions; and/or
(3) Meet the requirements of division (C) above and the elevation and anchoring requirements for manufactured homes.
(E) Critical facility.
(1) Construction of new critical facilities shall be, to the extent possible, located outside the limits of the special flood hazard area (SFHA, or 100-year floodplain).
(a) Construction of new critical facilities shall be permissible within the SFHA if no feasible alternative site is available.
(b) Critical facilities constructed within the SFHA shall have the lowest floor elevated three feet above BFE or to the height of the 500-year flood, whichever is higher.
(2) Access to and from the critical facility should also be protected to the height utilized above.
(3) Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters.
(4) Access routes elevated to or above the level of the base flood elevation shall be provided to all critical facilities to the extent possible.
(Prior Code, § 14-1-5) (Ord. 2015-02, passed 6-10-2015) Penalty, see § 152.99
Statutory reference:
Flood hazard standards, see 44 C.F.R. § 60.3(c)(1)
Manufactured homes, see 44 C.F.R. § 60.3(c)(6)(12)
Nonresidential construction, see 44 C.F.R. § 60.3(c)(3)(4)
Recreational vehicles, see 44 C.F.R. § 60.3(c)(14)
Residential construction, see 44 C.F.R. § 60.3(c)(2)(5)