New residential structures and residential portions of mixed use structures, and substantial improvement (including repair of substantial damage) of existing residential structures and residential portions of mixed use structures shall comply with the applicable requirements of §§ 81-19 through 81-30 and this section. See § 81-36 for requirements for horizontal additions.
(A) Elevation requirements.
(1) Lowest floors shall be elevated to or above the flood protection elevation.
(2) In areas of shallow flooding (Zone AO), the lowest floor (including basement) shall be elevated at least as high above the highest adjacent grade as the depth number specified in feet on the FIRM plus two feet, or at least four feet if a depth number is not specified.
(3) Enclosures below the lowest floor shall meet the requirements of division (C) below.
(B) Limitations on use of fill to elevate structures. Unless otherwise restricted by these regulations, especially by the limitations in § 81-15(A), (B) and (C), fill placed for the purpose of raising the ground level to support a building or structure shall:
(1) Consist of earthen soil or rock materials only.
(2) Extend laterally from the building footprint to provide for adequate access as a function of use; the Floodplain Administrator may seek advice from the State Fire Marshal's Office and/or the local fire services agency;
(3) Comply with the requirements of the building code and be placed and compacted to provide for stability under conditions of rising and falling floodwaters and resistance to erosion, scour, and settling;
(4) Be sloped no steeper than one vertical to two horizontal, unless approved by the Floodplain Administrator;
(5) Be protected from erosion associated with expected velocities during the occurrence of the base flood; unless approved by the Floodplain Administrator, fill slopes shall be protected by vegetation if the expected velocity is less than five feet per second, and by other means if the expected velocity is five feet per second or more; and
(6) Be designed with provisions for adequate drainage and no adverse effect on adjacent properties.
(C) Enclosures below the lowest floor.
(1) Enclosures below the lowest floor shall be used solely for parking of vehicles, building access, crawl/underfloor spaces, or limited storage.
(2) Enclosures below the lowest floor shall be constructed using flood damage-resistant materials.
(3) Enclosures below the lowest floor shall be provided with flood openings which shall meet the following criteria: [Note: See NFIP Technical Bulletin #1, "Openings in Foundation Walls and Walls of Enclosures Below Elevated Buildings."]
(a) There shall be a minimum of two flood openings on different sides of each enclosed area; if a building has more than one enclosure below the lowest floor, each such enclosure shall have flood openings on exterior walls.
(b) The total net area of all flood openings shall be at least one square inch for each square foot of enclosed area (non-engineered flood openings), or the flood openings shall be engineered flood openings that are designed and certified by a licensed professional engineer to automatically allow entry and exit of floodwaters; the certification requirement may be satisfied by an individual certification or an evaluation report issued by the ICC Evaluation Service, Inc.
(c) The bottom of each flood opening shall be one foot or less above the higher of the interior floor or grade, or the exterior grade, immediately below the opening.
(d) Any louvers, screens or other covers for the flood openings shall allow the automatic flow of floodwaters into and out of the enclosed area.
(e) If installed in doors, flood openings that meet requirements of division (C)(3)(a) through (d) above, are acceptable; however, doors without installed flood openings do not meet the requirements of this section.
(Ord. 02-2014, passed 4-21-2014)