(A) Residential structures.
(1) In Zones A, AE, A1-30, and AH, all new construction and substantial improvements shall have the lowest floor, including basement, elevated to or above one foot above the base flood elevation. Mechanical equipment including those associated with utilities, such as but not limited to electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities shall also be elevated to or above one foot above base flood elevation.
(2) In Zone AO, all new construction and substantial improvements shall have the lowest floor, including basement, elevated above the highest adjacent grade at least as high as one foot above the depth number specified in feet on the FIRM or, if no depth number is specified on the FIRM, at least as high as three feet. Mechanical equipment including those associated with utilities, such as but not limited to electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities, shall also be elevated to or above the one foot above base flood elevation.
(3) In the floodway, new structures for human habitation are prohibited.
(B) Nonresidential structures.
(1) In Zones A, AE, A1-30, and AH, all new construction and substantial improvements shall have the lowest floor, including basement, mechanical equipment including those associated with utilities, such as but not limited to electrical, heating, ventilation, plumbing, and air condition equipment and other service facilities shall be elevated to or above one foot above the base flood elevation.
(2) A registered professional engineer or architect shall certify that the standards of this section are satisfied. A floodproofing certificate shall be provided to the floodplain administrator as set forth in § 25-12-14.
(3) (a) Zone AO areas have special flood hazards associated with base flood depths of one to three feet where a clearly defined channel does not exist and where the path of flooding is unpredictable and indeterminate. In Zone AO all new construction and substantial improvements shall have the lowest floor, and mechanical equipment including those associated with utilities, such as but not limited to electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities shall be elevated above the highest adjacent grade at least as high as one foot above the depth number specified in feet on the FIRM or, if no depth number is specified on the FIRM, at least as high as three feet; or, together with attendant utility and sanitary facilities, floodproofed so that below one foot above the base flood elevation:
(b) Adequate drainage paths around structures on slopes shall be required in order to guide floodwaters around and away from proposed structures. A registered professional engineer or architect shall certify that the standards of this section are satisfied. A floodproofing certificate shall be provided to the floodplain administrator as set forth in § 25-12-14.
(C) Space below lowest floor.
(1) Fully enclosed areas below the lowest floor (excluding basements) and below the base flood elevation shall be used solely for the parking of vehicles, building access, or limited storage of readily removable items.
(2) Fully enclosed areas below the lowest floor (excluding basements) and below the base flood elevation 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 meet or exceed the following minimum criteria:
(a) A minimum or two openings having a net total area of not less than one square inch for every one square foot of enclosed space;
(b) The bottom of all openings shall not be higher than one foot above grade; and
(c) Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they allow the automatic entry and exit of floodwaters.
(D) Appurtenant structures. Structures accessory to a principal building may have the lowest floor below one foot above base flood elevation provided that the structure complies with the following requirements:
(1) The structure shall not be used for human habitation.
(2) The use of the structure must be limited to parking of vehicles or storage of items readily removable in the event of a flood warning.
(3) The floor area shall not exceed 864 square feet in R1, R1A, R4, and R6 zones.
(4) The structure shall have a low damage potential.
(5) The structure must be adequately anchored to prevent flotation, collapse, or other lateral movement.
(6) The structure shall be designed to automatically provide for the entry and exit of floodwaters for the purpose of equalizing hydrostatic forces. 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 net area of not less than one square inch for every one square foot of enclosed space;
(b) The bottom of all openings shall not be higher than one foot above grade; and
(c) Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they allow the automatic entry and exit of floodwaters.
(7) No utilities shall be installed except electrical fixtures in the structure, which must be elevated or floodproofed to one foot above base flood elevation.
(8) The structure shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters.
(9) If the structure is converted to another use, it must be brought into full compliance with the minimum standards governing such use.
(E) Manufactured homes.
(1) Require that all manufactured homes to be placed or substantially improved within the Floodplain Overlay District be elevated on a permanent foundation such that the lowest floor of the manufactured home utilities, mechanicals, and equipment, is one foot above the base flood elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of this article if the site meets the following criteria:
(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 as incurred substantial damage as the result of a flood.
(2) New manufactured home parks of five acres or 50 lots, whichever is less, shall follow the standards of § 25-19-24(H).
(3) All manufactured homes shall be anchored to resist flotation, collapse, or lateral movement. Manufactured homes must be anchored in accordance with local building codes or FEMA guidelines. In the event that over-the-top ties to ground anchors are used, the following specific requirements (or their equivalent) shall be met:
(a) Over-the-top ties be provided at each of the four corners of the manufactured home, with two additional ties per side at intermediate locations and manufactured homes less than 50 feet long requiring one additional tie per side;
(b) Frame ties be provided at each corner of the manufactured home with five additional ties per side at intermediate points and manufactured homes less than 50 feet long requiring four additional ties per side;
(c) Any additions to the manufactured home be similarly anchored.
(F) Existing structures.
(1) The provisions of this article do not require any changes or improvements to be made to lawfully existing structures. However, when an improvement is made to a structure in the floodplain, a floodplain development pennit is required and the following provisions shall apply.
(2) Any addition, alteration, reconstruction, or improvement of any kind to an existing structure where the costs of which would equal or exceed 50% of the pre-improvement market value shall constitute a substantial improvement and shall fully comply with the provisions of this article.
(3) Any addition, alteration, reconstruction, or improvement of any kind to an existing structure in the floodway shall comply with the provisions of § 25-19-22.
(4) Any addition, alteration, reconstruction, or improvement of any kind to an existing structure that will change the compliance requirements of the building shall require applicable documentation including an elevation certificate, floodproofing certificate, or no rise certification.
(Ord. 4293, passed 11-7-2022)