Chapter 12D Flood Damage Prevention (part 2 of 2)

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. B.4. Crawlspace for Zones A1-30, A, and AE. 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 Page 12-D-14 Flood Damage Prevention hydrodynamic loads, crawlspace construction is not allowed in areas with flood velocities greater than 5 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 1 foot above the 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 1 square inch of flood opening is required per 1 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 2 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 4 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 Adopted 03/24/26 the interior elevation at or above the LAG. B.5. Manufactured Homes. 1. Require 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. For the purposes of this requirement, manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement. 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. Require that manufactured homes that are placed or substantially improved within Zones A1-30, AH, AE, V and VE on the community's FIRM 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; d. 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 to one foot above 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, AE, V and VE Zones, require that manufactured homes to be placed or substantially improved in an existing manufactured home park to be elevated so that. a. the lowest floor at one foot above the BFE; b. or the chassis is supported by reinforced piers no less than 36 inches in height above grade and securely anchored. B.6. Recreational Vehicles. Recreational Vehicle Standards Page 12-D-15 Flood Damage Prevention In A-1-30, AH, AO, AE, V and VE Zones, Recreational Vehicles, must either: 1. Be on the site for fewer than 180 consecutive days; 2. Be fully licensed and ready for highway use, on its wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached structures or addition, or 3. The recreational vehicle must meet all the requirements for ARTICLE IV, SECTION D PERMIT PROCEDURES, including the anchoring and elevation requirements of “manufactured homes” of this chapter. C. Standards for Subdivision Proposals. All proposals for the development of subdivisions including the placement of manufactured home parks and subdivisions shall meet Development Permit requirements of this chapter to minimize flood damage. 1. All subdivision preliminary plats/development plans shall include the mapped flood hazard zones from the effective FIRM. 2. BFE data shall be generated for subdivision proposals and other proposed development, including the placement of manufactured home parks and subdivisions, which is greater than 50 lots or 5 acres, or whichever is lesser. 3. All subdivision proposals including the placement of manufactured home parks and subdivisions shall have adequate drainage provided to reduce exposure to flood hazards. 4. All subdivision proposals including the placement of manufactured home parks and subdivisions shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize or eliminate flood damage. D. Standards for Areas of Shallow Flooding (Zone AO/AH) Located within the SFHAs established in Section 12-D.030 A. Lands to Which this Section Applies, are areas designated as shallow flooding. These areas have special flood hazards associated with base flood depths of 1 to 3 feet, where a clearly defined channel does not exist and where the path of flooding is unpredictable, and where Adopted 03/24/26 velocity flow may be evident. Such flooding is characterized by ponding or sheet flow; therefore, the following provisions apply: 1. All new construction and substantial improvements of residential structures have the lowest floor (including basement) elevated above the highest adjacent grade at least as high as the depth number specified in feet on the community's FIRM (at least 2 feet if no depth number is specified). If a BFE is given rather than a depth number, the lowest floor (including basement) shall be elevated above the BFE specified on the community’s FIRM. 2. All new construction and substantial improvements of non-residential structures: a. Have the lowest floor (including basement) elevated above the highest adjacent grade at least as high as the depth number specified in feet on the community's FIRM (at least 2 feet if no depth number is specified). If a BFE is given rather than a depth number, the lowest floor (including basement) shall be elevated above the BFE specified on the community’s FIRM; or b. Together with attendant utility and sanitary facilities be designed so that below the base flood elevation 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 of effects of buoyancy. 3. A registered professional engineer or architect shall submit a certification to the Floodplain Administrator that the standards of this chapter are satisfied. 4. Require within Zones AH or AO adequate drainage paths around structures on slopes, to guide flood waters around and away from proposed structures. E. Floodways (Zone AE) Floodways located within SFHAs are extremely hazardous areas due to the velocity of flood waters that carry debris, potential projectiles, and erosion potential, the following provisions shall apply: 1. Designate a regulatory floodway that will not increase the base flood elevation more than 1 foot. Page 12-D-16 Flood Damage Prevention 2. Encroachments are prohibited, including fill, new construction, substantial improvements and other development within the adopted regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase greater than 0.00 feet, unless higher standard option selected, in flood levels within the community during the occurrence of the base flood discharge. 3. All new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of Article V in this chapter. 4. Under the provisions of 44 CFR Chapter 1, Section 65.12, of the NFIP Regulations, a community may permit encroachments within the adopted regulatory floodway that would result in an increase in BFEs, provided that the community first applies for a conditional FIRM and floodway revision through FEMA. F. Coastal High Hazard Area (Zone V and/or VE) Coastal High Hazard Areas are SFHA established in Section 12-D.030 General Provisions A. Lands to Which This Section Applies, are areas that have special flood hazards associated with high velocity waters from storm surges or seismic activity and, therefore, all new construction and substantial improvements shall meet the following provisions in addition to the all provisions of Article V, Sections A, B and C: 1. Obtain the elevation (in relation to mean sea level) of the bottom of the lowest horizontal structural member of the lowest floor (excluding pilings and columns) of all new and substantially improved structures, and whether or not such structures contain a basement, and maintain a record of all such information. 2. Provide that all new construction and substantial improvements within Zones V1–30, VE, and V on the community's FIRM is located landward of the reach of mean high tide; 3. All new construction and substantial improvements shall be elevated so that the bottom of the lowest horizontal structural member of the lowest floor (excluding pilings or columns) is elevated to one foot above the base flood elevation. Adopted 03/24/26 Floodproofing shall not be utilized on any structures in Coastal High Hazard Areas to satisfy the regulatory flood protection elevation requirements. A registered professional engineer or architect shall develop or review the structural design, specifications and plans for the construction, and shall certify that the design and methods of construction to be used are in accordance with accepted standards of practice for meeting the provisions of Article V Section F. 4. All new construction and substantial improvements shall have the space below the bottom of the lowest horizontal structural member of the lowest floor either be free of obstruction or constructed with breakaway walls, open wood latticework or insect screening, provided they are not part of the structural support of the building and are designed so as to breakaway, under abnormally high tides or wave action without causing damage to the elevated portion of the building or supporting foundation system or otherwise jeopardizing the structural integrity of the building. The following design specifications shall be met: a. Breakaway walls shall meet the following design specifications: i. Design safe loading resistance shall be not less than 10 nor more than 20 pounds per square foot; or ii. Breakaway walls that exceed a design safe loading resistance of 20 pounds per square foot (either by design or when so required by State or local codes) shall be certified by a registered professional engineer or architect that the breakaway wall will collapse from a water load less than that which would occur during the base flood event, and the elevated portion of the building and supporting foundation system shall not be subject to collapse, displacement, or other structural damage due to the effects of wind and water loads acting simultaneously on all building components (structural and non- structural). The water loading values used shall be those Page 12-D-17 Flood Damage Prevention associated with the base flood. The wind loading values used shall be those required by the Utah State Building Code. b. All new construction and substantial improvements shall be securely anchored to pile or column foundations. All pilings and columns and the structure attached thereto shall be anchored to resist flotation, collapse, and lateral movement due to the effect of wind and water loads acting simultaneously on all building components. A registered professional engineer or architect shall develop or review the structural design, specifications and plans for the construction, and shall certify that the design and methods of construction to be used are in accordance with accepted standards of practice for meeting the provisions of Article V Section F. i. Water loading values used shall be those associated with the base flood plus one foot of freeboard. ii. Wind loading values used shall be those required by the current edition of the Utah State Building Code. 5. Prohibit the use of fill for structural support of buildings within Zones V1–30, VE, and V on the community's FIRM 6. Prohibit man-made alteration of sand dunes and mangrove stands within Zones V1–30, VE, and V on the community's FIRM which would increase potential flood damage. F.1. Elevated Buildings. Fully enclosed areas, of new construction and substantially improved structures, which are below the lowest floor or below the lowest horizontal structural member in V/VE zones shall meet all Article V Section: B.3 and: 1. Shall not be designed or used for human habitation, but shall only be used for parking of vehicles, building access, or limited storage of maintenance equipment used in connection with the premises. Access to the enclosed area shall be the minimum necessary to allow for parking of vehicles (garage door) or limited storage of maintenance equipment (standard exterior door), or entry to the living area (stairway or Adopted 03/24/26 elevator). The interior portion of such enclosed area shall not be finished or partitioned into separate rooms, except to enclose storage areas; 2. Shall be constructed entirely of flood resistant materials at least to the Regulatory Base Flood Elevation. Masonry or wood underpinning, regardless of structural status, is considered an enclosure and requires flood opening as outlined above. Page 12-D-18