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Building Commission
1 NW Martin Luther King Jr Blvd
Civic Center Complex, Room 310
Evansville, IN 47708
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  • Phone:  (812) 436-7871
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Building Protection Requirements

All buildings to be located in the Special Flood Hazard Areas are required to be protected from the flood damage below the Flood Protection Grade. New construction and substantial improvements must be constructed by methods and practices that minimize flood damage.

Building Protection Requirements Apply

  • Construction or placement of any building having a floor area greater than 400 square feet.
  • Structural alterations made to an existing building that has not previously been altered, the cost of which equals or exceeds 40 percent of the value of the pre-altered building (excluding the value of the land).
  • Reconstruction or repairs made to a damaged building where the costs of restoring the structure to its before-damaged condition equal or exceed 40 percent of the market value of the structure (excluding the value of the land) before damage occurred.
  • Installing a manufactured/mobile home on a new site or a new manufactured/mobile home on an existing site.
  • Installing a recreational vehicle on a site for more than 180 consecutive days.
  • Reconstruction or repairs made to a repetitive loss structure.

Building Protection Methods

Method 1 A residential or nonresidential building may be constructed on a permanent landfill.

  • The fill is placed in layers no greater than one foot deep before compacting to 95 percent of the maximum density obtainable with the Standard Proctor Test method.
  • The fill is extend at least 10 feet beyond the foundation of the building before sloping below the base flood elevation.
  • The fill is protected against erosion and scouring during flooding by vegetative cover, riprap, or bulk heading.
  • If vegetative cover is used, the slopes shall be no steeper than three horizontal to one vertical.
  • The fill does not adversely affect the flow of surface drainage from or onto neighboring properties.
  • The top of the lowest floor including basements is at or above the required Flood Protection Grade. 

Method 2  New construction or substantial improvements of elevated residential or nonresidential structures shall have the lowest floor at or above the Flood Protection Grade.

  • The building or improvements are required to be elevated on posts, piers, columns, extended walls, or other types of similar foundation, provided:
    • Walls of any enclosure below the elevated floor shall be designed to automatically equalize the hydrostatic flood forces on the walls by allowing for the entry and exit of floodwaters, through providing a minimum of two openings (in addition to doorways and windows) in a minimum of two exterior walls having a total net area of one square inch for every one square foot of enclosed floor area subject to flooding.
      • The bottom of all such openings shall be located entirely below the Base Flood Elevation and be no higher than one foot above the bottom of foundation grade (which must be equal in elevation to or higher than the exterior foundation grade).
      • Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwaters in both directions.
    • In no case may existing enclosures be designed or finished for occupancy or the area of the openings be reduced in size or ability to allow free flow of water through them.
    • Access to the enclosed area is required be the minimum necessary to allow for parking for vehicles (garage door) or limited storage of maintenance equipment used in connection with the premises (standard exterior door) or entry to the living area (stairway or elevator).
    • Any portion of a new building or improvement below the 100-year flood elevation is not enclosed in any manner which would impede the free flow of floodwaters (open lattice work or insect screening are permitted).
    • Where elevation requirements exceed six feet above the highest adjacent grade, a copy of the legally recorded deed restriction prohibiting the conversion of the area below the lowest floor to a use or dimension contrary to the structure’s originally approved design will be presented as a condition of issuance of the final certificate of occupancy.
  • The foundation and supporting members shall be anchored and aligned in relation to flood flows and adjoining structures so as to minimize exposure to known hydrodynamic forces such as current, waves, ice, and floating debris.
  • All areas below the Flood Protection Grade shall be constructed of material resistant to flood damage. The top of the lowest floor (including basement and garage) shall be located at or above the FPG
  • All electrical, heating, ventilation, plumbing, air conditioning equipment, utility meters, and other service facilities shall be located at or above the base flood elevation (BFE) plus one-tenth foot.
  • Water and sewer pipes, electrical and telephone lines, submersible pumps, and other waterproofed service facilities may be located below the base flood elevation (BFE) plus one-tenth foot.
  • New and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.
  • On-site waste disposal systems shall be located and constructed to avoid impairment to them or contamination from them during flooding.
  •  Any alteration, repair, reconstruction or improvements to a structure that is in compliance with the provisions of this chapter shall meet the requirements of “new construction”.
  • The interior portion of such enclosed area shall not be partitioned or finished into separate rooms.
  • The interior grade of such enclosed area shall be at an elevation at or higher than the exterior grade.

Method 3  Manufactured/mobile homes and travel trailers (also called recreational vehicles) to be installed or substantially improved on a site for more than 180 consecutive days must meet one of the following anchoring requirements:

  • The manufactured/mobile home shall be elevated on a permanent foundation such that the lowest floor shall be at or above the FPG and securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.
    • This requirement applies to all manufactured/mobile homes to be placed on a site:
      • Outside a manufactured/mobile home park or manufactured/mobile home subdivision.
      • In a new manufactured/mobile home park or manufactured/mobile home subdivision.
      • In an expansion to an existing manufactured/mobile home park or manufactured/mobile home subdivision.
      • In an existing manufactured/mobile home park or manufactured/mobile home subdivision on which a manufactured/mobile home has incurred substantial damage as a result of flood.
  • The manufactured/mobile home shall be so elevated so that the lowest floor of the manufactured/mobile home chassis is supported by reinforced piers or other foundation elements that are no less than 36 inches in height above grade and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.
    • This requirement applies to all manufactured/mobile homes to be placed on a site in an existing manufactured/mobile home park or subdivision that has not been substantially damaged by a flood.
  • Manufactured homes with fully enclosed areas formed by foundation and other exterior walls below the flood protection grade shall be designed to preclude finished living space and designed to allow for the entry and exit of floodwaters to automatically equalize hydrostatic flood forces on exterior walls as required for elevated structures.

Method 4  Recreational vehicles placed on a site shall either:

  • Be on the site for less than 180 consecutive days.
  • Be fully licensed and ready for highway use (defined as being on its wheels or jacking system, attached to the site only by quick-disconnect-type utilities and security devices, and having no permanently attached additions).
  • Meet the requirements for manufactured/mobile homes in subsection (B)(3) of this section.

Method 5  New construction or substantial improvement of any commercial, industrial, or nonresidential structure (or manufactured home) shall either have the lowest floor, including basement, elevated to or above the FPG (two feet above the base flood elevation) or be flood proofed to or above the FPG.

  • Should solid foundation perimeter walls be used to elevate a structure, openings sufficient to facilitate the unimpeded movements of floodwaters are required to be provided. 
  • Structures located in all A Zones may be flood proofed in lieu of being elevated if done in accordance with the following:
    • An Indiana-registered professional engineer shall certify that the building has been designed so that below the FPG the structure and attendant utility facilities are watertight and capable of resisting the effects of the regulatory flood.
      • The building design shall take into account flood velocities, duration, rate of rise, hydrostatic pressures, and impacts from debris or ice.
    • Flood proofing measures shall be operable without human intervention and without an outside source of electricity.