The minimum NFIP requirement is to floodproof a building to the BFE. However, when it is rated for flood insurance, one foot is subtracted from the floodproofed elevation. Therefore, a building has to be floodproofed to one foot above the BFE to receive the same favorable insurance rates as a building elevated to BFE. Unit 9, Section B, discusses this is more detail.

NEW BUILDINGS IN V ZONES

Zones V1-30, VE and/or V identified on FIRMS designate high hazard areas along coastlines that are subject to high water levels and wave action from strong storms and hurricanes. The winds, waves and tidal surges associated with these storms cause water of high velocity to sweep over nearby land. Many V Zones are also subject to erosion and scour which can undercut building foundations.

ELEVATION ON PILES OR COLUMNS

All new construction and substantial improvements to buildings in V Zones must be elevated on pilings, posts, piers or columns. Elevation- on fill, solid walls or crawlspaces- and flood proofing are prohibited because these techniques present obstructions to wave action. The force of a breaking wave is so great that these types of foundations would be severely damaged, resulting in collapse of the building.

Construction on piles or columns allows waves to pass under the building without transmitting the full force of the waves to the building’s foundation. A special case is made for installing breakaway walls between the pilings or columns, but such walls are not supporting foundation walls.

While fill is not allowed for structural support for buildings with V Zones because of the severe erosion potential of such locations, limited fill is allowed for landscaping, local drainage needs, and to smooth out a site for an unreinforced concrete pad.

HOW HIGH? Within V Zones, the controlling elevation is the bottom of the lowest horizontal structural member of the lowest floor. (In comparison, within A Zones, the controlling elevation is the top of the lowest floor.) This is to keep the entire building above the anticipated breaking wave height of a base flood storm surge.

Posts of wood, steel, or pre-cast concrete are preferred over block columns and similar foundations that are less resistant to lateral forces. Pilings are preferred in areas subject to erosion and scour, but it is critical that they be embedded deep enough.

CERTIFICATION

A registered professional engineer or architect must develop or review the structural design, specifications and plans for the construction, and certify that the design and planned methods of construction are in accordance with accepted standards of practice for meeting the above provisions.

You must maintain a copy of the engineer’s or architect’s certification in the permit file for all structures built or substantially improved in the V Zone.

The North Carolina Division of Emergency Management has prepared a V Zone certification form to ensure that these requirements are met. Check with your state NFIP coordinator to see if your state has developed a V Zone certification form.

BREAKAWAY WALLS

Any walls below the lowest floor in a building in a V Zone should give way under wind and water loads without causing collapse, displacement or other damage to the elevated portion of the building or the supporting pilings or columns.

Any enclosed space below the lowest floor must be free of obstruction, or constructed with non- supporting breakaway materials such as open wood latticework or insect screening. Just as in A Zones, this space is to be used solely for parking of vehicles, building access or storage, and must be constructed of flood resistant material.