Missouri State Emergency Management Agency: Promoting Higher Standards with Freeboard Mapping

Solution

When the Missouri State Emergency Management Agency maps flood hazards for the state’s counties, in addition to federal regulatory Flood Insurance Rate Maps (FIRMs), they create maps showing the extent of flooding that is 1, 2, and 3 feet above the BFE.

Freeboard, or an additional amount of flooding above BFE, is a safety factor used in floodplain management. The Freeboard Maps developed by the state help to show where it rains it can flood. Using the information provided on these maps, communities can mitigate this risk in areas beyond the Special Flood Hazard Area, the mapped area of mandatory flood insurance purchase.

Communities can use the freeboard delineation on the map to determine the level to which a structure’s lowest floor should be elevated or floodproofed. By adopting these higher standards, communities can help reduce flood risk to development in, around, and beyond high-risk flood areas.

• Communities understand flooding can extend beyond the mapped Special Flood Hazard Area.
• Emergency managers know the places most likely to flood when the next large event occurs.
• Shows when a community adopts a stricter ordinance than the federal minimum standard.
• Communities can see the reduced risk associated with adopting a stricter ordinance.

Mapping and managing flood risk in areas beyond the 1%-annual-chance flood event improve public safety and reduce recovery costs after floods. It also decreases the potential for existing development to experience increased flood risk as upstream development occurs. The freeboard approach shows the impacts of increased risk.

A freeboard requirement adds height above the BFE to provide an extra margin of protection against unknown factors. Additionally, electrical, heating, ventilation, plumbing, air conditioning equipment, and other service facilities (including ductwork) must be elevated or waterproofed to the BFE plus freeboard. This reduces damage and reduces the need for Public Assistance, Individual Assistance, and Hazard Mitigation Grant Program funds.

Communities that adopt higher freeboard ordinances and participate in the National Flood Insurance Program’s Community Rating System can score points leading to reductions in flood insurance costs. Communities with freeboard ordinances may earn discounts of up to 45% on flood insurance policies. Including freeboard into a newly constructed residence adds from 0.25 to 1.5% to the total construction cost. This could mean adding $240 a year to a mortgage but saving more than a $1,000 a year on flood insurance for a building in a Zone AE riverine Many of the areas where Freeboard Maps were created had minimal increases in the horizontal area added to the floodplain because the 1%-annual-chance floodplain extends to the “bluffs”—places where the slope of the land rapidly increases.

Many of the areas where Freeboard Maps were created had minimal increases in the horizontal area added to the floodplain because the 1%-annual-chance floodplain extends to the “bluffs”—places where the slope of the land rapidly increases.
Many of the areas where Freeboard Maps were created had minimal increases in the horizontal area added to the floodplain because the 1%-annual-chance floodplain extends to the “bluffs”—places where the slope of the land rapidly increases.
These areas historically have lower claims on flood insurance as well.