|Area of Special Flood Hazard
DEFINITION: Area of special flood hazard, commonly known as Special Flood Hazard Area (SFHA) is the land in the flood plain within a community subject to a 1 percent or greater chance of flooding in any given year. The area may be designated as Zone A on the Flood Hazard Boundary Map (FHBM). After detailed ratemaking has been completed in preparation for publication of the flood insurance rate map, Zone A usually is refined into Zones A, AO, AH, A1-30, AE, A99, AR, AR/A1-30, AR/AE, AR/AO, AR/AH, AR/A, VO, or V1-30, VE, or V. For purposes of these regulations, the term “special flood hazard area” is synonymous in meaning with the phrase “area of special flood hazard”.
IMPORTANT FACT: The SFHA on a Flood Hazard Boundary Map or FIRM is indicated with hash marks in a dark shared area.
DEFINITION: Base flood means the flood having a one percent chance of being equaled or exceeded in any given year.
IMPORTANT FACTS: Base flood is often referred to by the term “100 year flood.” This term is often misunderstood. “One percent annual chance flood” is more descriptive and accurate. A common misperception is that property located in the 100 year floodplain is at risk for flooding once every 100 years. Rather, in a 100 year floodplain there is a one percent chance of flood every year, equating to a 26 percent chance of flooding during the life of a 30 year mortgage. Everyone lives in a designated flood zone – any area has either a high, medium, or low risk of flooding.
The computed elevation to which flood water is anticipated to rise during a base flood is called the “base flood elevation.”
DEFINITION: Development means any man-made change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations or storage of equipment or materials.
IMPORTANT FACT: When reviewing local floodplain ordinances, be sure “development” is defined in a manner consistent with the NFIP definition in the CFR.
DEFINITION: Lowest Floor means the lowest floor of the lowest enclosed area (including basement). An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a basement area is not considered a building’s lowest floor; provided, that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirements of §60.3.
IMPORTANT FACT: An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a basement area is not considered a building’s lowest floor if certain conditions are met. The lowest floor is sometimes confused with finished floor or lowest habitable (finished or used as living or work area) floor. An unfinished floor may be considered the building’s “lowest floor” if the non-elevation design requirements are not met.
DEFINITION: Regulatory floodway means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height.
IMPORTANT FACT: A one foot rise is a standard for floodway surcharge amount. Many states have chosen to adopt a lesser surcharge amount (stricter standard). Always check to see how the floodway was computed in the state in which you are working.
DEFINITION: Substantial damage means damage of any origin sustained by a structure whereby the cost of restoring the structure to its before-damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.
IMPORTANT FACT: The provisions apply when a structure sustains damage/improvements of any origin and the cost of restoring the structure to its before-damage condition, and/or the cost of the improvements, would equal or exceed 50 percent of the market value of the structure before the damage/improvement occurred.
DEFINITION: Substantial improvement means any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure before the “start of construction” or the improvement. This term includes structures which have incurred substantial damage, regardless of the actual repair work performed.
IMPORTANT FACT: Substantial improvement does not include either any project for improvement of a structure correcting existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions OR, any alteration to a historic structure provided that the alteration will not preclude the structure’s continued designation as a historic structure.