This article is provided for general informational purposes only and is not intended to provide individualized advice. Also talk with them about flood mitigation strategies or higher deductible options which can help lower their flood insurance premium. Be prepared to discuss what a negative elevation means. Negatively elevated structures are more likely to incur a loss because they are inundated more frequently, and the depths and durations of inundation are greater.īeyond the flooding risk, negative elevation will undoubtedly impact your client’s flood insurance premium. Identify whether the applicable local minimum flood risk reduction standard is more restrictive (i.e., larger) than the minimum FRRS. The lower below the Base Flood Elevation a building/property sits, the higher the flood risk. Determine best available base flood elevation (BFE) for the project location and the nearest long-term tide gauge with acceptable record length Add one foot to the BFE to determine the minimum FRRS elevation. Elevations are based on National Geodetic Vertical Datum. Negatively elevated buildings/properties are determined to be below the Base Flood Elevation. The height in feet that the 100-year flood is expected to rise above sea level. The higher above the Base Flood Elevation a building/property sits, the lower the risk of a flooding event. Positively elevated buildings/properties are determined to be above the Base Flood Elevation. Negative or positive elevation of a building/property refers to how that structure relates to the Base Flood Elevation. One of the biggest factors that could impact your clients’ flood risk is ‘Base Flood Elevation’ and how their buildings/properties relate to it.Īccording to the Federal Emergency Management Agency (FEMA), Base Flood Elevation is defined as “he elevation of surface water resulting from a flood that has a 1% chance of equaling or exceeding that level in any given year.” Have the design and method of construction certified by a registered architect or engineerĪlthough communities can still apply for a basement exception under 44 CFR 60.6(b), FEMA would have to prepare a special environmental clearance and make a determination that there would be severe hardship to the community if the exception were denied.Does ‘Negative Elevation’ Impact Flood Risk & Premium?įloods have an enormous impact on those who are affected taking lives, damaging property and buildings, disrupting school and work, and often requiring relocation and disaster relief.įEMA flood maps, such as the Flood Insurance Rate Map (FIRM), include at minimum, the Special Flood Hazard Areas (SFHAs), the Base Flood Elevations (BFEs) and the risk premium zones applicable to the community.Be constructed with adequate fill surrounding the building.Have the top of the floor of any basement area no lower than five feet below the elevation of the base flood.Floodproofed to at least one foot above the Base Flood Elevation (two feet if the elevation difference between the Base Flood and 500-year flood is greater than three feet).The community official should be contacted to identify partial community boundaries for the basement exception.Īn exception would be granted to a community contingent upon the community amending its floodplain management regulations to incorporate the requirements of 60.6(c)(2) in which the basements would have to be: ![]() The basement exception can be applicable to part of a community where the parameters of 60.6c are met.
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