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Floodplain Development

If you have residential property that is located in a “Special Flood Hazard Area”, you should know that special requirements apply to any new construction or substantial improvements that you undertake. 

What is a Special Flood Hazard Area?

A Special Flood Hazard Area (SFHA) includes any area of Town that has a one percent chance or greater possibility of flooding in any given year. The one percent flood is also known as the 100 year flood.

How do I know if my property is located in an SFHA?

The Town’s SFHAs are depicted on the Town’s Flood Insurance Rate Maps which available for review at the Community Development Department and on-line at www.granit.unh.edu/dfirms/ and at http://msc.fema.gov/portal/search you can also search the Town GIS for your specific property at http://www.axisgis.com/WindhamNH/ (click on map layer and choose Flood map.

FEMA has recently up-dated its Flood Map Service Center (MSC) at www.msc.fema.gov/portal to provide easier access to flood hazard mapping information. The MSC web-based repository allows users to access the Flood Insurance Rate Maps (FIRMS) that determine floodplain boundaries and flood insurance regulations for the entire country, as well as flood risk data, Geographical Information System (GIS) datasets, and engineering reports.

What are the special requirements that apply?

The most significant requirement for new construction and substantial improvements of homes located in an SFHA is that the lowest floor of the structure must be constructed at or above the height of where the 100 year flood is expected to rise.

What about basements and crawlspaces?

If the home has a basement or crawlspace, the floor of the basement or crawlspace is considered the lowest floor of the structure and therefore must be constructed at or above the height of where the 100 year flood is expected to rise. The Town of Windham Zoning Ordinance and Land Use Regulations Section 607 covers floodplain development

What is a substantial improvement?

A “substantial improvement” is any improvement or repair to your home the cost of which equals or exceeds fifty percent of the home’s market value. This means that if you undertake a substantial improvement, you will need to raise the lowest floor of your home to or above the height of where the 100 year flood is expected to rise. 

Useful links:

  • www.floodsmart.gov/floodsmart/
  • http://www.nh.gov/oep/planning/programs/fmp/index.htm 

If you have questions about floodplain regulations contact Dick Gregory, ZBA Code Enforcement Administrator. For more information regarding floodplain building/construction regulations, contact Mike McGuire, Building Inspector.