Residential Floodplain Development Q&A

The 1% Annual Chance Floodplain is the area of land expected to be flooded should the large rain event having a 1% chance of occurring in a year based on historic rainfall data and modeling occur. In our community the 1% Annual Chance Floodplain (Floodplain) may also be known as the 100-year Floodplain, Base Floodplain, Special Flood Hazard Area (SFHA), and Zones A, AE, & AO.  In most areas in our community the Floodplain is comprised of two parts, the Floodway and the Floodway Fringe. The Floodway portion is at a minimum the channel that conveys the storm water runoff and additional area on either side of the channel. The Floodway Fringe is the remaining portion of the Floodplain.

Residential development within the Floodplain can occur if in compliance with federal and local regulations. However, development within the Floodway is more restrictive and is intended to remain open for safety of property from flood waters. Proposed residential development within the Floodway will need to demonstrate, through engineered modeling to show no rise in the floodwater elevations during the 1% Annual Chance rainfall event.

To find out if a property is in the Floodplain, contact the City of Huntsville Engineering Department at 256-427-5300 or view the maps through the City Interactive Mapping.

For regulations see Article 62 of the City of Huntsville Zoning Ordinance.

A primary structure (e.g. a home including its attached garage) is complaint with regulations if the finished floor and equipment servicing it (e.g. an HVAC unit) are elevated 1-foot above the Base Flood Elevation (BFE). If the structure is elevated on a crawl space, the crawlspace must meet flood venting requirements to include any duct work within the crawlspace.  An Elevation Certificate is required to determine if a structure is in compliance.

If a structure is non-compliant in the Floodplain, FEMA dictates a financial limitation on the amount of work (e.g. repair, renovation, etc.) that can be done to the structure before the structure is required to be made compliant.  This financial limitation is referred to as a Substantial Improvement. A Substantial Improvement is work (value of materials, labor, profit, etc.) that equals or exceeds 50% of the value of the structure not including the land value. In the absence of a current appraisal excluding land value, the Tax Assessor’s value can be used to determine the current value of the structure.

If a property owner has a mortgage/loan from a federally regulated or insured lender, the lender will require the property owner to purchase flood insurance if the structure is located within Floodplain. A lender can also choose to require flood insurance at their own discretion. The Property Owner may be required by the lender to provide an up-to-date Elevation Certificate of the structure. In some cases, the City of Huntsville Engineering Department may have one on file as a part of its regulatory authority; if not, then the property owner is required to provide an Elevation Certification from a Professionally Licensed Surveyor (PLS) or Engineer (PE).

Flood Insurance is provided by Federal Emergency Management Agency (FEMA) and is made available to property owners within the City through agents and insurers since the City of Huntsville participation in FEMA’s National Flood Insurance Program (NFIP). If your insurance agent does not sell flood insurance, you can contact the NFIP Referral Call Center at 1-800-427-4661 to request an agent referral.