Working with Zone A and Determining the Base Flood Elevation (2022)

Working with Zone A and Determining the Base Flood Elevation (1)Getting comfortable with using floodplain maps is an important part of participating in the National Flood Insurance Program (NFIP) and allowing residents in your community to purchase flood insurance. Maps can help you identify where it isn’t safe to build or where buildings need to be floodproofed. For instance, if a resident wants to build an accessory structure, you’ll need to use maps to help identify if it’s in a River Corridor (RC) and/or a Special Flood Hazard Area (SFHA) and how those designations influence the project.

Most floodplain maps were originally developed as part of the NFIP. There may be areas designated as floodplains that actually are at a much lower risk of flooding and may justify amending the maps with a Letter of Map Amendment (LOMA) through FEMA. Contact the FEMA Map Specialists for more information. And there may be areas that are indicated to be outside of the floodplain but actually could still flood. This certainly happenedduring Tropical Storm Irene. While not perfect, they’re still a solid guide for what areas are at risk of flooding and towns and cities need to use them to regulate building within the SFHA and the RC if a River Corridor bylaw has been adopted.

All RCs are mapped on the Flood Ready Atlas. Smaller streams with a watershed more than a half square mile will appear as yellow lines, for which the RC is officially fifty feet from the top of the stream bank. Learn more about River Corridors, how communities are reducing risk by protecting them, and how you might evaluate an application to build an accessory structure near one.

(Video) Base Flood Elevation - what it means and why you should care.

The mapping of SFHA is available on the same Atlas for about half of Vermont. NFIP paper maps were developed in the 1970’s to show SFHAs. FEMA has since created digital versions of some of these maps, including SFHAs for Bennington, Chittenden, Rutland, Washington, Windham and Windsor Counties and the communities of Bradford Village, Hardwick, Jay, Montgomery, Newbury, Stowe, and Wolcott. SFHAs will show up on the Flood Ready Atlas in these counties/communities.

What If Your Community Isn’t Digitized?

You’ll need to look to paper maps at your town offices or PDFs on the FEMA Flood Map Service Center site if your community isn’t on the list above. Keep in mind that you might have a separate map for the SFHA and for the Floodway, an area of high concern for any development. If a separate map exists for the Floodway, it will also be found in the FEMA Flood Map Service Center under All Products.

Working With Zone A

Working with Zone A and Determining the Base Flood Elevation (2)

There are multiple SFHA zones. You are very likely to run into Zone A floodplains. These do not have a determined Base Flood Elevation (BFE).

(Video) #Building in a #FloodZone #BFE + #PierAndBeam #Foundation

The BFE is the elevation (to the tenth of a foot) that has a 1% chance of flooding each year, or a 26% chance of flooding over the term of a thirty year mortgage. It’s an important number to know for determining where to elevate the lowest floor of a building, calculating flood insurance premiums, and determining if flood proofing is required.

Unfortunately, it’s not always easy to determine. Zone AE or Zones A1-30 do have a determined BFE, but you should still get a professional surveyor or engineer or documentation from a past study to identify exactly what the BFE is for a specific site.

Working with Zone A and Determining the Base Flood Elevation (3)For Zone A, get familiar with the NFIP Floodplain Management Requirements guide, starting on page 5-10. The following content is a summary from that section, but it’s best to feel comfortable with the details in order to keep your community safe. You can always call your Regional Floodplain Manager to discuss the details and get clarity on anything that isn’t making sense. Use them as your team to figure this out. It’s not easy and it’s important to get right because future permits and the physical safety and financial security of your neighbors may be based on the work you do.

Get the Base Flood Elevation for All New Development in Zone A

Any new development or substantial improvement within Zone A needs to have a BFE determined as part of the application process. To start, you’re required to look through what already exists. Here are all the possible places you’ll find data that could provide the BFE:

(Video) BFE Determination Tool

  1. Check the Flood Insurance Rate Maps (FIRM), Flood Insurance Study and municipal records, and check with your Regional Floodplain Manager regarding records and studies.
  2. Contact your Regional Floodplain Manager to see if FEMA, US Geological Survey, Army Corps of Engineers, National Resources Conservation Service, or Housing and Urban Development have conducted studies to determine BFE data for the site. The USGS may have also documented high water marks.
  3. If a body of water forms a boundary between two communities, the community on the other side may have a detailed study. Such base flood data are valid for both sides of a body of water.
  4. Existing State studies, including VTrans hydraulics studies for any nearby bridge or major culvert might provide BFE.
  5. Hydro-power dams likely have a study providing BFE for their federal license.

You could use data from any of these studies as long as they:

  • reasonably reflect flooding conditions expected during the base flood,
  • are not known to be technically incorrect, and
  • represent the best data available.

If the BFE Doesn’t Already Exist, Hire Someone to Determine It

If none of the sources above are able to provide the BFE, the next step is likely to require the property owner or developer to commision a study to determine it. This requires hiring a surveyor or engineer and provides information about the channel and local valley cross-sections, hydrology, and hydraulics. Detailed studies typically use modeling programs such as the US Army Corps of Engineers HEC-RAS. The people conducting this study should review FEMA’s document on Managing Floodplain Development in Approximate Zone A Areas.

Permit Documentation and the Importance of Doing This Well

Whichever method you use to determine the BFE, be sure to record on the permit records where the flood elevation came from and any helpful notes about how it was determined. This will help you be consistent with future development in the same area.

We want to stress the importance of developing an accurate determination for the safety of your community and anyone who purchases this building in the future. When Hurricane Harvey swept into Houston, TX in 2017, thousands of homeowners suffered significant damage because their homes were built in reservoirs that were designed to flood. They never knew they lived in a reservoir because local officials who signed the development permits either didn’t do their homework or based their determinations on other permits that omitted that information, as reported by the Texas Tribune, and later in the New York Times. Keep your community safe and help people understand their flood risk with the help of your Regional Floodplain Manager.

(Video) Flood Insurance 101: Base Flood Elevation Explained

Amending Zone A Maps

If you believe the SFHA is wrong, you can work with FEMA to consider amending the map and obtaining a Letter of Map Amendment (LOMA). You’ll need a surveyor or an engineer and you’ll want to start working with the FEMA map team and review Vermont’s guidance on the data for a LOMAin Zone A.

Get more information about maps

Working with Zone A and Determining the Base Flood Elevation (4)

Reflection Questions

  • Where are the Zone A flood hazard areas in your town or city?
  • What other map resources and other studies are on file in your town office?
  • Where are buildings with Letters of Map Amendment (LOMA) or recently constructed bridges that can help determine the BFE?
  • What other resources may be available to determine the BFE?

Working with Zone A and Determining the Base Flood Elevation (5)

(Video) How to use the FEMA flood map search


    What is Zone A? ›

    Zone A is the flood insurance rate zone that corresponds to the I-percent annual chance floodplains that are determined in the Flood Insurance Study by approximate methods of analysis. Because detailed hydraulic analyses are not performed for such areas, no Base Flood Elevations or depths are shown within this zone.

    What is Florida Flood Zone A? ›

    An Approximate Zone A is a special flood hazard area where BFE information is not provided. Areas subject to Coastal A Zone conditions (wave heights between 3 feet and 1.5 feet) may not be shown on FIRMs (see page 19).

    What is flood zone A in Louisiana? ›

    Zone A is the Special Flood Hazard Area (SFHA) and is a high-risk area. This area is subject to the 100 year flood or to a 1 percent or greater chance of flooding in any given year. No base flood information is provided. Base flood elevations (BFE) are determined for Zone AE.

    What is Zone A and Zone B? ›

    In India, there are two insurance zones – Zone A and Zone B. Zone A consists of eight cities including New Delhi, Mumbai, Kolkata, Chennai, Bengaluru, Hyderabad, Pune and Ahmedabad. Zone B comprises rest of India. Motor insurance premium is higher in the eight cities belonging to Zone A.

    What is the best flood zone? ›

    Flood zone X, also known as flood zone X500, is arguably the safest flood zone designation, as it's considered to be outside the 500-year floodplain and is also protected by a flood control system, such as a levee or dam, from the 100-year floodplain.

    Can you build in flood zone A in Florida? ›

    Flood-proofing is acceptable for non-residential buildings in AE and A Zones. Buildings must be flood-proofed a minimum of 2' above the BFE. Building Elevation compliance must be documented by submitting an Elevation Certificate (FEMA Form 81-31) at three stages during the construction process.

    How high do I have to build above the base flood elevation? ›

    Building codes require most new and Substantially Improved buildings be at a minimum height of BFE plus one-foot. Thus, a new or elevated building in an "AE-6" flood zone would need to be elevated elevated to a minimum of seven (7) feet above mean-sea-level.

    What is the lowest risk flood zone? ›

    The areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2-percent-annual-chance flood, are labeled Zone C or Zone X (unshaded).

    What is base flood elevation? ›

    The elevation of surface water resulting from a flood that has a 1% chance of equaling or exceeding that level in any given year. The BFE is shown on the Flood Insurance Rate Map (FIRM) for zones AE, AH, A1–A30, AR, AR/A, AR/AE, AR/A1– A30, AR/AH, AR/AO, V1–V30 and VE.

    What is an elevation certificate in Louisiana? ›

    An elevation certificate is used to determine the height of a building in relation to the Base Flood Elevation (BFE), the computed elevation to which floodwater is anticipated to rise during a specified storm or flood event.

    What is the average cost of flood insurance in Louisiana? ›

    The average price of NFIP flood insurance in Louisiana is $726 per year, though how much you'll pay may vary significantly based on the location of your home.

    What is Zone A in insurance? ›

    What Does Zone in Health Insurance Mean?
    Zone AZone BZone C
    Delhi/NCR, Mumbai including (including Navi Mumbai, Thane and Kalyan)Hyderabad, Secunderabad, Bangalore, Kolkata, Ahmedabad, Vadodara, Chennai, Pune and Surat.All Cities apart from A & B belong to Zone C
    8 Aug 2022

    What is the meaning of Zone B? ›

    B zone means areas between limits of the 100-year flood and 500-year flood; or certain areas subject to 100-year flooding with average depths less than one foot or where the contributing drainage area is less than one square mile. Sample 1Sample 2.

    Is USA Zone A or B? ›

    These items must be presented separately from items under 500g, and segregated by European Union, Rest of Europe, Rest of World Zone A (USA) and Rest of World Zone B.

    What does AE mean in a flood zone? ›

    AE zones are areas of inundation by the 1-percent- annual-chance flood, including areas with the 2-percent wave runup, elevation less than 3.0 feet above the ground, and areas with wave heights less than 3.0 feet. These areas are subdivided into elevation zones with BFEs assigned.

    What is a good flood factor? ›

    Properties more likely to flood at a greater depth have higher Flood Factors. Properties with less than 0.2% chance of flood water reaching the building footprint in every year analyzed are considered to have minimal risk or a Flood Factor of 1.

    What does flood zone 1 mean? ›

    Areas classified as Flood Zone 1 are those that have less than a 0.1% chance of flooding. A Flood Risk Assessment is mandatory for sites of 1 hectare or greater in Flood Zone 1.

    What are the flood zone codes in Florida? ›

    Flood Zone Definitions
    IN100-year floodplain, no BFEs determined.
    B, X500500-year floodplain (0.2% annual chance of flooding)
    C, XOutside 100-year and 500-year floodplain.
    D, UNDESPossible but undetermined flood hazards.
    9 more rows

    Does flood zone AE require flood insurance in Florida? ›

    Flood insurance in Florida's SFHAs

    In particular, AE flood zones or any zone designated by the letters A or V have a 1% chance of flooding annually. If you live in an AE zone and have a federally backed mortgage, you are required to purchase flood insurance.

    Why do developers build on flood plains? ›

    As there is growing pressure to find sites for housing, flood plain land is some of the cheapest available to developers. A flood plain is an area of flat land near a river, stream, lake or other open waterway that is subject to flooding when there is significant rainfall.

    Is higher or lower BFE better? ›

    The BFE is used to determine the risk of flooding for each structure in A- and V-zones by comparing the BFE to the elevation of the lowest floor of the structure. If the structure is elevated above the BFE, it has a low risk of flooding and will receive lower flood insurance rates.

    Where is the lowest floor elevation on an elevation certificate? ›

    On the Elevation Certificate, the top of the floor is certified as the lowest floor in A-zones and must be at or above the FPE. The bottom of lowest horizontal member supporting the floor system is certified in V- zones and must at or above the FPE.

    What is the lowest floor for rating? ›

    In a non-elevated building, the lowest floor used for rating is the building's lowest floor including a basement, if any.

    What is 0.2 chance flood hazard mean? ›

    Moderate flood hazard area, labeled Zone X, is the area between the limits of the base flood and the 0.2-percent-annual-chance (or 500-year) flood. The areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2-percent-annual-chance flood, are labeled Zone X.

    What does medium flood risk mean? ›

    Medium risk means that each year, there is a chance of flooding of between 1 in 100 (1%) and 1 in 30 (3.3%). Low risk means that each year, there is a chance of flooding of between 1 in 1000 (0.1%) and 1 in 100 (1%). Very low risk means that each year, there is a chance of flooding of less than 1 in 1000 (0.1%)

    What is a 500 year flood? ›

    The "500-year flood" corresponds to an AEP of 0.2-percent, which means a flood of that size or greater has a 0.2-percent chance (or 1 in 500 chance) of occurring in a given year.

    What countries are in Zone A? ›

    Zone A countries currently comprise Australia, Austria, Belgium, Canada, Czech Republic, Denmark, Finland, France, Germany (including pre-unification claims on East Germany), Greece, Hungary, Iceland, Ireland, Italy, Japan, South Korea, Luxembourg, Mexico, Netherlands, New Zealand, Norway, Poland, Portugal, Saudi ...

    How do I find out the zone of my area? ›

    How to find your property zone - YouTube

    What are Zones 1 and 2 in London? ›

    London is divided into 1–9 zones*, but most of it fits into zones 1–6. Central London is zone 1, zone 2 is the ring around zone 1, zone 3 is the ring around 2 and so on.

    How many zones are there in London? ›

    London is divided into 9 zones that start in its historic centre. Most top attractions are found in zone 1 and 2. Travellers will find Heathrow Airport in zone 6.

    Is USA Zone A or B? ›

    These items must be presented separately from items under 500g, and segregated by European Union, Rest of Europe, Rest of World Zone A (USA) and Rest of World Zone B.

    What are the 5 major time zones? ›

    For example, this United States time zone map shows the six designated time zones including Eastern, Central, Mountain, Pacific, Alaska, and Hawaii-Aleutian time zones.

    How are time zones determined? ›

    As Earth rotates on its axis, it moves about 15 degrees every 60 minutes. After 24 hours, it has completed a full rotation of 360 degrees. The scientists used this information to divide the planet into 24 sections or time zones. Each time zone is 15 degrees of longitude wide.

    What is a zone number? ›

    The zone number is required to start your parking session and identifies where you are parked. You can find the zone number located on signs and decals where the app is available.

    What is the meaning of zone number? ›

    1 a region, area, or section characterized by some distinctive feature or quality. 2 a sphere of thought, disagreement, argument, etc. 3 an area subject to a particular political, military, or government function, use, or jurisdiction.

    How do I find a zone on Google Earth? ›

    1. Open Google Earth.
    2. At the top, click Google Earth. Preferences.
    3. Click 3D View. Then, under "Show Lat/Long," choose a display format.
    4. Click OK. Coordinates will be displayed in the lower right corner.

    Where is Zone 2 based? ›

    Zone 2 is a British hip hop collective based in Peckham, London. The group has gained millions of views and streams through their music on YouTube and streaming platforms. The group is noteworthy for its rivalry with Moscow17.

    How do the zones work in London? ›

    The 'Zone' System Explained

    When it comes to getting around, London is divided into 'zones' 1-9, with 'Zone 1' being the city centre and 'Zone 9' being the outskirts of the city. The system itself exists as a method for TfL (Transport for London) to calculate a customer's travel distance and charge accordingly.

    How much does it cost from Zone 1 to 6? ›

    London Underground Fares 2022
    Zones TravelledSingle Journey TicketOyster / Contactless Payment Card~
    Zone 1 to 4£6.00£2.90
    Zone 1 to 5£6.00£3.20
    Zone 1 to 6£6.00£3.30
    Zone 2 to 6£6.00£3.30
    5 more rows

    Which is zone 1 in London? ›

    Zone 1 covers the West End, the Holborn district, Kensington, Paddington and the City of London, as well as Old Street, Angel, Pimlico, Tower Gateway, Aldgate East, Euston, Vauxhall, Elephant & Castle, Borough, London Bridge, Earl's Court, Marylebone, Edgware Road, Lambeth North and Waterloo.

    What zone is Buckingham Palace in London? ›

    Ticket office
    Ticket MachineAvailable
    Oyster topupUnavailable
    Oyster validatorAvailable
    Pre-purchase collectionAvailable
    Travel card zoneLondon Victoria is in Zone 1
    3 more rows

    What zone is Chelsea? ›

    While Chelsea doesn't have its own tube station, the closest stations are only a short walk from the area – these are Sloane Square on the District and Circle lines and South Kensington on the District, Circle and Piccadilly lines. Both are in Travelcard Zone 1.


    1. When Does A Land Surveyor Need To Calculate A Base Flood Elevation?
    (Redefined Horizons)
    2. Elevation Certificate BFE
    (Parkland College Land Surveying)
    3. What is my BFE? Base Flood Elevation: How It Affects You:
    (Robert Murphy)
    4. BFES1 - Introduction to BFE's
    (Joe Trimboli)
    5. Is Your Property In A Flood Zone? Find Out In 2 Minutes Or Less!
    6. Creating a flood map in InfoWorks ICM
    (Autodesk Innovyze)

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