Base Flood Elevation


Faisal Nadeem

In residential architecture, understanding the Base Flood Elevation (BFE) is crucial, especially when planning for the most efficient house design. The Preliminary Flood Insurance Rate Map (FIRM) helps in defining the elevation a potential flood might reach.

For instance, when constructing a maisonette apartment or managing 2 houses on one property, it’s essential to consider the Design Flood Elevation (DFE). The DFE uses the BFE to determine the appropriate elevation for construction of new structures within a flood zone.

The BFE indicates the elevation of surface water resulting from a flood with a 1% chance of equaling or exceeding a certain level in any given year.

This information is displayed on the Flood Insurance Rate Map (FIRM) for various zones such as AE, AH, A1–A30, AR, AR/A, AR/AE, AR/A1–A30, AR/AH, AR/AO, V1–V30, and VE. During a 100-year flood, the height the floodwaters are expected to reach is critical information for ensuring the safety and stability of buildings, affecting even the average bedroom size to ensure all living spaces are above the potential flood level.

What is a BFE?–Short Answer

The Base Flood Elevation (BFE) is the level that surface water will reach during a base flood. A base flood has a 1% chance of being equaled or exceeded in a given area each year.

What is base flood elevation?

The Base Flood Elevation (BFE) is a crucial measure for new construction, indicating the level that surface water will likely reach during a base flood. This type of flood has a 1% chance of being equaled or exceeded in any given year. The Federal Emergency Management Agency (FEMA) determines this value to help identify flooding risk in an area

Knowing the BFE is essential for design and construction, as it dictates the safe elevation for buildings. This level helps ensure that structures are built to withstand potential floods, considering the expected rise in water level. By using BFE, communities can better manage and mitigate flood risks, enhancing overall floodplain management.

Understanding BFE helps determine the necessary safety measures for structures, reducing the impact of flooding as water rises during such events.

BFE Meaning

When water levels rise to a high point during a 100-year flood, there’s a 1% chance of this happening in any given year. The Federal Emergency Management Agency (FEMA) creates maps to show these elevations for several flood zones. FEMA designates these zones as Special Flood Hazard Areas (SFHAs). Property owners in SFHAs need insurance if they have a federally-backed mortgage.

  • AE
  • AH
  • A1–A30
  • AR
  • AR/A
  • AR/AE
  • AR/A1– A30
  • AR/AH, AR/AO
  • V1–V30
  • VE

FEMA flood zones and base flood elevation—what do they entail?

The FEMA agency uses base flood elevation to classify areas at higher risk of flooding. They create color-coded maps to indicate whether a site is above the floodplain. Statistically, there’s a yearly chance of flooding in these zones: 500-year (0.2%) and 100-year.

Special Flood Hazard Areas (SFHA) have a significant risk, starting with codes like zone A99. The agency draws these maps to help homeowners understand the risk and take necessary precautions.

How can I find the base flood elevation number for my home’s location?

If you’re concerned about flooding, especially in low elevation areas or places near major bodies of water, checking your base flood elevation number is crucial. Start by consulting a FEMA flood map to identify your zone. Homes in zone A or zone V have a higher risk of severe flooding. The base flood elevation is marked as EL on the map, indicating how many feet the water would rise during a 100-year flood.

To find your home’s base flood elevation number, visit the FEMA Flood Map Service Center. By entering your address, latitude, and longitude, or your town and a nearby landmark, you can populate the map and identify your flood zone and its base flood elevation number. The number, rounded to the nearest foot, is an indication of the expected height of floodwaters.

It’s essential to have an elevation certificate to show the relation of your lowest floor to the benchmark BFE, especially if you’re in a high-risk area. Experts note that climate change is making floods more common, so even if your area doesn’t appear high-risk, you might still want to look into flood insurance. Get a quote from Kin to see how much you might pay for coverage.

Flood Insurance: Is Flood Insurance Required with a Base Flood Elevation?

If you live in an area with a Base Flood Elevation (BFE), understanding your flood risk is crucial. Properties in these zones face a significant risk of flooding, and the government-backed lenders may require flood insurance.

Federally regulated lenders like the Federal Housing Administration, Veteran Affairs, and the Department of Agriculture demand that you purchase a policy if your home is in a designated flood zone.

In my experience, maintaining flood insurance helps protect against natural disasters that are becoming more frequent due to climate change. Elevation certificates show how your property compares to the base flood elevations, which can impact your insurance rates.

Even a single inch of water can cause over $25,000 in damage to your property, so having a policy can save you from significant losses. Most policies are paid through an escrow account and are required to be maintained as long as you have a mortgage.

Tips for homes with a base flood elevation

  • Review regulations to see if you can elevate your home with fill, columns, or crawl spaces.
  • Make sure all usable spaces are above your BFE.
  • Landscape your property so the slope goes away from your house.
  • Raise all water-sensitive equipment above the base flood elevation.
  • Install a backflow valve to prevent water damage from sewer backup.
  • Clean rain spouts and keep them positioned so water moves away from your house.
  • Risk mitigation helps keep your insurance premiums from rising.

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

When the BFE is missing for your property, it requires hiring a surveyor or engineer. These people will conduct a study to determine the elevation. This typically involves gathering information about the channel and valley cross-sections, along with hydrology and hydraulics.

They might use modeling programs like HEC-RAS by the US Army Corps of Engineers. Reviewing FEMA’s document on Managing Floodplain Development is also essential. As an owner or developer, commissioning this process ensures accurate data for local areas.


What is base elevation?

Base elevation is the average height measured from at least three and up to eight points around the perimeter of a building. These points, located at the corners where the structure intersects the original topography, determine the minimum and maximum elevations.

What is another term for base flood?

The base flood elevation is also called the 1-percent annual chance flood. This term means there is a 1% chance of it occurring each year. It’s often known as the 100-year flood and is the recommended synonym for base flood elevation.

What is flood datum?

Understanding Base Flood Elevation starts with knowing what a datum is. It acts as the starting point for measuring and ensuring consistent elevations. For instance, predicting a flood to reach 100 feet above the ground relies on this reference to compare levels accurately.

What does base flood elevation determined mean?

The Base Flood Elevation (BFE) is a value set by the Federal Emergency Management Agency (FEMA). This agency helps to identify the flood risk in a specific area. By extension, it also determines the risk of a structure being impacted by flooding if the water level rises.