Using a Flood Insurance Rate 
Map (FIRM) 
HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION FEMA 499/August 2005 Technical Fact Sheet No. 3 
Purpose: To explain the purpose of FIRMs, highlight features that are important to coastal builders, and 
explain how to obtain FIRMs. 
What Is a FIRM? 
• Flood hazards have been mapped by FEMA for 
approximately 20,000 communities in the United 
States, most commonly on FIRMs. A FIRM is a product 
of the Flood Insurance Study (FIS) for a community and 
is available in paper form and digital form. 
• FIRMs delineate Special Flood Hazard Areas (SFHAs) 
— land areas subject to inundation by a flood that has 
a 1-percent probability of being equaled or exceeded 
in any given year (hence, the terms “1-percent annual 
chance flood” and “100-year flood”). SFHAs are 
shaded on the FIRM and are divided into different flood 
hazard zones, depending on the nature and severity of 
the flood hazard.
Why Are FIRMs Important? 
• FIRMs show the limits of mapped flood hazard areas in 
a community. 
• The insurance zone designations shown on FIRMs are 
used in the determination of flood insurance rates and 
premiums. 
• The 100-year flood elevations and flood depths shown 
on FIRMs are the minimum regulatory elevations on 
which community floodplain management ordinances 
are based. 
• The information shown on FIRMs can affect the design 
and construction of new buildings, the improvement 
and repair of existing buildings, and additions to 
existing buildings (see Fact Sheet Nos. 2 and 29).
What Are Flood Hazard Zones and Base Flood 
Elevations, and How Do They Affect Coastal 
Buildings? 
• Base Flood Elevations (BFEs) are typically shown on 
FIRMs for flood hazard zones A and V. The BFE is the 
expected elevation of flood waters and wave effects 
during the 100-year flood (also known as the “Base 
Flood”). The BFE is referenced to the vertical datum 
shown on the FIRM. 
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insurance is required 
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insurance premiums 
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(see the sample FIRM on the next page) 
• 
j• j• j• X zones are areas that are not expected to 
flood during the 100-year flood. 
• 
• Older FIRMs label zones with a letter and 
• Older FIRMs label X zones as zone “B” 
designations the same. 
FIRMs Are Used By: 
Communities, to regulate new construction* 
e.g., foundation type, lowest floor elevation, 
use of enclosed areas below the lowest floorDesigners and builders, to ascertain flood 
hazards and plan new construction* 
Lenders, to determine whether flood 
Insurance agents, to establish flood 
Land surveyors and engineers, to complete 
National Flood Insurance Program NFIPelevation certificates see Fact Sheet No. 4Flood Hazard Zones In Coastal Areas 
V zones are those areas closest to the shoreline 
and subect to wave action, high-velocity flow, 
and erosion during the 100-year flood. 
A zones are areas subect to flooding during 
the 100-year flood, but where flood conditions 
are less severe than those in V zones. 
AO zones are areas subect to shallow 
flooding or sheet flow during the 100-year 
flood. If they appear on a coastal FIRM, they 
will most likely occur on the landward slopes 
of coastal dunes. Flood depths, rather than 
BFEs, are shown for AO zones. 
Newer FIRMs label zones as “VE” (V zone 
with BFE determined) and “AE” (A zone with 
BFE determined). 
number (e.g., A1, A10, V10). Ignore the 
number and look at the letter. 
or zone “C.” Treat the old and new zone 
FS No. 3 – Using a Flood Insurance Rate Map Home Builder’s Guide to Coastal Construction 08/05 Page 1 of 3 

• The BFE and flood hazard zone will affect the lowest floor elevation and foundation type for new 
construction* (see Fact Sheet Nos. 4 and 11). 
• Some communities have adopted higher standards for coastal construction (e.g., lowest floor elevations 
above the BFE, restrictions on foundation types and enclosures in A zones). Builders should consult their 
local jurisdiction for details. 
•Most communities have adopted the latest FIRM and FIS (and, therefore, the flood hazard zone and BFE 
designations) as part of their efforts to regulate new construction* in coastal floodplains. These communities 
will have adopted a floodplain management ordinance, which spells out the detailed requirements. 
* Note that “new construction” will include some additions, improvements, repairs, and reconstruction — 
consult the community about “substantial improvement” and “substantial damage” requirements. 
Sample FIRM 
This map is a portion of the FIRM for the barrier island community, Pensacola Beach, Florida. As shown 
below, several things are apparent from the map. 
FS No. 3 – Using a Flood Insurance Rate Map Home Builder’s Guide to Coastal Construction 08/05 Page 2 of 3 

Where Can I Get FIRMs and Other Information? 
The FIRM for a community, and the local floodplain management regulations, should be on file and 
available for viewing at the office of the community floodplain administrator. 
FEMA’s Map Service Center can be accessed at http://msc.fema.gov/MSC/. Index sheets and individual 
FIRM panels can be viewed on line through the MSC web site, and “FIRMettes” (user-selected portions of 
flood maps such as the sample above) can be created, saved, and printed. 
Is There Anything Else I Should Know About Coastal Flood Hazard Zones and Flood 
Elevations? 
• Many FIRMs are more than a few years old and may no longer accurately represent coastal flood hazards. 
Sections 7.8 and 7.9 of FEMA’s revised Coastal Construction Manual (FEMA-55, 2000) describe how coastal 
flood hazards are mapped and how to determine whether coastal FIRMs reflect present day flood hazards. 
• FIRMs do not incorporate the effects of long-term shoreline erosion. This information should be obtained 
from other sources (see Fact Sheet No. 7).
• Recent post-storm investigations and studies have shown flood forces and damage in coastal A zones 
can be very similar to those in V zones. Although FIRMs (and minimum NFIP building standards) don’t 
differentiate between A zones in coastal areas and riverine A zones, builders should consider adopting 
V-zone foundation and elevation standards for new construction in many coastal A zones. 
• Many communities and states require lowest floor elevations to be above the BFE. One term used to 
describe this higher elevation standard is Design Flood Elevation (DFE). 
• Many property owners have voluntarily constructed their buildings with the lowest floor several feet above 
the BFE in recognition that the flood elevation in some storms will exceed the BFE. 
FEMA 
PO Box 1038 
(800) 358-9616 
Copies of FIRMs, FISs, and related products can also be obtained from FEMA for a nominal fee. 
Contact FEMA’s Map Service Center at: 
Map Service Center (MSC) 
Jessup, MD 20794-1038 
FS No. 3 – Using a Flood Insurance Rate Map Home Builder’s Guide to Coastal Construction 08/05 Page 3 of 3