Building a Home In Houston? Learn How To Read A FEMA Flood Map

Building a Home In Houston? Learn How To Read A FEMA Flood Map


If you are planning to build a new home or thinking of purchasing an existing home in a Houston flood plain, you need to do your research. Since the 1970’s the Federal Emergency Management Agency (FEMA) has been producing, storing, and updating flood maps for the National Flood Insurance Program for communities throughout the country.

Homeowners insurance does not cover flood damage. Flood Insurance Rate Maps, also known as FIRMs are the primary tool for state and local governments to mitigate the effects of flooding in their communities. These FIRMs also dictate the prices for Federal Flood Insurance for homeowners.

Let’s explore how to read and understand FIRMs, more commonly known as a FEMA flood map.


The National Flood Insurance Program was created by an act of Congress in 1968.The intent was to provide homeowners with protection from potential loss through an insurance program that allows those most in need to purchase affordable flood coverage.

FEMA produces Flood Insurance Rate Maps that outline areas at risk. The maps are created using historic data including hydrologic, meteorological and hydraulic data, as well as open space conditions, flood control systems and development.

A flood map provides a wide variety of information like:

  • Physical features like roads, highways, lakes, railroads, streams and other waterways
  • Special flood hazard areas (SFHA)
  • Base flood elevations (BFEs) or depths
  • Flood insurance risk zones
  • Areas subject to inundation by the 500-year flood

A flood map can help you to understand and identify SFHA areas, locate a specific property in relation to SFHAs, identify 100 and 500-year flood areas, identify flood magnitude in a specific area, locate regulatory floodways and identify undeveloped coastal areas where flood insurance is not available.

A flood map is used by a variety of people for several reasons. Private citizens, insurance agents, real estate brokers, community officials, lending institutions and Federal Agencies all use FEMA flood maps. Flood maps can be used to locate properties and corresponding flood insurance risk zones. Community officials use them to create and enforce Houston floodplain building restrictions, and lending institutions use them to determine whether flood insurance is required when making loans.


The two basic formats of a flood map are a flat fold flood map and a Z-fold flood map. Flood maps change all the time and as a result, the information they contain can vary. That being said, all flood maps share certain sections, basic elements, and symbols. They include:

  • Associated index map – Serves as a guide to the map sheets found on a flood map. Since the geographic area may be large, FEMA divides these sections into panels. The index is provided to indicate areas shown on the map.
  • Panel – Flood maps for communities may include one or more individual maps or panels. When a flood map contains multiple panels, that means the flood map for your community will not fit on a single page.
  • Title box – Contains the community name, panel number, date, and other information necessary.
  • Legend – Found on Z-fold maps, the Legend provides information on identifying risk zones and/or floodways on the flood map.
  • Standard symbols – There are seven standard symbols found on all flood maps. They include community name, community number, corporate limit or county line, insert notes, north arrow, panel limit line, and panel not printed notes.

In addition to these basic sections, there are fourteen additional elements that can be found on all flood maps panels regardless of type. These include:

  • Area not included – show areas in the panel area but not in the community covered
  • Base flood elevation
  • Coastal barrier area
  • Elevation reference marks
  • Floodplain Boundary – show 100 and 500-year floodplains
  • Hazard area designation – dark areas indicate greater flood risk
  • Map scale
  • Panel number
  • Notes to user – provides any additional information to clarify zones or special notes
  • River mile marker
  • Streamline
  • Zone designation
  • Zone division line – separates areas with different designations
  • Flood Insurance Risk Zone label – designate magnitude of hazard in specific communities

A FEMA flood map is a valuable resource when building or buying a home in an area prone to flooding. Understanding how to read it can help you to make informed decisions before making an investment into a piece of property or a community. Whenever you are purchasing or building a new property, do your due diligence and understand the real costs. Flood insurance can be expensive and understanding the risks involved, can help you to make the right decisions. If you have any questions about building a home in a flood zone, contact Houston Plans and Permits to discuss your project with one of our experts.

  • About Houston Plans and Permits
  • Houston Plans & Permits provides custom design services for builders and homeowners located in greater Houston. Our home plans are designed to meet your town’s building code requirements and our professional permit expeditors will oversee and complete your building permit applications and walk them through your town’s entire permit process.

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