Collier County Government offices will be closed Monday, May 27, 2019, in observance of Memorial Day.

Building Within the Floodplain

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All development within the Special Flood Hazard Area (SFHA), including VE, AE, AH, and A flood zones are required to be reviewed by Collier County.   The following are general guidelines for building in the SFHA.  Contact Floodplain Management for more detailed information.

New Residential Structures in the SFHA
The most important step is to build a residence with the lowest living floor elevated above the Base Flood Elevation (BFE). This is a requirement of the Florida Building Code. The lowest living floor of a new home must also be 18 inches above the crown of the road if paved or 24 inches above the crown of the road if unpaved.  The crown of road requirements are standards established in the Collier County Flood Damage Prevention Ordinance. 
New Non-Residential (Accessory) Structures in the SFHA

Non-residential or accessory structures include detached garages and sheds and can be built with or without a concrete slab.  The following information should be taken into consideration when building an accessory structure.

An accessory structure with a concrete slab must meet both elevation requirements below:

  1. The elevation of the lowest floor must be at or higher than the crown of the road. 
  2. The lowest floor must be at or above the BFE OR if the lowest floor is below the BFE, all materials below BFE must be pressure treated or flood resistant materials and the structure must have flood vents. 

An accessory structure without a concrete slab must meet the following requirement:  

  1. The lowest floor must be at or above the BFE OR if the lowest floor is below the BFE, all materials below BFE must be pressure treated or flood resistant materials and the structure must have flood vents.
Substantial Improvement, Substantial Damage
The substantial improvement/substantial damage requirement (50% Rule) applies to any reconstruction, rehabilitation, addition, or other improvement of an existing structure.  The 50% Rule applies if the lowest living floor elevation is below the BFE AND the cost of the work equals or exceeds 50% of the market value of the structure before the start of construction.   An elevation certificate and/or 50% documents will be required to show compliance.
Retrofit an Existing Building with Flood Prevention Measures

There are a six major types of improvements that can be considered for an existing building that can help reduce or eliminate flood damage risks. They include:

  • Elevation
  • Relocation
  • Wet Floodproofing**
  • Dry Floodproofing**
  • Levees and Floodwalls
  • Demolition and Reconstruction

**Floodproofing techniques are approved for non-residential buildings and have specific requirements for their applicability.

More information on retrofitting can be found on the Information on Retrofitting Your Home document and in the FEMA Homeowners Guide to Retrofitting.

For assistance: Contact the Flood Information Hotline at (239)252-2942 or email

Page updated as of 04/23/18