Floodproofing

Installation of Temporary Flood Panels for Existing Structures

Note: All temporary installations of flood panels require a permit (PRFLP). Panel installations are only allowed on certain structures. 

Requirements for Single-Family Detached Residential

  1. The structure cannot be wood frame.
  1. Cannot be placed on any space currently using wet floodproofing as an approved mitigation measure. 
    1. For example cannot be placed on spaces with existing flood vents or breakaway walls like garages or downstairs enclosures.
  2. Cannot be in V or coastal A flood zones (see 2024 Collier County Coastal Flood Map | Collier County, FL).
  3. Flood panels can have a maximum height of three feet to resist a maximum of two feet of flood waters.
    1. Any panel over three feet in height will require signed & sealed drawings demonstrating with calculations how the structural wall and floor components can withstand hydrostatic and buoyancy uplift pressures for flood water heights greater than two feet.
  4. They cannot be part of; or be considered a substantial improvement.
  5. Manufacturers specifications must detail install methods and requirements, and clearly state the maximum hydrostatic pressures allowed.
  6. Some installations may require Concrete Masonry Unit cells be infilled prior to panel installation or other structural alterations.
  7.  All panel installations require a licensed Certified Residential Contractor, Certified Building Contractor, and/or Certified General Contractor for the installation.
  8. A floor plan is needed showing the location of each panel and a means of escape meeting the requirements of the Florida Building Code residential 2023.
  9. A signed notarized owners acknowledgement understanding the limitations and responsibilities of installing flood panels.
  10. There may be additional site-specific requirements that may also preclude the installation.

Requirements for Commercial or Mixed-Use Commercial-Residential Condos

For commercial or mixed-use commercial-residential condos see items listed below.

  1. Installation of flood panels must be able to meet substantially impermeable requirement specified at ASCE 24-14 (i.e. maximum accumulation of four inches water depth over a 24-hour period).
  2. Panels can only be applied to lobby/entrance/lower level- cannot be used for any residential part of building or portions of mixed-use with a residential unit or use.
  3. Would need signed & sealed drawings to include and provide egress(es) that meet all the requirements of FBC 2023 Chapter 10 at or above elevation Base Flood Elevation + one foot (Egress would likely be more than one door as number of egresses required per Chapter 10 is based on occupancy load).
  4. Need to document that velocity of floodwater adjacent to structure would be five feet per second or less.
  5. Any flood panels in lower level cannot impede safety/egress of residents in units above lobby.
  6. If located within Coastal A, any dry flood proof design needs to account for wave loads and potential for local scour/erosion.
  7. A signed notarized owners acknowledgement understanding the limitations and responsibilities of installing flood panels.
  8. For additional information see the (checklist link)

 

Flood Mitigation Methods for New Structures

All floodproofing mitigation measures require a permit (PRFLP)

Residential Occupancies:

Dry floodproofing as a mitigation measure is not allowed on any new residential construction. All residential construction must have the lowest horizontal member elevated at/or above Base Flood Elevation plus 12 inches.

Wet floodproofing is allowed on residential areas below flood when used for storage, parking or access only.

Commercial and Mixed Use Occupancies:

Commercial and Mixed Use Occupancies may utilize either dry floodproofing, wet flood proofing or a combination of the two.

Floodproofing Definitions - Dry vs. Wet

Dry Floodproofing

Dry Floodproofing 

Dry Floodproofing is defined as sealing a building to ensure that a building is watertight or impermeable to floodwaters. Normally, dry floodproofing is applied to building entrances, windows and equipment rooms located inside a building for protection from flooding. Flood panels are the most effective form of flood protection for interior spaces, equipment and the contents of a building. The use of dry floodproofing is required when constructing a new non-residential building or making substantial improvements (more than 50%) to an existing non-residential building located below the base flood elevation in an AE or AH Flood Zone. The rule also applies to mixed-use structures where the ground floor is identified as non-residential (used for retail or offices space and the second floor is living area). In accordance with FEMA guidelines, Dry Floodproofing is not permitted in Zone VE, V, V1-V30 flood zones. The following criteria are applicable to the design of the panels and the building walls: 

The structure, together with attendant utilities and sanitary facilities, is water tight to the flood-proofed design indicated on the certificate with walls that are substantially impermeable to the passage of water. This may include, back flow valves on all plumbing and sewer, water tight utility containers, sump pumps tied in to back up emergency power, sealants on walls

Additionally, all structural components must be capable of resisting the hydrostatic and hydrodynamic flood forces, including the effects of buoyancy and anticipated debris impact forces.  Non-residential structures located below the base flood elevation are required to show the use of flood panels on the plans when submitted to the building department. The panels must be constructed so that they protect the building one-foot (1 ft.) above the required base flood elevation. In addition, the owner of the building is required to store flood panels on site and submit a copy of a plan explaining the procedure for installing the panels and who will be responsible for installation. Failure to install flood panels before flooding occurs will nullify flood insurance coverage. For detailed information regarding design and installation of flood panels and dry floodproofing construction. Any person considering dry floodproofing should consult FEMA Technical Bulletin 3-93 Non-residential Floodproofing Requirements along with ASCE 24.

Both the floodproofing plan and installation must be certified by a Florida Licensed engineer

Wet Floodproofing

Wet Floodproofing

Wet Floodproofing is a design method that allows water to move in the enclosed parts of a home's lower area, such as the crawlspace or an unoccupied storage area, and then out when the water recedes. Materials and components used in these areas are selected for their ability to become wet, sustain minimal damage, dry, and be restored. 

The advantage of wet floodproofing is that, as floodwaters come into the prepared enclosed areas they will reach the same level as the outside water. This equalizes the water pressure on both the inner and outer walls and may prevent structural damage caused by unequal pressure on the structure's walls. All the materials below the flood protection elevation must be resistant to flood or water damage.

For detailed information regarding wet floodproofing design and construction, please consult FEMA Technical Bulletin 7-93 Wet Floodproofing Requirements, FEMA Technical Bulletin 1-08 Openings in Foundation Walls or ASCE 24.

 

 

Please consult a design professional for more information on the above-listed techniques. 

For additional information see the (checklist link below)

Floodproofing Documents

 

 

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