Wet Floodproofing

Measure under the Building Adaptation measures related to physical infrastructure opportunities to address flood risk

Looking for more? Head back to the Measures Explorer to check out other flood and seismic measures.


  1. Materials below base flood elevation (construction and finish) should be resistant to flood damage.
  2. Install raised platforms for valuable contents.
  3. Protect in place or relocate utilities.
  4. Re-grade surfaces, install pumps and sump pit to evacuate water after flood event.
  5. Flood openings to equalize hydrostatic pressure.
Wet floodproofing scheme on pier shed. ©Port of San Francisco


DESCRIPTION:
The space below the design flood elevation is constructed with flood-damage resistant materials in combination with flood vents to allow water to enter the structure and allow hydrostatic pressures to equalize. The enclosed space is built with flood damage resistant materials that do not need to be replaced if flooded, including pressure-treated plywood, concrete, and cement board. Flood vents are installed in the walls of the enclosure to let flood waters enter and leave by gravity, which allows forces on either side of the structure’s walls to equalize. This prevents the structure and foundation from collapsing in the event of a flood.



PHYSICAL INFRASTRUCTURE:
SHORELINE LOCATION:
Asset Specific




DESIGN LIFE:
ADAPTABILITY:
IMPACT ON THE WATERFRONT:
CONSTRUCTION COST:
N/A
N/A
Living with Water
TBD




COASTAL FLOOD HAZARDS MITIGATED:





Sea Level Rise
Storm Surge
Groundwater
Waves
Erosion




MEASURES COMPATIBILITY:
ECOSYSTEM SERVICES: Measure may affect these shoreline values
Flood
Seismic
All
All
Aquatic Habitat
Terrestrial Habitat
Water Quality
Carbon Storage




CONSIDERATIONS:

ADVANTAGES:

DISADVANTAGES:





  • Provides asset scale protection only.
  • Operations and maintenance obligations and costs must be considered in life cycle analysis.

  • Wet floodproofing is generally less expensive than dry flood-proofing.
  • Wet floodproofing, unlike dry floodproofing, does not rely on advanced planning or preparation.
  • Allows internal and external hydrostatic pressures to equalize, lessening the loads on walls and floors.

  • Extensive cleanup may be necessary if the structure becomes wet inside and possibly contaminated by sewage, chemicals, and other materials borne by floodwaters.
  • Pumping floodwaters out too soon after a flood may lead to structural damage.
  • Periodic maintenance may be required.
  • Does not minimize the potential damage from high-velocity flood flow and wave action.




CONSTRUCTION IMPACTS TO THE PUBLIC:

SEA LEVEL RISE ADAPTATION OPPORTUNITIES:

CASE STUDIES:





  • Site-specific construction closures would be required.

  • May be a supplement to other measures, limited effectiveness for long-term sea level rise.

  • New York City




DESIGN OPPORTUNITIES:





Ecological Enhancements

Urban Design

Form
  • N/A

  • N/A

  • N/A




INSTALLATION AND CONSTRUCTABILITY CONSIDERATIONS:

  • If the duration of the flood is longer than 1 day, wet floodproofing is not a reasonable approach to protecting a structure.
  • Flood vents must be engineered to comply with energy code requirements for the building envelope.
  • If basement utilities cannot be relocated to a higher level, they can be protected by being placed in a watertight room or enclosure made of impermeable material such as concrete.


OPERATION AND MAINTENANCE CONSIDERATIONS:

  • Wet floodproofed spaces require extensive cleaning and/or replacement of finishes following flooding, and may present exposure to sewage, chemical, or other hazardous materials in floodwaters.
  • Annual maintenance of wet proofing equipment is required to ensure proper performance.


Other Types of Building Adaptations:
Click the images and links below to explore other types of Building Adaptations.


Dry FloodproofingStructure Elevation



Head back to the Measures Explorer to check out other flood and seismic measures.


Measure under the Building Adaptation measures related to physical infrastructure opportunities to address flood risk

Looking for more? Head back to the Measures Explorer to check out other flood and seismic measures.


  1. Materials below base flood elevation (construction and finish) should be resistant to flood damage.
  2. Install raised platforms for valuable contents.
  3. Protect in place or relocate utilities.
  4. Re-grade surfaces, install pumps and sump pit to evacuate water after flood event.
  5. Flood openings to equalize hydrostatic pressure.
Wet floodproofing scheme on pier shed. ©Port of San Francisco


DESCRIPTION:
The space below the design flood elevation is constructed with flood-damage resistant materials in combination with flood vents to allow water to enter the structure and allow hydrostatic pressures to equalize. The enclosed space is built with flood damage resistant materials that do not need to be replaced if flooded, including pressure-treated plywood, concrete, and cement board. Flood vents are installed in the walls of the enclosure to let flood waters enter and leave by gravity, which allows forces on either side of the structure’s walls to equalize. This prevents the structure and foundation from collapsing in the event of a flood.



PHYSICAL INFRASTRUCTURE:
SHORELINE LOCATION:
Asset Specific




DESIGN LIFE:
ADAPTABILITY:
IMPACT ON THE WATERFRONT:
CONSTRUCTION COST:
N/A
N/A
Living with Water
TBD




COASTAL FLOOD HAZARDS MITIGATED:





Sea Level Rise
Storm Surge
Groundwater
Waves
Erosion




MEASURES COMPATIBILITY:
ECOSYSTEM SERVICES: Measure may affect these shoreline values
Flood
Seismic
All
All
Aquatic Habitat
Terrestrial Habitat
Water Quality
Carbon Storage




CONSIDERATIONS:

ADVANTAGES:

DISADVANTAGES:





  • Provides asset scale protection only.
  • Operations and maintenance obligations and costs must be considered in life cycle analysis.

  • Wet floodproofing is generally less expensive than dry flood-proofing.
  • Wet floodproofing, unlike dry floodproofing, does not rely on advanced planning or preparation.
  • Allows internal and external hydrostatic pressures to equalize, lessening the loads on walls and floors.

  • Extensive cleanup may be necessary if the structure becomes wet inside and possibly contaminated by sewage, chemicals, and other materials borne by floodwaters.
  • Pumping floodwaters out too soon after a flood may lead to structural damage.
  • Periodic maintenance may be required.
  • Does not minimize the potential damage from high-velocity flood flow and wave action.




CONSTRUCTION IMPACTS TO THE PUBLIC:

SEA LEVEL RISE ADAPTATION OPPORTUNITIES:

CASE STUDIES:





  • Site-specific construction closures would be required.

  • May be a supplement to other measures, limited effectiveness for long-term sea level rise.

  • New York City




DESIGN OPPORTUNITIES:





Ecological Enhancements

Urban Design

Form
  • N/A

  • N/A

  • N/A




INSTALLATION AND CONSTRUCTABILITY CONSIDERATIONS:

  • If the duration of the flood is longer than 1 day, wet floodproofing is not a reasonable approach to protecting a structure.
  • Flood vents must be engineered to comply with energy code requirements for the building envelope.
  • If basement utilities cannot be relocated to a higher level, they can be protected by being placed in a watertight room or enclosure made of impermeable material such as concrete.


OPERATION AND MAINTENANCE CONSIDERATIONS:

  • Wet floodproofed spaces require extensive cleaning and/or replacement of finishes following flooding, and may present exposure to sewage, chemical, or other hazardous materials in floodwaters.
  • Annual maintenance of wet proofing equipment is required to ensure proper performance.


Other Types of Building Adaptations:
Click the images and links below to explore other types of Building Adaptations.


Dry FloodproofingStructure Elevation



Head back to the Measures Explorer to check out other flood and seismic measures.


  • Thank you for learning about ways to strengthen the waterfront through the Measures Explorer! Please share your feedback on the Wet Floodproofing measure.

    Would you like to see it prioritized as a potential solution along San Francisco's waterfront? Do you have any concerns or input you would like to share about this measure?

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Page last updated: 04 September 2020, 13:21