Dry Floodproofing: Flood Adaptation Measure


Dry-floodproofing scheme on pier shed. ©Port of San Francisco

PHYSICAL INFRASTRUCTURE
SHORELINE LOCATION:
Asset Specific




DESIGN LIFE
ADAPTABILITY
IMPACT ON THE WATERFRONT
CONSTRUCTION COST
25+ Years
Low
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


DESCRIPTION:
A dry floodproofed structure is made watertight below the level that needs flood protection to prevent floodwaters from entering. Making the structure watertight requires sealing the walls with waterproof coatings, impermeable membranes, or a supplemental layer of masonry or concrete." Dry floodproofing includes:
  • Using waterproof membranes or other sealants to prevent water from entering the structure through the walls.
  • Installing watertight shields over windows and doors.
  • Installing measures to prevent sewer backup.


CONSIDERATIONS:
ADVANTAGES:
DISADVANTAGES:
  • Installation must be paired with a warning system to alert responsible parties of the need to install removable barriers.
  • The warning must be received far enough in advance to ensure sufficient time to install the measures.
  • May be more appropriate for commercial and institutional buildings.
  • Dryproofing is less costly than other retrofitting measures (e.g., elevating) but more expensive than wet floodproofing.
  • Does not require the additional land that may be needed for levees and seawalls.
  • May be fundable under FEMA mitigation grant programs
  • May not be used to bring a substantially damaged or substantially improved residential structures into compliance with the community's floodplain management ordinance or law.
  • Dry floodproofing requires human intervention and adequate warning to install protective measures.
  • Does not minimize the potential for damage from high-velocity flood flows and wave action.
  • Ongoing maintenance is required.
  • Flood shields may not be aesthetically pleasing.
  • May contribute to a false sense of security before and during storms.
  • May reduce the likelihood of residents to evacuate.


CONSTRUCTION IMPACTS TO THE PUBLIC:
SEA LEVEL RISE ADAPTATION OPPORTUNITIES:
CASE STUDIES:
  • Site-specific construction impacts are required for initial installation.
  • Deploying measures for tidal events would be disruptive for individual properties.
  • N/A
  • New York City


DESIGN OPPORTUNITIES:
Ecological Enhancements
Urban Design
Form
  • N/A
  • N/A
  • N/A


SITE-SPECIFIC CONSIDERATIONS:

  • Installation must be paired with a warming system to alert responsible parties of the need to install removable barriers. The warning must be received far enough in advance to ensure sufficient time to install the measures.
  • Based on the building code, may not be permitted for new structures. Not permitted in FEMA V zones.
  • May be more appropriate for commercial and institutional buildings.

INSTALLATION AND CONSTRUCTABILITY CONSIDERATIONS:

  • This form of floodproofing requires that the building be properly anchored to resist flotation, collapse, and lateral movement.
  • It also may require the reinforcement of walls to withstand flood forces and impact forces generated by floating debris.

OPERATIONS AND MAINTENANCE CONSIDERATIONS:

  • Property owners must have sufficient warning before a flood event to install all flood shields. They also must be in sufficient physical health to perform these activities before the flood waters arrive.
  • The dry floodproofing components must be inspected and maintained on a regular basis since the materials can deteriorate over time.
  • Owners should regularly inspect flood shields and closures to ensure a proper fit, and should check walls, floors, and floodproof coatings for cracks and potential leaks.


Download the Dry Floodproofing Factsheet.

Learn about other types of measures from our Measures Explorer page.


Dry-floodproofing scheme on pier shed. ©Port of San Francisco

PHYSICAL INFRASTRUCTURE
SHORELINE LOCATION:
Asset Specific




DESIGN LIFE
ADAPTABILITY
IMPACT ON THE WATERFRONT
CONSTRUCTION COST
25+ Years
Low
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


DESCRIPTION:
A dry floodproofed structure is made watertight below the level that needs flood protection to prevent floodwaters from entering. Making the structure watertight requires sealing the walls with waterproof coatings, impermeable membranes, or a supplemental layer of masonry or concrete." Dry floodproofing includes:
  • Using waterproof membranes or other sealants to prevent water from entering the structure through the walls.
  • Installing watertight shields over windows and doors.
  • Installing measures to prevent sewer backup.


CONSIDERATIONS:
ADVANTAGES:
DISADVANTAGES:
  • Installation must be paired with a warning system to alert responsible parties of the need to install removable barriers.
  • The warning must be received far enough in advance to ensure sufficient time to install the measures.
  • May be more appropriate for commercial and institutional buildings.
  • Dryproofing is less costly than other retrofitting measures (e.g., elevating) but more expensive than wet floodproofing.
  • Does not require the additional land that may be needed for levees and seawalls.
  • May be fundable under FEMA mitigation grant programs
  • May not be used to bring a substantially damaged or substantially improved residential structures into compliance with the community's floodplain management ordinance or law.
  • Dry floodproofing requires human intervention and adequate warning to install protective measures.
  • Does not minimize the potential for damage from high-velocity flood flows and wave action.
  • Ongoing maintenance is required.
  • Flood shields may not be aesthetically pleasing.
  • May contribute to a false sense of security before and during storms.
  • May reduce the likelihood of residents to evacuate.


CONSTRUCTION IMPACTS TO THE PUBLIC:
SEA LEVEL RISE ADAPTATION OPPORTUNITIES:
CASE STUDIES:
  • Site-specific construction impacts are required for initial installation.
  • Deploying measures for tidal events would be disruptive for individual properties.
  • N/A
  • New York City


DESIGN OPPORTUNITIES:
Ecological Enhancements
Urban Design
Form
  • N/A
  • N/A
  • N/A


SITE-SPECIFIC CONSIDERATIONS:

  • Installation must be paired with a warming system to alert responsible parties of the need to install removable barriers. The warning must be received far enough in advance to ensure sufficient time to install the measures.
  • Based on the building code, may not be permitted for new structures. Not permitted in FEMA V zones.
  • May be more appropriate for commercial and institutional buildings.

INSTALLATION AND CONSTRUCTABILITY CONSIDERATIONS:

  • This form of floodproofing requires that the building be properly anchored to resist flotation, collapse, and lateral movement.
  • It also may require the reinforcement of walls to withstand flood forces and impact forces generated by floating debris.

OPERATIONS AND MAINTENANCE CONSIDERATIONS:

  • Property owners must have sufficient warning before a flood event to install all flood shields. They also must be in sufficient physical health to perform these activities before the flood waters arrive.
  • The dry floodproofing components must be inspected and maintained on a regular basis since the materials can deteriorate over time.
  • Owners should regularly inspect flood shields and closures to ensure a proper fit, and should check walls, floors, and floodproof coatings for cracks and potential leaks.


Download the Dry Floodproofing Factsheet.

Learn about other types of measures from our Measures Explorer page.