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Orla Studios Guide to Flood Resilient Design and Architecture

The Big U – BIG Teams Vision for Rebuild by Design from BIG on Vimeo.
Designing for Flood Risk focuses on preparing buildings to withstand the threat of coastal flooding, while ensuring that they support everyday livability and quality of life. The devastation wrought in waterfront communities from recent Hurricanes and storm surge has brought a new level of urgency to this work. Flood tolerance is the capacity to remain undamaged and functional when flooded, which requires adapting the built environment to floods.

For a diagram of the Sea Level Rise impact to your community see maps below prepared by Union of Concerned Scientists: (all of  maps referenced here  are continuously being updated as new data comes in)

https://ucsusa.maps.arcgis.com/apps/MapSeries/index.html?appid=cf07ebe0a4c9439ab2e7e346656cb239

The USA National Oceanic and Atmospheric Administration:

https://coast.noaa.gov/slr/

or climatecentral.org:

https://choices.climatecentral.org/#12/40.7116/-74.0010?compare=temperatures&carbon-end-yr=2100&scenario-a=warming-4&scenario-b=warming-2

How can we ensure that buildings meet higher flood protection standards while preserving the vitality of our neighborhoods?

BASE FLOOD ELEVATION (BFE) the computed elevation in feet to which floodwater is anticipated to rise during the base flood, is the regulatory requirement for the elevation or floodproofing of structures. A building’s flood insurance premium is determined by the relationship between the BFE and a structure’s elevation.

“In the coastal velocity zone (“V zone”), where hurricane storm surge is the risk and wave action is the driving force, you need an open foundation on pilings, which allows waves to pass below the home’s occupied space. Waves pack an enormous punch—because water is so much more massive than air, a 2-foot or 3-foot wave is far more destructive than the hurricane winds that are pushing it. That’s why a 30-foot surge with high battering waves, like Hurricane Katrina brought in 2005, is able to scrape shorelines clean of buildings” Ted Cushman, Building mag.

We need to develop a flood-tolerant lifestyle based on flood adaptation at the property level:

 

Image result for modern architecture on stilts flood

Image result for modern architecture on stilts flood

Parday House near Wargrave: a completed home is raised up on a steel frame, above ground level

  • allows the site to flood, protecting  from potential damage
  •  flood water flows freely underneath the building- development does not adversely impact the flood plain as a whole and excess water isn’t pushed elsewhere

Beach House Landscape by Dirtwork NJ

 

Learning lessons from Hurricane Sandy in 2012,

  • critical wet-flood proofing measures were incorporated in the design to mitigate heavy flooding, property damage and disruption of vital services
  • The flood resilient landscape is built outside the sea wall to prevent soil erosion and to stabilize the natural shoreline
  • Native plants, establishing a dense network of root systems, surround the site to help the fragile dunes and create a sustainable, flexible approach to long-term maintenance
  • Bioswales are strategically planted to help prevent overwash from flowing directly back to the sea
  • They also trap stormwater runoff until it can be safely drained into the soil. Wood decking can temporarily capture runoff and maximize groundwater recharge, a defense against coastal subsidence
  • Rising 14 feet above sea level, the residence is accessed through a flood vent that allows for the equalization of pressure from unexpected and rapid surges and flooding

Image result for flood resilient design residential buildingImage result for combined dry and wet flood proofed ares building mixed use ny

RIBA competition entry above: flood solution

Permeable paving use in mitigating flash flooding caused by heavy rainfall:

Image resultImage result

  • permeable paving can drain into swales and retention ponds
  • reduces the risk of flash flooding by slowing down the flow of rainwater to help to discharge it back to the ground at a reduced flow rate

Drainage swales to prevent and ease flash flooding from heavy rainfall:

Image result for drainage swales

Swales can be part of an area’s natural landscaping, or they can be created to help ensure proper drainage, minimize runoff or capture storm water. In simple terms, they are generally shallow ditches that have gently sloping sides.

  • swales are a cost effective and more natural solution to traditional drainage construction
  • provide an opportunity to introduce more native species to a site
  • the swales can be  seeded with a mix containing species suitable for seasonally wet soils

Green corridors/temporary holding ponds for flood waters:

Water Boulevards,  a concept developed in England, creates a network of green corridors to manage and passively reduce flooding, integrating Green Infrastructure and Water Sensitive Urban Design into City streets. It can be applied as a network of green corridors to any city at risk of flooding. Water Boulevards is a project by Baharash Architecture.

Water Boulevards from Baharash on Vimeo.

Parks as water holding areas:

Parks can be designed to double as a water holding area during a flood event.  Parks, designed like this one in Copenhagen, allow recreational areas like skate parks to become temporary holding ponds for flood waters:

 

Image result for copenhagen flood park

Image result for copenhagen flood park

Image result for copenhagen flood park

Image result for copenhagen flood park

 
Mechanical and electrical equipment protection during flood events:
Image result for flood resilient design residential building
  • Mechanical and electrical equipment such as HVAC, boilers, and water heaters should also be relocated above BFE whenever possible. It is important not only to protect the equipment from flood damage, but also to prevent gas and oil from mixing with flood water contributing to other environmental risks.
  • In flood prone areas the main lines should be run through the ceiling or upper wall then down to switches and outlets set at mid-wall height. Any wiring installed below the BFE must be water-resistant

 

Two approaches to floodproofing buildings: Wet and Dry:

 

 Wet floodproofing:
  • allows buildings in the flood zone to be designed to allow floodwaters to enter and leave the structure without the use of any mechanical equipment.
  • Spaces that are below grade on all sides are prohibited, and the lowest occupiable floor is required to be elevated above the BFE
  • To prevent the collapse of building walls, a wet-floodproofed building allows for the equalization of hydrostatic forces on both sides of the wall during a flood event. This is achieved with openings at the ground level called flood vents see Orla Studios Guide to Flood Vents
  • All emergency exit stairwells and corridors shall be wet floodproofed and designed with hydrostatic openings (flood vents) to maintain the operation of the exit door. Emergency exits must open at grade. Evacuation points from elevated
    floors are not acceptable as emergency exits.

Related image

Dry floodproofing:

  • Dry floodproofing makes a structure watertight up to at least the level of the BFE through the implementation of sealants, flood shields, aquarium glass and strengthening structural components to resist hydrostatic forces from floodwaters, and protecting utilities from flood damage
  • Unlike wet floodproofing, the first floor of a dry-floodproofed structure can be at
    an elevation below grade or below the base flood elevation.
  • Through dry floodproofing, building access can be maintained at grade with no apparent differences from a non-floodproofed condition
  • Any of these conditions will generally entail higher construction
    costs. Dry floodproofing can present safety hazards during a flood event by blocking egress, so it is not allowed in entirely residential buildings
 
Image result for flood resilient design residential building
As a fairly common practice in New York City, new mixed-use buildings
in A zones have combined wet and dry floodproofed areas at the ground
floor. With this solution, portions of the building are sealed at the ground floor
to keep floodwaters out, while lobbies and entryways are designed to accommodate flooding
 
Image result for flood resilient design residential building
Image result for new york sea level rise

Flood and Hurricane proof skyscraper in NYC:

Image result for american copper building

Image result for american copper building

“In American Copper Apartments, (above)  developers decided to fortify the two towers with features that would mitigate the effects of a hurricane, including a flood resilient basement and lobby and a park that doubles as a bioswale.

Mechanical equipment that would typically be found in the basement — such as generators, electrical switchgear, and pumps — is on the second floor, above the flood line”  writes Lauren Young of Science Friday,

Image result for american copper building

Nearly 2 million people were left without power during the Sandy storm in NYC, and some were living in buildings for no power for a week, the developer of these apartments elected to put things like water pumps, elevators, lights, electrical charging outlets and people’s refrigerators on emergency power generators.

Full article about American Copper: https://www.sciencefriday.com/articles/building-flood-proof-skyscraper-resilient-climate-change/

Helping neighborhood vibrancy when first floors need to be elevated above base flood plain:

  • A planting buffer with shrubs or trees, combined with other façade treatments such as vertical articulation, can mitigate limited ground-floor activity
  • Architectural elements like turns in an entry stair, porches or decks for one and two family buildings can mitigate the distance between grade and the first occupied floor of a building, introduce an additional horizontal visual feature that gives the façade more of a pedestrian scale, and bring “eyes on the street” with a semi-private space closer to the sidewalk

Image result for modern flood elevated homes

Image result for modern flood elevated homes

Image result for modern flood elevated homes

  • Access elements such as stairs and ramps can be integrated into the landscaping to make a more seamless transition from sidewalk to building. Grading should be designed that does not create drainage problems for adjacent properties

Coastal community planning and development codes need to be updated immediately:

  • Planning and zoning could be modified allowing for additional flexibility to raise yards and building heights to resolve the difference between existing grade and BFE, making it possible to resolve the height differential between them

RESOURCES:

San Francisco has a Model for Grant Assistance for Flood Preparation:

The San Francisco Public Utilities Commission (SFPUC)’s Floodwater Grant Program (“Grant Program”) helps property owners in San Francisco minimize the risk of property damage due to flooding. They encourage Residents to take advantage of the Grant Program which reimburses flood victims who want to install improvements like doorway seals, flood gates or plumbing upgrades to lessen or prevent future flood damage. More info here:

https://sfwater.org/index.aspx?page=681

New Jersey Excellent Guide to Resilient Building Design:

http://www.hobokennj.gov/docs/communitydev/Resilient-Buildings-Design-Guidelines

For Cities trying to protect Utilities and Wastewater plants, excellent guide from US Environmental Protection Agency:

https://www.epa.gov/sites/production/files/2015-08/documents/flood_resilience_guide.pdf
New York Cities Video about their flood resilience strategies:

Orla Huq

#flood #floodplanning #floodvent #resilientarchitecture #greendesign #sustainable #resilientbuildings #flooddesign #retentionponds #flooding #wetproofing #dryproofing

Orla Huq Orla Studios Guide to Flood Resilient Design

Orla Studios Guide to Flood Vents

 

Image result for flood resilient modern architecture
Baca’s Flood Resilient Home, Oxfordshire, England
  • Protecting buildings that are constructed in special flood hazard areas (SFHAs) from damage caused by flood force is an important priority
  • The base flood is the flood that has a 1-percent chance of being equaled or exceeded in any given year (commonly called the “100-year” flood)
  • NFIP regulations require that residential buildings constructed in A zones like the Belvedere Lagoon in California have the lowest floor (including basement) elevated to or above the base flood elevation (BFE)
  • Enclosed areas (enclosures) are permitted under elevated
    buildings provided the enclosed areas meet certain use restrictions and construction requirements related to flood resistance, including use of flood damage-resistant materials and installation of openings to allow for automatic entry and exit of floodwaters: flood vents

Image result for flood vent diagram

  • If enclosure walls are not designed with openings to relieve the
    pressure of standing or slow-moving water against them (called
    hydrostatic loads), the walls can be damaged or fail during a
    flood
  • These openings allow floodwaters to reach equal levels on both sides
    of the walls, thereby lessening the potential for damage caused
    by a difference in hydrostatic loads on opposite sides of the
    walls
  • One type of flood vents is the smart vent which can be used for a home with a crawlspace or any enclosed area that desires both natural air ventilation and flood protection  http://www.smartvent.com  Clay Goodrich Contact. 

Image result for smart vent

  •  Flood Protection: The vent door is latched closed until it comes in contact with flood water. Entering flood water lifts the  internal floats which unlatch and allow the door to rotate open. This allows the flood water to automatically enter and exit through the frame opening, relieving the pressure from the foundation walls. Certified flood debris clearance is demonstrated with a 3” diameter opening when the flood door is activated
  •  Ventilation: A bimetal coil automatically opens and closes the ventilation louvers as temperature changes. No electricity is required. The louvers will be fully closed at 35F and fully open at 75F. In the event of a flood the internal floats lift to release the flood door to rotate open and relieve the hydrostatic pressure regardless of the louvers’ position, open or closed. Made of marine grade stainless steel they are perfect for salt water environmentsSMART VENT
  • openings are required in solid perimeter foundation walls that surround
    crawlspaces and openings are required in the walls of fully enclosed areas that meet the use limitations (parking of vehicles, building access, or storage). The requirement applies to new construction and to buildings that are undergoing substantial improvement, including repair of substantial damage

For a full guide to engineering the openings, height and required flood vent calculations consult this FEMA document

https://www.fema.gov/media-library-data/20130726-1502-20490-9949/fema_tb_1__1_.pdf

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