Flood-Resistant Buildings

Architects and engineers around the world are designing buildings that can handle rising water.

What’s at Stake

Rainfall events are becoming more extreme. With every one-degree F increase in temperature, the air can hold four percent more water. People in flooded areas of Tennessee and elsewhere due to Hurricane Ida experienced this first-hand. Rain falls in heavier bursts globally, as witnessed by this summer’s devastation in Europe. Many cities are unable to keep up with this type of flooding. For coastal homes, sea-level rise is part of the flooding problem. How can we design flood resilience into new buildings?

London Townhouses Sit Up Tall

The design firm DHaus won Dezeen magazine’s Future Urban Home competition in 2019 with their “Kentish Classic” townhouse design. Inspired by classic Georgian two-story homes, DHaus designed these colorful townhouses for heavy urban flooding in London. The townhouses are built from a prefab timber frame mounted on 3D-printed concrete platforms. The airy living spaces sit above the ground floor, out of harm’s way. The homes even incorporate green roofs, pleasant outdoor spaces that reduce stormwater runoff and moderate urban heat islands. See a video animation of the design here: 

Floating Houses and Climate Justice

  • Dhaka, Bangladesh: The LIFT (Low Income Flood-proof Technology) House was designed to create affordable flood-proof housing for low-income urban residents of Dhaka. Instead of resisting floods, the house floats up with rising water and sinks back down as the water recedes. The foundation is built of hollow ferrocement, bamboo, and about 8,000 reused plastic bottles. The house is tethered by a “service spine,” so it doesn’t travel during buoyant episodes. Read more about the LIFT House and see pictures here

  • New Orleans: The FLOAT House, similar to the LIFT House, is a low-income housing project designed to float during a flood. Designed by Morphosis Architects for the Ninth Ward, it sits on a raised base. In normal times, the base can be used as a porch. During floods, the house rises like a raft, secured by steel guideposts. The FLOAT House is green, using solar panels, rainwater collection, and geothermal heating and cooling. Read more about the FLOAT House and see pictures here

Flood-Proof Beach House

Studio Peek Ancona developed a handsome beach house for Stinson Beach, California, intended to resist storm surges and rising seas up to 12 feet high. It is built of a prefab metal unit set on concrete and steel columns, secured by a rebar-reinforced foundation. The ground floor garage is designed to detach from the foundation and float away during a flood, preventing it from stressing the house’s structural columns. The stairways are perpendicular to the ocean so water can flow through them during a storm surge. Read more here and here, and see architectural renderings here

Boston’s Flood Resilience Principles

The Boston Society of Architects commissioned an extensive 2013 report on how to build flood resilience into Boston homes and businesses.

  • “Wet flood-proofing” includes openings in the building (such as basement vents) to ensure that floodwaters enter and exit the home freely, preventing structural failure. This approach is best paired with sump pumps to clear the basement of water after a flood. 

  • “Dry flood-proofing” includes sealing the exterior walls and covering openings near or below grade (much as submarine bulkhead doors can be sealed). Even building doors can be sealed with exterior shields if it looks like a flood is imminent. 

  • Another recommendation in the report was to protect service equipment such as “HVAC, fuel systems, electrical systems, sewage management systems and drinking water systems” using barriers or by elevating these systems above ground level. Anchoring fuel tanks is also considered a best practice. Backflow valves can prevent sewer backups into basements. These measures prevent a “nightmare scenario” in which floodwaters enter people’s basements, spilling heating oil tanks and mixing the oil with sewage (p. 43). 

Lessons from Katrina: Spaulding Hospital

Spaulding Rehabilitation Hospital in Boston, seen from the water. Source: Jiaqian AirplaneFan, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Spaulding Rehabilitation Hospital was built in Boston following Hurricane Katrina. It sits on a neck of land at sea level, making it potentially vulnerable to storms. The hospital, which opened in 2013, is the first Boston building designed for projected sea-level rise, according to a report on healthcare climate resilience by the U.S. Department of Health & Human Services (p. 41). It is a highly flood-resistant structure, with a water-resistant membrane and many other design elements to protect it during high water events. 

I had the opportunity to tour the building in 2017 and was impressed by the practical design decisions. These included windows that could open for ventilation if heating or cooling were lost during a flood. The inability to open windows was a problem for hospitals in New Orleans during Hurricane Katrina (staff broke windows in desperation).

The HVAC and other critical systems were placed on the roof to keep the lights on even in extreme situations. Patient rooms were all located above the first floor, which was about 30 feet above the projected 500-year flood elevation. The building also used green roofs to moderate stormwater runoff during heavy rains.

None of these measures were mandated; they just made good business sense. The result was an attractive building with attractive views of the water. Spaulding Rehabilitation Hospital also saves its owners money because it uses about a third less energy than a conventional hospital the same size. 

Whether designing homes or businesses, flood resilience makes sense.