Want to Flood-Proof a House? Make It Float.
When Hurricane Katrina hit in 2005, I was an associate professor at the Louisiana State University Hurricane Center in Baton Rouge, studying the aerodynamic behaviour of wind-borne debris. Because I used to live in New Orleans and knew the local landscape, several national reporters asked me to accompany them through the city streets after the storm to help them understand the context of what they were seeing. We launched off an elevated highway exit ramp and boated through roads that had become waterways. The damage that I saw that day brought me to tears—the city looked so eerie. We floated through the drive-through of a flooded McDonalds and picked up dogs that had been stranded by the flood. Afterwards, one of the reporters told me he’d seen a dead body floating in the water.
A few weeks later, I returned to New Orleans with researchers from the Hurricane Center to survey the wind damage. That’s when it became apparent that the flooding, not the wind, had caused the most devastating damage for residents. Wind damage was limited to a small set of buildings, but flooding had affected everybody and caused an estimated 1,600 deaths. In the city’s Ninth Ward, the flooding was so bad that electricity wasn’t restored to most of it for over a year. FEMA’s solution was for residents to elevate their houses or permanently relocate. I knew there had to be a better way. At that point, I had been a wind-effects engineering researcher for 25 years; after Katrina, I started researching the effects of water.
As the climate crisis intensifies, floods are becoming more frequent and severe. According to the United Nations, around two billion people will be at risk of extreme flooding by 2050. Last year, Hurricane Milton devastated parts of Florida, leaving behind an estimated $50 billion in damages. In September, Hurricane Helene wreaked havoc on much of the southeastern United States, with western North Carolina bearing the brunt of the damage. Over 230 people died and, weeks later, thousands in Asheville, North Carolina were still without power. Floods have become more intense here in Canada too. In July, 100 centimetres of rain fell on Toronto in mere hours, causing severe flooding across much of the city.
For hundreds of years, traditional communities in flood-prone regions have adapted their homes to float. In Thailand, people put bundles of bamboo under their houses and then tied the houses to trees, so they would be buoyant when the rains came without floating away. In Iraq, houses were built on piles of reeds, which would then become little islands when the land flooded. There were similar practices in Peru. Not all of these systems are ancient, but many are based on traditional knowledge, passed down through generations. I call these houses “amphibious” because they are adaptable to both dry land and water.
In a world of alarmingly frequent flooding, amphibious architecture can help us keep our homes intact, allowing water and buildings to co-exist. The secret is to modify existing houses to make them flood resilient. We can do this using a system with three key components: buoyancy elements, made of barrels or blocks of expanded polystyrene; vertical guidance posts that keep the buildings from drifting away; and structural steel subframes to connect it all. Altogether, the system is called a buoyant foundation. (I thought I’d come up with this myself, but then discovered that others were doing something quite similar, in places like Old River Landing near Baton Rouge, Louisiana.) It’s easier to modify houses that are small and light enough to lift, especially if they have a crawl space where the buoyant foundation can be installed. Here in Canada, cottages are prime opportunities for modification.
The cost to retrofit a building depends on the house’s location, size and construction. At Old River Landing, costs have been as low as US$5,000 for a 100-square-metre house, but they do the labour themselves and use as many inexpensive, recycled and cast-off materials as possible. In Canada, we need to consider things like freeze-thaw cycles and insulation requirements. Here, costs could be more like $70 per square foot, or approximately $700 per square metre. That is still less than the cost of extensive repairs, much less new construction.
During dry times, amphibious buildings look and function like regular buildings. But when waters rise, they transform into temporary boats, floating safely above the deluge and settling down as waters recede. It’s like giving your home an automatic life jacket. This approach isn’t just about protecting individual structures—it’s about preserving entire communities and their cultural heritage. In places where permanent elevation would alter the character of historic neighbourhoods, or where relocation isn’t feasible, amphibious architecture offers a way to maintain the status quo while increasing resilience.
In 2021, I got a grant to assess whether amphibious construction was appropriate for Canadian First Nations. Now, I’m working on an installation in Peguis First Nation in Manitoba, where I’ll be amphibiating a new modular home. The owner’s current home is mounded, meaning that it sits on a mound of dirt to avoid flood damage. But flooding in Peguis is expected to worsen due to the climate crisis and human manipulation of upstream water flow, so mounded homes are less flood resilient for that area. Once complete, his amphibious modular home will be an example of how First Nations and other Indigenous peoples in Canada can retrofit structures to make their land and homes more climate-resilient—without being displaced.
I’ve worked on several installations outside of Canada too. In Vietnam’s Mekong Delta, which is home to over 17 million people, flooding is integral to the environment: the soil carried by the flood waters replenishes the fertility of the land when nutrients have become too depleted to support crops. Flooding is also an important component of the local economy, which relies on rice farming. So traditional houses are built on stilts—but recently, floods are becoming more intense and unpredictable, so stilts are no longer enough.
In 2016, I received a grant to retrofit several houses in the Mekong Delta. After collaborating with locals and Canadian colleagues, I took several trips to Vietnam to retrofit four houses with buoyant foundations. A local carpenter and his assistants did the installation under my supervision. Then, to see how the foundations held up, I returned during the flooding season. When the annual floods arrived, all four houses floated. Once the flood waters receded, the houses returned to the ground, just as intended.
While I work mostly with retrofits, brand-new amphibious houses are also being built today. In the United Kingdom, architecture firm BACA constructed a new amphibious house on a small, flood-prone island on the Thames. This house is safe from floods up to 2.5 metres high, which is far above the anticipated flooding for the area. In the Dutch city of Maasbommel, one large lakeside development contains 32 new amphibious homes. These homes can withstand flood waters of up to 5.5 metres. They held up well during the flood that recently hit the city.
A lot of work still needs to be done to make amphibious architecture cheaper and easier to access. There are no building codes for this kind of structure anywhere in the world. Most of the time, when there is no building code for something, you won’t be allowed to build it. Last year, while working on a project in Quebec, I wrote up a preliminary set of guidelines that could eventually turn into an official building code for amphibious architecture in Canada. In the United States, FEMA has banned new construction of amphibious architecture for several reasons, including concerns about development in floodplains. While that’s a fair concern—we don’t want people building on unsafe land—this ban limits the options for people already living in flood-prone regions.
To me, the concept of amphibious architecture is simple: instead of resisting nature’s forces, we must adapt to them. In a future where water levels will be anything but predictable, amphibious architecture provides the flexibility needed to face whatever challenges may come—rising to the occasion, quite literally.
—As told to Caroline Bellamy
