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Worried About Living in a Flood Zone? Try a House That Floats.

By Ronda Kayson
The New York Times
2023.September.29

Eventually, coastal cities threatened with rising tides and bigger storms could use not just the waterfront, but also the water, as places to build housing.

As sea levels rise, developers are eyeing the water as the next frontier, potentially mooring yachts shaped like floating homes in Biscayne Bay in Miami, like in this photo.Credit…Arkup

As sea levels rise and storms worsen, threatening the planet’s fragile coastlines, some architects and developers are looking to the water not as a looming threat, but as a frontier for development.

“We want to change cities worldwide, we want to see how we can push the cities into the water,” said Koen Olthuis, a Dutch architect and the founder of Waterstudio, an architectural firm that specializes in floating buildings. “I hope that in 50 years time, we look back at our cities and say, ‘Well, floating structures, they are just part of this city recipe, they make sense, they add something to it, they bring us space, cheap houses, flexible cities.’”

About 3 billion people, roughly half of the world’s population, lives within 125 miles of a coastline, according to the Population Reference Bureau. Eventually, coastal cities could claim not just the waterfront, but also the water, building in their harbors, bays, canals and rivers.

It’s already happening in the Netherlands. With a third of its land below sea level, the country has floating offices, a floating dairy farm and a floating pavilion. Floating buildings are often built atop concrete and foam pontoon foundations, allowing them to sit on the water, and rise and fall with currents.

Proponents of the design argue that these buildings protect the environment. While a 2022 study published in the Journal of Water & Climate Change found that floating structures can have a positive benefit, attracting birds to nest and providing habitat and food for sea life, the study also found that they can impact light, currents, wind patterns and water quality. .

A short ferry ride from central Amsterdam is Schoonschip, a community of 30 floating houses, half of them duplexes, on a canal in a former manufacturing neighborhood. The homes, made of wood, are built atop concrete bases and connected by a jetty.

The first residents arrived in 2019, more than a decade after the neighborhood was first conceived. Maarten Remmers, 43, a film producer, paid 450,000 euros for the three-story, three-bedroom home he lives in with his girlfriend and their two children. The house feels steadier than a boat, but sways with the currents. “If it storms, you really feel it, and you see the land dancing,” he said.

The community of more than 100 people feels like a village, with shared e-bikes and cars, and a floating garden. His children, ages 7 and 9, fish and swim in the canal. “You wake up with birds, and ducks next to your window, or swans,” he said.

While Mr. Remmers looks at his community as a sustainable one — the homes have heat pumps, green roofs and are solar powered — he does not see moving his family onto the water as a solution to rising sea levels, balking at the argument that floating cities are somehow a solution to climate change. “It’s nonsense,” he said. “If the whole city is flooded, then, OK, our house will float, but there’s no reason to keep living there anymore.”

A rendering of brightly colored apartment buildings floating on water. — The Maldives, a country vulnerable to rising seas, is building a floating neighborhood near its capital, with apartments, schools, shops and restaurants, as shown in this rendering.Credit…Dutch Docklands Maldives and Waterstudio

Yet, as sea levels rise, low-lying countries like the Maldives are grappling with an existential threat, and building on the water is a way to create land from the encroaching sea. The government, in partnership with the developer Dutch Docklands, is building an entire floating neighborhood in a lagoon 10 minutes by boat from Malé, the nation’s capital.

Next year, the first phase of the 5,000-modular unit development will open — apartments, schools, shops and restaurants built on a floating landscape of serpentine jetties fitted together like Lego pieces. “That is the future,” said Mr. Olthuis, the Dutch architect, who developed the master plan for the Maldives development.

But there are bureaucratic barriers. City building and zoning codes do not address floating houses and neighborhoods built on concrete and foam foundations. Even Amsterdam, a city of known for its houseboats, was not ready for a waterborne neighborhood like Schoonschip, and it took years to navigate the bureaucracy. “There were lots of times I was totally fed up with all the legislation,” Mr. Remmers, who was involved in the development of the community, said. “It took so long.”

Cities may not be prepared for floating neighborhoods, but they are familiar with yachts. So Nicolas Derouin and Arnaud Luguet, two French engineers, designed a yacht that looked like a condo, with a flat roof and open-concept floor plan. Lower the retractable hydraulic pilings down to the ocean floor, and the boat stabilizes. In a storm, the pilings and jack-up system can lift the boat out of the water, protecting it from a storm surge. In 2019, they built their first model — the Arkup 75 — selling it for over $4 million. (The owner is living on the 75-foot boat offshore from the mansion he is building in Miami, Mr. Derouin said.)

Now Arkup has a dozen orders placed for a smaller version, the Arkup 40, which sells for between $500,000 and $1.2 million, depending on configurations. The boats, with 660 square feet of indoor living space, and more than twice as much outdoor space, are being built in Indiana and will travel to Miami by truck.

Dock one outside a beach house and it acts as the ocean’s answer to a pool house. “It becomes an extension of their waterfront property, like a guesthouse or a family room,” Mr. Derouin said. Moor it far from shore and it is an isolated retreat. Lower the pilings and open the retractable decks of the Arkup 40 alongside another one, and you create a network of vessels far from land where you can walk from one boat to the other. “You create a floating villa,” Mr. Derouin said. “You can really create a floating community.”

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Afloat in the Flood Zone

The New York Times, Peter Edinin

ROM Jakarta to the coast of Louisiana, floodwaters are a growing concern. This is especially true in delta regions, where river and sea combine, as they do in many of the world’s great cities, to create a double hazard.

No place is more concerned with this problem than the Netherlands, literally “the lowlands,” where for centuries people have lived on the edge of water-borne disaster. About a quarter of the country is land reclaimed from the sea, while half of it lies at or below sea level. The country’s vulnerability to rising water levels, commonly ascribed to climate change, was on full display last summer at the Rotterdam Architecture Biennale, titled “The Flood,” which contained proposals for a floating soccer stadium and housing built on spongelike synthetic riverbanks capable of absorbing flood waters.

“Since World War II, the Dutch have relied on technology for protection from the rivers and the sea,” said Adriaan Geuze, a landscape architect and the chief curator of the biennale. “We are convinced that this is not a clever way to deal with reality, and three months after the exhibition closed, Katrina showed us the truth of that.”

For the Dutch, as for everyone else, there appear to be no simple solutions, only costly ones, like abandoning vulnerable terrain. For the first time in its long history, the Netherlands has begun to strategically uncreate itself; last year the government, at the start of a 15-year program, began buying up land and reserving it as flood plain, mostly along river banks. The Dutch are also exploring a solution as old as the first flood: floating architecture. The notion is still in its early stages, with only a handful of houses built and a few developments under way, but it has already attracted the attention of leading Dutch designers and some developers.

If it proves sufficiently functional, affordable and attractive, floating architecture could find its way to many of the world’s flood zones.

In the town of Aalsmeer, in the southwest, an area badly damaged by floods in 1953, Sjef Snel and his wife, Agnes, moved into their floating house a little more than a year ago. “It took me over six months to settle down,” Mr. Snel said, “and then I knew I was at the right place.”

Even better, Mr. Snel, 45, says he has no more concerns about flooding. “I feel totally safe,” he said. “Our living room is eight inches above water and the house is mobile. There is certainly no reason to be fearful.”

The house was designed by Agnes Snel in collaboration with Koen Olthuis, a 34-year-old Dutch architect who has emerged as a leading advocate for floating buildings. His small practice, called Waterstudio, is devoted exclusively to such projects. “Most of these projects are in the first phase,” Mr. Olthuis said from his offices in Rijswijk, “since using water, not just defending against it, is a new idea.”

Dura Vermeer, one of the country’s largest builders, is also experimenting with floating structures. It has created a community of 48 amphibious homes in Maasbommel, on the banks of the Maas river. The brightly colored 700-square-foot homes, designed by Factor Architecten, a large design firm based in Amsterdam, are set in what was once a parking area for recreational vehicles. “These are not houseboats,” said Ger Kengen of Factor. “You have to design everything as if it were on the ground, only 10 feet up in the air.”

Anna van der Molen, 45, who lives with her husband and child in one of the houses, said “not only do we live on water, but we also live with water.” The houses sit on concrete pontoons that rest on footings projected slightly above the river bottom at low water periods, but ride up during floods along a pair of 15-foot poles. Their low center of gravity, created by the weight of the pontoons, makes them very stable. Still, Ms. van der Molen said, “Sometimes it is scary, very scary, when the water is coming up.”

Chris Zevenbergen, the director for business development of Dura Vermeer, said, “We decided five years ago to take water as one of our strategic objectives. The company is also designing a “floating city,” for 12,000 people near Schiphol Airport, not far from Amsterdam, in the fastest growing area of the country. The design will cost more than $1.2 million, 45 percent of which will be paid for by the government. The goal is a town that can live with flooding, not just wall it off, using a variety of floating structures and an extensive system for rainwater storage, among other means. The challenge is aesthetic as well as commercial, notes Herman Hertzberger, who at 73 is regarded by many as the grand old man of Dutch architecture. No one yet knows what waterborne housing should look like, he said, or how it should function. Mr. Hertzberger offered some possibilities several years ago in the design of an amphibious house that revolves on a base of massive steel pontoons, turning the house, “toward the sun or away from a neighbor,” he said. The house is in Middelburg, the capital of Zeeland, the area hardest hit by the 1953 flood, which killed more than 1,800 people.

The prototype, now owned by Don Monfils, an architect, and his wife, Lidia Filius, brought a commission from a Dutch builder to create two clusters of floating houses, each set on long concrete foundations, in the same area. There will be about 20 houses in all, Mr. Hertzberger said.

But it remains to be seen how waterborne homes, as a form, will evolve.

“The problem I have is that I have not seen any great examples of contemporary floating architecture,” said Aaron Betsky, director of the Netherlands Architecture Institute in Rotterdam. “What makes a floating house different than a houseboat?”

Giving land back to the river and the sea is a solution that will create its own problems. The Netherlands is small and among the world’s most densely populated countries, so the lands set aside for water must be put to productive use.

Bart Mispelblom Beyer, a principal with Tangram, a well-known Dutch architectural office, said his firm has designed 85 houses for a tidal zone near the southern city of Dordrecht. The buildings, which will rise and fall with the tide, are being built on tidal lands because that was the only site for new homes the developer could find.

A few months ago, the Ministry of Housing, Spatial Planning and the Environment announced that it was accepting proposals to develop amphibious and other types of flood-resilient structures in 15 flood-prone areas. These are places, like the plains between rivers and the dikes that hold back their waters, in which the Dutch have never permitted construction.

Some architects remain skeptical about the large-scale feasibility of floating homes. Art Zaaijer designed six houses for a lakeside development at IJburg, outside Amsterdam. They are amphibious, and since they sit in a nature preserve, are designed to be nonpolluting.

Unfortunately, Mr. Zaaijer said, development has been stalled by an economic slowdown, and his houses, he said with a mixture of amusement and chagrin, have been occupied by squatters. “There are squatters from all over the world there,” he said, “totally happy, living in exceptional houses with wonderful views. Last time I went by I met a group of Brazilian painters.”

Mr. Zaaijer clearly loves these homes, but he is skeptical about the contribution such structures will make. “We have six or seven million houses in Holland,” he said, “and this will always be a marginal addition to them.”

Mr. Betsky is not quite so pessimistic, but he acknowledges significant obstacles. “In most of the designs I’ve seen,” he said, “the houses are isolated objects connected to the shore by a thin umbilical cord.”

“A luxurious isolation tank seems to be the destiny of many Dutch lakes and rivers,” he added. “Might there be a community like what one finds in Southeast Asia, where the houses connect to each other as well? I am still looking for good examples.”

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