Check out the episode:
You can find the shownotes through this link.
Are you interested in amphibious architecture as a potential solutions for floods?
Our debate today works with the article titled Thriving with water: Developments in amphibious architecture in North America from 2016, by Elizabeth English, Natasha Klink, and Scott Turner, presented at FLOODrisk 2016 – 3rd European Conference on Flood Risk Management.
This is a great preparation to our next interview with Elizabeth English in episode 428 talking about amphibious architecture solutions from all over the world.
Since we are investigating the future of cities, I thought it would be interesting to see a resilient alternative to traditional flood defences in amphibious construction. This article introduces amphibious architecture, structures that float on the surface of rising waters, which provides greater adaptability and maintains neighbourhood character.
[intro music]
Welcome to today’s What is The Future For Cities podcast and its Research episode; my name is Fanni, and today we will introduce a research by summarising it. The episode really is just a short summary of the original investigation, and, in case it is interesting enough, I would encourage everyone to check out the whole documentation. This conversation was produced and generated with Notebook LM as two hosts dissecting the whole research.
[music]
Speaker 1: imagine standing in your living room as flood waters just completely breach your neighbourhood. Instead of dirty water, seeping under the front door and ruining absolutely everything you own, your entire house gently lifts off the ground just floating safely above the surge.
Speaker 2: It sounds like science fiction, but it’s an actual engineering reality, and frankly, it’s a reality we desperately need to consider because for centuries, our civilization’s approach to water has just been this brute force contest, right? We build massive concrete levees and rigid flood walls, plant our feet, and just hope the barricades can absorb the pressure,
Speaker 1: which they frequently don’t. The water eventually throws a knockout below. We all remember the tragic result in New Orleans in 2005. Compounding levy failures left 80% of the city underwater in the aftermath of Hurricane Katrina. The whole control and conquer era of flood management is fundamentally failing as sea levels rise and extreme weather multiplies.
Speaker 2: It’s an outdated model.
Speaker 1: So today we’re examining a radical paradigm shift. What if we stopped trying to stand our ground? Amphibious architecture allows homes to rest on the earth under normal conditions, but float dynamically during a flood. I’m arguing that it’s not just a novelty. It is an absolute necessity to avoid the severe structural risks of our current adaptation strategies.
Speaker 2: I have to push back on the idea that this is a broad scale necessity. Conceptually living with water rather than fighting it is incredibly elegant, but practically it is a regulatory and financial nightmare. I’ll be arguing that amphibious construction faces just insurmountable hurdles that relegate it to a fascinating niche rather than a viable global solution.
Speaker 1: Let’s start by looking at the baseline problem, though. Historically human settle in floodplains, we rely on them for fertile soil, for river transportation, moderate temperatures. We can’t simply abandon these regions, but our default adaptation strategy right now, static elevation, which literally just means putting houses permanently up on stilt. It has a fatal flaw.
Speaker 2: The wind vulnerability.
Speaker 1: Exactly. When you permanently raise a house 10 feet in the air, you aren’t just exposing it to faster winds, higher up, you are allowing wind to rush underneath the structure, which creates massive uplift. The house essentially becomes an airplane wing.
Speaker 2: Right. It’s aerodynamic in all the wrong ways.
Speaker 1: Yeah. Elevating a building statically is basically raising a sail in a hurricane. The data shows that increasing a roof’s height from three meters to 10 meters raises the expected annual win-loss by 66%.
Speaker 2: And amphibious homes avoid that by staying low to the ground. Most of the time,
Speaker 1: they maintain a low aerodynamic profile day-to-day. Let me just walk through exactly how a retrofit works because you don’t have to demolish. The house crews excavate underneath the existing floor joists. They insert a sturdy steel subframe. Pack it with buoyancy blocks and secure the corners to deep driven vertical guidance posts.
Speaker 2: Okay, so the posts keep it in place.
Speaker 1: Yes. When the flood hits the house, slides vertically up those posts, floats on the water, and then drops back down precisely into place when the water recedes. It solves the water problem without inviting destruction by wind.
Speaker 2: The mechanics are clever, I’ll give you that, but let’s talk about what actually happens in a severe flood because floods are rarely just static. Rising bathtubs of water.
Speaker 1: True.
Speaker 2: They bring heavy, fast moving debris. So what happens to those vertical guidance posts when a multi ton tree trunk or a shipping container smashes into them at high velocity? These posts aren’t just simple sliding tracks. They have to withstand immense lateral force
Speaker 1: while debris is a massive threat. Absolutely, but that’s exactly why these vertical guidance posts are engineered with high strength steel and concrete reinforced housings. They’re explicitly designed to endure those extreme lateral impacts.
Speaker 2: Even so, if a static home on concrete stilts takes a severe hit, the structure might be badly compromised. Sure, but it generally remains tethered to the earth. If an amphibious home’s guidance system buckles under a debris strike,
Speaker 1: you’re assuming a complete sheer failure,
Speaker 2: which is possible. If it happens, the entire house detaches from its moorings. It becomes a massive floating projectile itself crashing into neighbouring homes.
Speaker 1: That assumes a catastrophic failure of the engineering, which frankly happens with traditional levee systems and stilt homes too. The physical engineering is highly reliable. People actually ask a much more grounded question, which is if the house floats 10 feet into the air, what happens to the plumbing, the sewage, the electrical lines,
Speaker 2: right? Because a floating house is useless if it rips its own plumbing outta the ground.
Speaker 1: Exactly. Which is why the mechanics rely on flexible coiled utility lines. Think of them as umbilical cords for the house. They use this durable marine grade flexible piping with slack built in. So as the structure rises, these lines uncoil and extend maintaining power and sanitation, and then they safely recoil as the house settles back onto its foundation.
Speaker 2: Okay? But we can build the strongest steel guidance posts and the most advanced coiled plumbing in the world. Engineering. Marvels don’t matter if no one can actually afford them. Let’s look at the financial reality here. 30% of the global population lives in areas vulnerable to sea level rise,
Speaker 1: mostly in low income deltaic and riverine regions.
Speaker 2: Exactly. Places like the Mekong Delta or the lower Mississippi, an amphibious retrofit, like the models we’ve seen in places like Port Maria or Bliss pastures. Runs between 26,000 to 32,000 Canadian dollars. That is more than the median annual income for a lot of families in these highly vulnerable zones. When you’re looking at impoverished floodplains, an elaborate secondary foundation is just a luxury solution masquerading as a practical global remedy.
Speaker 1: I think you’re looking purely at the upfront price tag without weighing the catastrophic cost of inaction. Over the last 20 years alone, floods have displaced 1.1 billion people. They’ve caused $1.65 trillion in damages. The cost of doing nothing is literally bankruptcy. Entire communities are wiped out overnight.
Speaker 2: I’m not advocating for doing nothing, but 30 grand is 30 grand.
Speaker 1: But more importantly, the technology absolutely can be adopted for low income areas.
Speaker 2: How you just detailed a highly complex steel subframe.
Speaker 1: It doesn’t have to be western style, concrete, and steel. Look at the lift house built in DACA Bangladesh back in 2011, or the various localized proposals by the Buoyant Foundation Project. They swap out the expensive materials for cheap local alternatives like bamboo,
Speaker 2: bamboo for the subframe
Speaker 1: and for the buoyancy blocks. Instead of using expensive EPS foam, you know that standard rigid expanded polystyrene we usually see in commercial construction. They use thousands of empty recycled plastic water bottles.
Speaker 2: Wait, really just bound together under the house?
Speaker 1: Yes. Bound together in lightweight cages. Under the structure. EPS foam is highly refined and heavily taxed. Empty plastic water bottles are virtually free, and they provide immense buoyancy for a fraction of the cost. If the labour is donated by the community through sweat equity, the retrofit costs drop dramatically. Down to roughly 14,000 Canadian dollars. That makes it a highly adaptable, localized solution.
Speaker 2: Okay, but let’s follow that scenario. A community pools their resources. They gather the bamboo, they recycle the bottles, put in the sweat equity, and they hit that $14,000 mark. They immediately crash into an invisible, insurmountable barrier. Which is the bureaucracy,
Speaker 1: the Federal Emergency Management Agency in the US and similar regulatory bodies globally. Yes. The regulatory reality is a massive bottleneck. FEMA simply does not recognize amphibious construction as an equivalent to static elevation
Speaker 2: because their risk models.
Speaker 1: Their models require the traditional house on stilts
Speaker 2: for a building to be considered protected above the 100 year flood level.
Speaker 1: Because FEMA’s risk models and actuarial tables are based entirely on historical static data, they literally don’t know how to mathematically price a dynamic moving structure,
Speaker 2: which creates a devastating ripple effect without FEMA’s recognition. Homeowners are barred from the National Flood Insurance Program, the NFIP. If you live in a designated flood zone and have a federally backed mortgage, you are legally mandated to carry flood insurance. If FEMA refuses to recognize your amphibious house, the NFIP won’t cover you. If the NFIP won’t cover you, your bank will literally call your loan. You’ll lose your home. You simply cannot scale a housing solution in the modern market if the regulatory bodies actively prevent citizens from ensuring or financing their properties. Bureaucracy kills the scalability.
Speaker 1: I hear you. But we shouldn’t let bureaucratic inertia dictate our survival strategies. Regulations must eventually adapt to physical realities, not the other way around. And actually, FEMA did agree back in 2013 to allow amphibious retrofits for existing homes, even if full insurance eligibility is still caught up in red tape. The cracks in the bureaucracy are already forming,
Speaker 2: but allowing a retrofit to exist is very different from financially backing it. So working class people can actually afford it.
Speaker 1: Sure. But the sheer urgency of climate change and land subsidence is going to force their hand. Look at the Native American band on Isle of John, Charles, and Louisiana. The shrinking land and rising sea levels have left them with only seven of their original 26 structures remaining. They’ve been forced to accept relocation grants completely losing their traditional homeland.
Speaker 2: It’s a tragedy. Absolutely.
Speaker 1: Regulatory bodies won’t have a choice but to update their archaic rules when entire towns are faced with either adapting dynamically or just being completely wiped off the map. Amphibious architecture could keep those communities intact.
Speaker 2: Urgency doesn’t rewrite actuarial tables overnight. Look, we definitely agree that the traditional control and conquer era of levies is failing, and you’ve successfully highlighted the severe, often overlooked wind risks associated with static elevation. I remain highly sceptical that amphibious architecture is the ultimate scalable answer. From my perspective, it remains a fascinating, highly situational concept that is bogged down by structural complexity, prohibitive upfront costs, and rigid insurance regulations that won’t just magically disappear.
Speaker 1: I view it as an absolutely necessary adaptable paradigm shift for our future. We have to harmonize human settlement with nature’s rhythms rather than pointlessly trying to block them out for anyone wanting to dig deeper into how this works in practice. There are brilliant case studies in the material like the float house in New Orleans.
Speaker 2: It is definitely worth looking into.
Speaker 1: Grappling with these complex adaptation strategies really forces us to rethink our entire relationship with the natural world. So we leave it to you to decide in the escalating match against a changing climate should the future of our housing stubbornly stand its ground. Or is it time we learn to float?
[music]
What is the future for cities podcast?
Episode and transcript generated with Descript assistance (affiliate link).
What is The Future for Cities? Podcast 
Leave a comment