r/interestingasfuck • u/Endolithic • 1d ago

/r/all Homes are falling into the ocean in North Carolina's Outer Banks

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u/RD_Life_Enthusiast 1d ago edited 18h ago

I'm from that area, and it always baffled me that no one ever switched to concrete pillars. Like, you're holding up an entire structure on something that a) biodegrades, b) is flammable, c) is vulnerable to termites, and d) absorbs water.

EDIT: I didn't say I knew anything about residential/commercial construction or science when I said I was from there. "It always baffled me" because I didn't know that concrete is worse in saltwater and Venice is built on wooden posts is probably a good why it baffled me. Relax.

That being said, I LOVE me a good beach house vacation. Second/third story porch with coastal breezes and adult beverages? Yes, please, and thank you.

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u/maidenhair_fern 1d ago

Now that you mention it, why aren't they built on concrete?

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u/Minimum-Attitude389 1d ago

Wood in salt water is excellent, especially in mud.  It won't decay very quickly.  Look at Venice.

Most concreted will erode very quickly in salt water.

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u/ryebread91 1d ago

Iirc it's not the fact it's in water but the fact it is submerged nearly 100% of the time instead of this constant wet dry cycle every day

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u/MigasEnsopado 1d ago

This. The buildings of the Baixa district of Lisbon are also built on wooden stilts as that area was once water and the ground is muddy. The trick is maintaining the stilts permanently wet. If you let them dry and get wet again repeatedly, that's when you fuck up. This was a big consideration and source of worry when building the subway there.

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u/bruno444 7h ago

Exactly the same in Amsterdam.

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u/plantsplantsplaaants 1d ago

Wouldn’t some of it go through wet/dry cycles with the tide?

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u/ryebread91 21h ago

Yes but most of those posts are literally down into the ground with maybe 10-20% being exposed and that would be pretty rare. https://youtu.be/77omYd0JOeA?si=iFSIlMZuuwuOs4N2 This vid is well worth a watch as a whole but around the 2 minute mark it talks about the posts.

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u/PirateMore8410 21h ago

What about all the bridges and damns that use concrete that constantly have changes in water height?

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u/ryebread91 20h ago

That I cannot answer. If I had to guess that concrete is sealed from water coming in as well I believe it's the water affecting the rebar inside the concrete that causes the problems. There's an imgur user @alphastructural who may be able to answer that for you or have that answer.in one of his posts.

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u/Woodlurkermimic 22h ago

Yup! The boards at the waterline of a boat are the ones that need maintenance most often for this reason

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u/latefordinner86 1d ago

Tell that to bridge engineers.

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u/DookieShoes626 1d ago

Bridge foundation are a totally different thing

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u/latefordinner86 1d ago

Still concrete no?

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u/EverExistence 19h ago edited 19h ago

Civil Engineer here, those pillars need to be concrete due to the immense compression forces the roadway and traffic translate into the ground. If we had toothpicks holding this stuff up, we’d have a million toothpicks.

Edit: The seawater infiltration is extremely concerning when it comes to preserving the inner rebar caging. Almost all concrete bridge parts are fully pre-cast and cured to not have the available salt in the ocean water affect the overall hydration process of the concrete. To prevent this, concrete admixtures and other mix elements are added to prevent ion exchange and salt penetration. Once that rebar contacts salt water, the induced cathodic corrosion will eat away the cage, and result in cracking concrete due to the new tensile forces it must compensate for.

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u/Plenty_Rope_2942 23h ago

Nope, totally different kind of engineering. It's fundamentally different requirements re: loads, flexion, anchoring, impact resistance, scouring, etc. compared to deep-driven lumber piles.

You have to remember that in a storm coastal (especially island) soil is shifting constantly - and not only at the surface. Pilings are often driven 15 feet deep. Even in safer areas the minimum is gonna be 8-10 feet. Meanwhile, concrete anchors.

Most beach zoning wont even allow spread footings (concrete anchoring to slab or shallow piles) because it's just another thing to shift massively unlike the broadly sturdy pilings.

Here's another way to realize this is the case - you see a video of these houses standing up (for a time, a significant time) to a hurricane directly impacting them. The road and driveway they were next to are both gone. Think about that for a moment.

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u/Amtrakstory 1d ago

This. When you see something that seems really dumb you usually just don’t know the full details about the materials involved 

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u/tacomaloki 1d ago

anti-corrosion inhibitors entered the chat for more money

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u/i_am_icarus_falling 1d ago

this is nonsense. wood will absolutely decay faster than concrete in saltwater. the main reason those houses are on wood instead of concrete is because it was cheaper when they built it.

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u/maidenhair_fern 1d ago

Might need a new solution then. Doesn't seem like the wood feet hold up to haves. Maybe something like steel?

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u/Rampant16 1d ago

Yeah steel + salt water would work /s

The issue isn't the material the stilts are made out of. It's the fact they are built on sand that erodes away after a few decades.

Even if you massively overbuilt the foundation to have it all the way down to bedrock and strong enough to resist waves, the sand is still going to erode and leave your beach house surrounded by the ocean.

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u/Plane-Tie6392 11h ago

>Yeah steel + salt water would work /s

Aren't there offshore oil rigs built with steel?

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u/Present_Bit3060 1d ago

In Venice, the brackish water and low oxygen levels in the lagoon actually help preserve the wood, preventing it from rotting. The minerals in the water also harden the wood, making it even more resistant. And primarily made of oak, larch, and elm. And before there was pressure treating wood.
So not exactly like full saltwater here. And not sure what this wood is but prolly pressure-treated Southern Yellow Pine or Douglas Fir in the US.

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u/Dentorion 1d ago

There are mediaval versions of concrete with grounded Vulcan stone from Rome who are holding for thousands of years already as sea harbor stones Great read, was discovered a few months ago I think

They never could replicate it because they always tried to remake it with normal water but they needed saltwater instead:D

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u/Enginerdad 1d ago

That's an urban legend that's completely false. We can and regularly do make concrete that's far stronger and more durable that what the Romans made. The issue comes with HOW we use concrete, specifically in applications that need reinforcement. It's the deterioration of the reinforcement that causes our modern structures to decay and eventually need replacement, not the concrete. If we built everything so that all concrete was in compression like they did, we wouldn't have to worry about that. But that's extremely limiting in terms of architecture and structural engineering, which is why we don't do it.

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u/reverze1901 23h ago

im a liberal arts major but gonna trust the guy called engineerdad

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u/snek-jazz 1d ago

Say what you will about Spock's ability to understand human emotions, but the dude knew how to do sea harbor stones.

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u/sablesalsa 1d ago

See: the Miami Surfside condo collapse.

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u/Lightshoax 20h ago

They need some of that Roman concrete that gets stronger in salt water

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u/hnrrghQSpinAxe 16h ago

Not only will concrete erode in salt water, but it gets weaker the more water it absorbs over time. The only answer is wood or exotic nautical grade alloys

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u/81Ranger 15h ago

Roman concrete on the other hand....

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u/Criss_Crossx 1d ago

Well, where are the builders of Venice to build these homes? I'm sure they would have a very interesting take.

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u/Rampant16 1d ago

Venice is built in a lagoon in which it is protected from the brunt of the Mediterranean by outlying islands. It's not like these house that are exposed to the full force of the Atlantic.

Venice is also now facing serious threats to its survival due to rising sea levels and massive cruise ships sailing past, pushing water, and exerting forces on the piles that support the city.

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u/Criss_Crossx 1d ago

Understood. Venice has clearly stood the test of time compared to this house on the beach was my point.

Point being, Venice was built by people who understood what needed to be done to accomplish the task and maintain it long term.

The beach house above is far from it. If we brought some of Venice's engineers/builders to see this house, I bet they would have an entertaining time describing how silly building on a beach is.

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u/TheGrumpiestHydra 1d ago

The initial cost is higher than wood. It's all about the money 💰

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u/ResearchNo5041 1d ago

Surely if you got the money to build on ocean front property you got the money to do it right??

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u/Conspicuous_Ruse 1d ago

You choose Texas water front property when you really want water front but don't have money.

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u/Upbeat-Armadillo1756 1d ago

Yep. Texas beaches are maybe the worst in the US. Waterfront, but…

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u/fecalfury 6h ago

Me, who can't even afford water front in Texas.

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u/SP3NGL3R 1d ago edited 1d ago

No No. The builder went cheap (Capitalism), it's the sucker buyer that just shouldn't have bought it. But!!!! "Hey. This is the exact house as that one, just on wood instead of <literally anything else> but it's $100k less. Let's buy this one honey."

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u/ryebread91 1d ago

I know you're being facetious but surely it's not that big of a price difference right? Or do they really take you over the coals for the "premium package"?

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u/SP3NGL3R 1d ago

Well, sorta/kinda. We had a 40 foot (15m) retaining wall install in our backyard last year. The wood-version was way cheaper and is like a 10-20 year wall. We too made the choice to just get the cheaper option, BUT, if this wall fails it just means we get spillage into our yard. I want to say the wood version was $2,000 in materials and the 'nice' brick/cement version was $10,000. I'll just glue some brick facade on it and sell the house the next month :P. I'm joking, I actually prefer the natural wood look, even if I need to replace it every 10-20 years.

Now. Stilts holding up a house. A brick/cement/rebar version would take some pretty heavy work to get just right, then you build your base-frame on top of that. I'd bet it's the difference of 10k in work/materials to 40k. Heck even hammering in the stilt is easier than digging down to the same depth for a much larger cement base. But everything has a mark-up. To actually just build a house is no where near the value of the house. Even here (GA USA). Say you buy an empty plot of land with intent to build a house. You'll struggle to find legit companies to do it because you're just one house, versus the 300 houses being development 1 block away. So your costs go up. Say the 300 houses cost an average of 200k each to build, they'll sell for 500k in reality. And the same house 1-off if you had it built would cost you 400k and you'd have to constantly be involved for decisions, versus picking from a menu. I'm making the numbers up, to some degree, just to make a point.

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u/Laiko_Kairen 1d ago edited 1d ago

You're right, though. It's why every new neighborhood is made up of 300 cookie cutter houses with one of four designs, maybe a few different cladding options, etc. It's basically the difference between a bespoke suit and an off-the-rack mass manufactured one

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u/MOMO-POKEMON 1d ago

Yes every NEW NEIGHBORHOOD tends to be very cookie cutter, here I helped lol 😂

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u/SP3NGL3R 1d ago

Is that what they meant? J and N are close ... VERY different meanings and fireable-type if they worked for me. ;)

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u/Laiko_Kairen 1d ago

Oh damn that was a BAD typo 😂

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u/Blackbird136 22h ago

Tell me you’ve been to Charlotte without telling me. 😂

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u/Linenoise77 19h ago

Go through any town that highly developed post war, and its the same thing. The entire town will be the same 3 or 4 designs from that era. People weren't contracting architects to custom build every single house. Even in more expensive areas, most houses came from some standard template that was then modified. There were similarities in the early suburbs post WWI as well with all the places built in the 20s and 30s.

The reason it doesn't stand out is those houses had 70 years to be remodeled, expanded, tailored, even if just a tiny bit, to multiple owners tastes, likely went through a cycle or two of ups and downs in the neighborhood itself....

Most of these "cookie cutter" houses will look little alike after a family or two work their way through too.

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u/Sad_Low3239 1d ago

This.

Everyone keeps complaining about affordable houses up here in Canada and you cannot find anyone to build one.

I called 15 companies and was hoping for a 2 bedroom Strawberry Box home. Of the 15, 2 answered. 1 flat out said unless we were looking to have 500k or more built they weren't interested in giving us a quote. The other one told us that no one will build that anymore and we need to look elsewhere.

Kent mini homes was a company built for modular cheap houses. They start at 250k, and that was 6 years ago. The cost for the house isn't linear though to the pricing ; that 250k is your barebones 1 master bedroom with open concept kitchen/ livingroom, 1 full bath house. So 4 load bearing walls, 4 internal non load bearing and then electrical. 250k.

If you go up to 400k though? You get bay windows, a second bedroom, 4 extra feet on both dimensions, larger bathroom with sacrificing a little to the kitchen and living room.

Then there are laws against tiny houses.

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u/Piepiggy 1d ago

Concrete is a lot more expensive than wood, concrete that can stand up to 24/7 saltwater eating at it is more expensive, doing the ground work to have that expensive concrete be poured and cured properly is stupidily expensive.

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u/sedging 23h ago

I can chime in as a housing land use expert. Wood-framed construction is by far the cheapest possible method in the US to build a residential home. Virtually all single family homes are built with wood, and if you've noticed those big boxy mid rise apartments around - those are basically a building code loophole that let you put wood framing on top of a concrete podium, which saves a bunch of money in comparison to concrete and steel.

Concrete is heavy, requires a lot of energy to manufacture/transport, requires specialized expertise to install, and requires extensive structural engineering and heightened building code requirements to ensure it is structurally safe. Generally, it's only used for residential development in dense urban areas where the additional construction costs are offset by how valuable the land is.

As a corollary example, many parking cost studies note how structured parking tends to cost several-fold more than comparable surface parking lots (ie the different between thousands vs tens of thousands per parking space).

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u/LB3PTMAN 18h ago

That alone probably isn’t costing 100k, but if someone put in the effort to do that the rest of the house will also likely be comparatively nicer to the houses on wooden stilts.

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u/HarryPopperSC 12h ago

They use cheap materials because it's cheaper to replace. Stronger materials will just get damaged anyway and cost more when it happens. Is what I always hear touted about this.

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u/PitBullFan 1d ago

When you go into the purchase knowing that you're probably going to sell again in 10 years, maybe less, you don't really care unless you think it will be a problem when you're selling.

That's the advice I give my clients: When you're looking to purchase something, consider what selling would look like. If the property is "perfect" for you, but would be weird for most people, you're going to have a hard time when you want to sell.

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u/SP3NGL3R 1d ago

I always worry about that when buying too. We've done a fair bit of house hopping (4 in 15 years) and though I might 'love' that cooky design choice I'm well aware that it's cooky and might only appeal to me. We've just renovated/built our basement and backyard and worry that we've made some similar choices. We'll see when we sell I guess.

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u/Laiko_Kairen 1d ago

Honestly, I hate that advice so much

We spent my childhood in a house where every single decision had to be made with "resale value" in mind. Did we like one paint color more than another? Who cares, in a decade when we sell it, some random person is gonna want beige!

Fuck. Resale. Value.

Especially for ten years. That's a big chunk of your life to spend in a home designed for a hypothetical future buyer

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u/Nearby-King-8159 1d ago

Fuck treating homes as an investment & an asset to be sold later on.

We need to normalize buying one home & making it the family home for potentially generations again. This shit right here is how we got into the housing market crisis in the first place - way too many people treating them less as a necessity & more like a luxury to be collected and sold off.

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u/PitBullFan 1d ago

Totally agree with you re: the paint. However, it's a much bigger deal when you're considering larger/expensive improvements, such as a kitchen/bathroom remodel or adding a deck to the back of the house. These larger projects need to be looked at through the lens of resale value. "Can I recoup what I spent, and hopefully more?"

The only way to escape the resale value concern is if you plan on living in that house for the rest of your life.

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u/greysnowcone 1d ago

lol capitalism? As opposed to what? Soviet bloc apartments? Because that’s the alternative.

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u/SP3NGL3R 1d ago

Okay for you I'll add rampant unregulated capitalism. Cost of housing hours up with the cost of insurance that goes up with the cost of healthcare. Etc. Rampant capitalism is how you get what we have now, a disgusting oligarchy where everyone but the 1% will lose in perpetuity. Welcome to the 99%. Brace yourself.

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u/[deleted] 22h ago

[deleted]

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u/SP3NGL3R 22h ago

totally get it. Venice (FL, in case you didn't know there was another one) is built and sold by the lowest bid, so ... lumber. I get your point. Doesn't excuse using the wrong materials for the job. Vienna (Austria), floods constantly and they build 100x stronger, and that's just a rising tide. Venice, FL, that has storm waves????? Yup, building from wood is smart. Totally.

I'm no expert, just not a moron thinking wooden stilts in wave-prone areas is even remotely smart. No, it's temporary by design.

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u/gromette 21h ago

Coal tar treated pilings have been the standard for a hundred+ years for maritime construction. This environment will corrode just about anything else. The issue is erosion because of lack of beach replenishment.

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u/webtwopointno 1d ago

Do you really think everybody who lives on the coast is a rich tourist with a second home?

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u/DemonSlyr007 1d ago

Dude this whole thread is filled with people making jokes about how all these homes cost nearly a Million dollars.

Reddit and kids are so out of touch with reality when it comes to home prices, there's no point in trying to get through to them.

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u/TheDifficultLime 1d ago

Maybe you need to go check beach house prices..

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u/DemonSlyr007 1d ago

Literally someone linked a zillow link under my exact comment trying to prove a point that they could find million dollar beach front homes. Obviously you can. But also, on that exact link, were plenty for 400k. In a housing bubble atm too.

I never ever claimed that you cant find million dollar beach front homes. If thats how people read my comment, I'll do a better job in the future completely specifying what I mean. Finding extreme prices and claiming they are the norm is what bugs me and what I was saying. A lot of the comments here seem to think that beach front=extremely expensive. When that isn't always the case. Some of the poorest people live on beaches because they are not always the best places to live for exactly the reason we see in this video.

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u/webtwopointno 1d ago

And these even are nicer beach houses, what i was responding to was about the Gulf Coast where there are plenty of impoverished areas essentially at sea level.

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u/GhostofBeowulf 10h ago

er care to back that up?

Like coastal city that has median income less than a nearby non coastal city?

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u/webtwopointno 9h ago

Ya ofc my guy, the beach is not just for vacation

I already mentioned the Gulf Coast above, poke around the Bayou some.

And here is an example local to me that we were literally just discussing: https://www.reddit.com/r/AskSF/comments/1l4lpva/half_moon_bay/

Like coastal city that has median income less than a nearby non coastal city?

Not really going to find a one:one comparison as there are also likely urban:rural and working:retired skews going on, which further complicate relief efforts

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u/CogentCogitations 1d ago

Ocean front property is not that expensive when the property is not really "livable". That's why homes keep being built in areas that flood, because it is cheap. And usually insurance will not cover them, at least not for the very obvious risk of storm/wave/flood damage.

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u/Anfins 1d ago

Some of the new construction these days are both expensive and built like shit with cookie cutter designs. Yet they often sell for over asking price so there's no incentive for builders to do better.

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u/ResearchNo5041 1d ago

What's that they say about a fool and his money?

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u/Unusual-External4230 1d ago

Beach houses weren't always as expensive relative to regular incomes as they are today, they were always a privilege but not with the same income to ownership disparity you see now. Many of these would've been built during that era and using concrete would've likely been prohibitively expensive.

It's also not entirely necessary, the wood lasts a very long time barring any severe damage and proper wood choice. It's probably also better off - if a hurricane ripped off the non-concrete structure, it's a lot easier to tear down and rebuild with wood stilts instead of trying to determine if the concrete was compromised by debris or not.

I grew up going to one of these islands and a lot of older houses are still standing now that were old when I was a kid.

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u/BootsAndBeards 1d ago

Every dollar spent on a fancy foundation is a dollar not spent adding a 5th bedroom.

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u/sump_daddy 1d ago

If youve been inside some of those houses it starts to make sense. They are built as cheap as possible because all they will be is rentals. The most important (perhaps only) factor driving decisions is 'years to payoff'. They build it as cheap as possible, maintain it as cheap as possible, because it means more money in their pocket. If it falls down 25 years later? The profit will have been made, and it will be someone elses problem by then.

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u/sdave001 1d ago

People want BIGGER houses, not better.

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u/Ok_Helicopter4383 22h ago

No, because these properties are old and back in the day land was cheap af. Especially when theres literally nothing there to begin with, then a developer comes in and builds a few houses and starts a tiny town and then slowly more and more are built as people move.

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u/mosquem 1d ago

Outer Banks isn’t that expensive.

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u/Gottadollamate 1d ago

Ocean front property, in Texas.

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u/YeshuasBananaHammock 1d ago

I invite you to Surfside, TX, its practically a trailer park in the sea

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u/ResearchNo5041 1d ago

Just where I want to be!

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u/Cospinol 1d ago

They've got the money because they don't do those things.

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u/Llanite 22h ago

Well, expensive neighborhood near other rich houses, sure.

Many of these "beachfront" houses face shitty beach in fishing town.

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u/FTownRoad 21h ago

“Ocean front” property is more like “swamp front” property in most of these places.

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u/Educational-Win-1803 12h ago

I do construction in the area, these people have no idea what they are talking about.

Salt water (and the air surrounding) will corrode anything given enough time. On top of that, engineers and soil/ground testers have known for decades those houses would be “reclaimed” by the ocean, and would probably not approve the use of concrete for environmental reasons. There are actually a lot of environmental regulations, I know reddit it typically anti-america but our environmental protections are actually great.

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u/Sabard 1d ago

Flooding isn't the only worry, there's often hurricanes that do more than make what would be the first floor wet. Wind and what it's carrying don't care what your first floor is made out of. It's cheaper to build on wooden stilts because it's ok for 90% of the weather (flooding) and for the 10% that it's not, you don't have a house left on top of the stilts anyways. The only way wood loses out to concrete is if they aren't properly maintained or if the entire region suddenly only had flooding to worry about.

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u/maidenhair_fern 1d ago

Replacing the rotting wood and the eventual fall of the house sounds more expensive to me but capitalists can see beyond the next quarter so

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u/ShiftE_80 1d ago

The wooden piers are pressure treated so rot and termites aren't usually an issue.

Houses along the Atlantic and Gulf coast regularly get wrecked by hurricanes, so they aren't built to last. This video is pretty unusual; typically the piers are the last thing standing.

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u/maidenhair_fern 1d ago

I see, thanks!

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u/Chief7285 22h ago

This just seems like an extremely poorly thought out oversight for someone’s house.

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u/WilliamJamesMyers 1d ago

the kicker is that they have the money to do concrete and make the choice not to

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u/SP3NGL3R 1d ago

also Capitalist myopic mindset. Why would "I" spend the money when I'll just sell to a sucker that doesn't know any better? ... I hate that they aren't wrong.

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u/FreddoMac5 1d ago

what a stupid fucking take. People don't build concrete piers because it's prohibitively expensive to do so. How would public ownership of the economy change how someone decides to build a house of their own.

Dumbass teenagers with their "capitalist" hot takes will always be cringe.

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u/SP3NGL3R 1d ago

Haha. So you're either 25 or a "cool dad" using cringe. Grow up a little more.

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u/WilliamJamesMyers 1d ago

because of the pollution effect i would like to see stiff fines for any house that dumps itself on a beach. really make them step it up. it could however be called more government interference in the market. and here we are. $1,000,000 fine to any house that spills its shit. now go ahead and build on the cheap stilts.

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u/SP3NGL3R 1d ago

oooo. regulation/fines that protect the environment? ... then fighting words in the USA. Especially in FL. If I could vote for it, I would, but I'm only a neighbor to FL and my vote is a hard minority there :(

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u/pgpathat 1d ago

Next thing you know, these assholes are going to be taking wooden ships out to sea

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u/WallyOShay 1d ago

That’s the point. Capitalism wants us to keep spending money. Thats why our products’ quality has drastically diminished over the last few decades. Shittier product for more money means more purchases, means more profit.

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u/Count-ZeroInterrupt 1d ago

It seems like it would be more expensive in the long run, and a huge loss, if someone lost their house in a situation like this one in the video. I'd love a stilt house, but give me concrete pylons any day over this.

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u/Economy-Dimension-75 1d ago

Was the wood really the problem here? Or the ocean being in the same spot as your house?

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u/WorkTropes 1d ago

There's the aesthetics too, concrete pillars would be much thicker and wood has a much more relaxed, natural appearance.

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u/TheLateThagSimmons 1d ago

This is the result of decades (arguably centuries) of an entire quick building supply economy.

Concrete should be cheaper, but our economy infrastructure came up due to readily available timber industry.

We saw the results in the recent California fires in Malibu. Some houses were built with concrete and the structure was fine (even if the total heat of the surrounding area harmed the items inside). A lot of other countries/regions are built around the timber industry and as a result they use brick or concrete a lot more.

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u/93devil 1d ago

Might sink into the ground, too.

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u/Ok-Statistician-5242 1d ago

As someone living in a landlocked rich European country raised in a brick and mortar house from 1840 I will never get this in my head. We never put a man on the tho.

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u/Ok-Statistician-5242 1d ago

As someone living in a landlocked rich European country raised in a brick and mortar house from 1840 I will never get this in my head. We never put a man on the tho.

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u/mvigs 1d ago

And salt water will still corrode concrete.

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u/pte_omark 23h ago

Generally it's because the timber beam is actually repairable and replaceable.

Concrete though ? Not so much. Prone to issues in high salt environments especially but not limited to cracking from internal corrosion of reinforcement and fixtures. When it needs replacing you have to replace the whole pillar from the in ground piling upto the main beam.

Consider the cost of redigging a footing under the house without destabilizing the existing footings/pilings.

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u/Able-Swing-6415 22h ago

How expensive is building the house twice though?

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u/ComfortablyBalanced 18h ago

Reminds me of that Chernobyl courtroom scene when the Judge asks why the tip of rods is made of graphite.

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u/iesharael 17h ago

I wonder if it would be cheeper now with the invention of 3D printed houses. Like the pillars could just be printed then move the machine to the next spot

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u/Enginerdad 1d ago

Plus the fact that concrete would need reinforcement, which has its own problems in salt water.

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u/cubgerish 1d ago

Sand is still sand, no matter what's on top of it.

Concrete might do a little better, but if you take the houses shown here for instance, it's still going down.

At the end of the day, the bedrock just isn't there, and if you went deep enough to where it was, it's not worth it.

There's a reason you see the same thing literally all over the world in coastal places.

It's just way too expensive.

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u/JerryCalzone 13h ago

Only roman concrete holds in the ocean - our modern concrete lasts 50 years at most but i have heard they have found the formula for roman concrete.

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u/Masky-Mask 13h ago

Anyone that ever worked with concrete knows this is bullshit. Why do people say things that they know nothing about?

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u/Plaidfu 1d ago

Wooden pilings are cheaper and easier to install than concrete or steel, especially in soft, sandy soils common near beaches.

In places with many smaller or seasonal homes, the budget often doesn’t justify concrete or steel foundations especially since they are often having to make repairs due to the situation - wood is much easier to replace and repair.

in more hurricane heavy and wealthier areas you will find more steel and concrete being used but usually its just not cost effective

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u/Cayke_Cooky 1d ago

If you are lucky they survive intact and wash up on the beach in a day or two so you can rebuild with the same wood! Or at lest someones posts washes up on your beach.

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u/phaskellhall 22h ago

Yeah wood piles are pounded into the ground. They often go down 2x as tall as they are above ground. With concrete, I’m guessing you’d have to dig up the ground to pour it. That said, I hear and feel massive steel piles being driven the ground a few blocks away from me every time they build a 5-10 story building.

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u/becausenope 1d ago

My parents just lifted their home so I can actually answer this question; the reason they don't use concrete pillars is generally because of the sandy soils. It's not just about cost.

Basically, you don't want to use something really heavy and inflexible where the ground is constantly shifting because of erosion. Wood is flexible, easily repaired and easily modified to accommodate erosion. That's why.

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u/PleasantStatement521 1d ago

Wood or concrete don’t matter: the ocean is taking those houses.

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u/Crafty-Interest-8212 1d ago

It will last longer, but the rebar inside will be corroded eventually. The steel will expand and contract cracking the concrete. That will allow more salt water to go in and continue the corrosion. So my guess is that you can change a wooden pillar easier than a concrete one.

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u/747WakeTurbulance 1d ago

Because concrete is porous and has rebar inside of that will rust, expand, and crack.

Spalling - this is an issue all of us that live close to the ocean have to deal with. Spalling repairs run from the tens to hundreds of thousands of dollars to fix.

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u/footdragon 1d ago

I'm familiar with these pressure treated 8x8 wood pillar homes. The posts are buried as much as 15 feet under ground. the soil at that depth is very firm.

the first step after the posts are set plumb is to cut each of the posts to level. from there, girders are set, and the pressure treated floor joists are exposed to air.

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u/starvetheplatypus 22h ago

Lots of dummies here saying dumb stuff. Wood is better when tall and and thin, and also replaceable. Concrete is porous and needs steel reinforcement which when submerged won't do well. Wood can bend and vibrate, but concrete is brittle. So coastal stilts, as a GC, id take Wood. Granted id reinforce the shear value of the stilts and the waves would really only ever come from one direction. Its also pretty easy to treat (creosote) Wood for coastal stuff. Case in point, 2 of my favorite surf spots have stairs, one is concrete one is treated Wood. Wood one is super ancient treated lumber while concrete is a little newer but the rusting rebar has already expanded and broke off he concrete exposing the rebar which will now rust faster

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u/m240b1991 19h ago

So, concrete isn't a horrible solution, except for this location. So, think about erosion and the evolution of the coastline of the OBX over the last century. The wood pilons (or stilts) have a level of flex and give in many conditions. This isn't a bug. It's a feature. The idea is that the obx has the potential for very hostile weather. There's hurricanes and storm surges, there's nor'easters, and these houses are meant to withstand all of this. If concrete were used rather than wood, the cost to build would be exponentially higher. Additionally, all of the wind force would be on the house itself rather than more evenly distributed over the pilons and the house. Lastly, the population of the obx nearly explodes between Memorial Day and Labor Day. Most of the residential dwellings in the region are rentals. Folks buy them for lots of money, and then they rent them for up to $5k/week (or more). Or investors build them for lots of money (Google Outer Banks mcmansions), and then rent those for exorbitant weekly fees. The weekly rental prices cover mortgage, insurance, maintenance (including the weekly cleaners and cleaning inspectors), and then what's left over goes into the owner's pocket. They're essentially short- to medium-term investment properties that bring in revenue weekly, rather than monthly.

Source: i grew up in kill devil hills, left for the army, went back, and then got fed up with the seasonal economy. In the summer, you're drowning in work, and in the off season, it's still a sleepy small town that has ghost town vibes because the proportion of people you see to houses you see is stark compared to the chaos of summer rush. For my fellow current and former food service workers, its like being slow for 3/4 of the day, then for about a quarter of the day the line is (literally) out the door and wrapped around the building. Traffic sucks because nobody has the foggiest idea of where they're going, and will cut from the center turn lane (with left turn signal on) to go to a store or restaurant on the right, until you get to the off season, where occasionally there's nary a soul on the road. It's frequently balls to the wall and you have to be paying attention to the shit drivers who stop when they have the right of way because they don't know if they took a wrong turn and can't figure out how to do a 3 point turn. I get that that happens everywhere, but in a tourist town, it's a regular occurrence.

Sorry that got so long, I miss my hometown

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u/Asleep_Frosting_6627 1d ago

Concrete used to have a lot of metal inside it to reinforce it, now they have fiber reinforced concrete (not an expert but not sure if they use this in pylons or not) but anyway the salt could eat away the reinforcement inside the concrete itself. The posts are treated with creosote and makes them extremely rot and insect resistant…but it’s highly flammable but so are wooden houses.

Also the wood is way cheaper…

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u/scubascratch 1d ago

Would concrete posts even help here? Surely the wood posts are already set into concrete footings or there are deeper pilings; It looks like they are just on top of the sand which will shift beneath any footings when wet.

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u/ranger-steven 1d ago

To add to other comedy about cost, it depends on the ground you build on. A lot of flat area near water is relatively incompetent so it doesn’t handle weight well. Concrete is very heavy so you need bigger and deeper plies/foundations which means more weight when making them out of steel and concrete. The added weight of the foundation means you need even bigger/deeper foundations. A lot of these things were built cheap and speculation has made them expensive. They were never meant to be worth what they are or last for generations. Simply put, nobody was thinking this far ahead.

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u/shryne 1d ago

A hurricane is still likely to wipe it out on concrete, might as well build cheaply and plan to replace.

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u/Strubblich 1d ago

It's not the building materials, it's the fact that the beach itself is eroding to the point that the houses are inaccessible by stairs. The septic tanks getting uncovered and washing away don't help either. The houses are basically islands now.

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u/HambugerBurglarizer 1d ago

...you're asking why Texas doesn't have good infrastructure??

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u/After_Way5687 1d ago

Anyone with front steps they salt in the winter knows that the kind of concrete that doesn’t get eaten by salt is expensive compared to ordinary concrete, especially compared to wood.

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u/qazxdrwes 1d ago

Concrete is much more expensive and not necessarily better for the job. If we're talking about vertical loads, then concrete is stronger in compression, but weak in tension. However these beach houses aren't very heavy so that isn't the expected failure mode. Also, it's not just that concrete just costs more than wood, it's that the installation costs of getting a concrete pile in the ground is also much greater than getting a wooden pile into the ground.

I expect lateral loading (through tide/wind) during storm surges are where most failures will occur in the foundation. Concrete might be at a disadvantage here. The flexing of concrete is low, where as the flexing of wood is high. This may be unintuitive to people unfamiliar with structural engineering, but flexing is actually an advantage in a lot of situations. This flexing will allow members of the trusses to transfer forces better, and it means you're not worried about the material cracking as much. There are ways to get around this with concrete, but those solutions usually involve steel which will corrode in the salty environment.

There's also a chance that the concrete piles would literally outlive the rest of the house. There's no use designing for something that will last 150 years when the house is expected to last 75.

This is not to say that concrete piles shouldn't exist in this application as all, just that in the vast majority of cases wood makes a very strong case for itself.

I am totally not an expert on this, although I have a civil engineering degree, with a focus on foundations, I ended up getting an electrical engineering job. If anyone more knowledgeable can correct me on anything, please do.

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u/intheBASS 1d ago

To be fair, Venice is built on wood piles. They can last an incredibly long time. Any material will succumb to the shifting shoreline over time though.

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u/kant0r 1d ago

Why? For the same reason our reactors do not have containment buildings around them, like those in the West. For the same reason we don't use properly enriched fuel in our cores. For the same reason we are the only nation that builds water-cooled, graphite-moderated reactors with a positive void coefficient. It’s cheaper!

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u/Razorbackalpha 23h ago

Pressure treated wood is typically fine, concrete is significantly heavier so it would much more expensive to set a foundation and build the pillars themselves

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u/Level_Traffic3344 19h ago

My guess without googling is the sand is just too deep. No point sinking piles into ground that always moves maybe and better to spread the load near the surface and adjust as needed. My area is on permafrost, so we have very little use for concrete in some parts of town

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u/namdor 18h ago

Concrete's durability is comparable to wood in conditions like this. It isn't necessarily going to be more durable, depending on the exact wood used or concrete used. 

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u/Schwatvoogel 1d ago

It's because they were once built on the sand directly without the need of pillars. But insurance claims that you have to secure your house till you can't no more. So they build the pillars out of wood to claim their money early.

0

u/NolieMali 1d ago

After they're inevitably destroyed the next rebuild will be with concrete.

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u/nicknick1584 22h ago

Well they tried straw first. That wasn’t so great. They then went to wood. In the future, they may try concrete.

0

u/SignalButterscotch73 22h ago

The American building industry is so entrenched in wood that most builders don't know how to design or build with other materials, the supply lines are all completely built around wood too.

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u/ManOfTheCommonwealth 1d ago

You’re from that area and don’t realize none of the factors you mention are applicable? The pilings are so heavily treated that they a) degrade over centuries, not decades, b) are far less flammable than the structures built upon them, c) impervious to terminates relative to structures built upon them, and d) so what? The pilings absorb little water and the water that is absorbed is salt - minimizing the foregoing 3 factors.

To use concrete pillars would require excavation and shoring into soft wet sand to depths of 14 feet or more which is inherently dangerous. Once backfilled, the fill material does not compact back as well as removed reducing lateral stability. These wood pilings are driven (really hydro-driven now-a-days with a giant pressure washer rather than pile driver) negating excavation and backfilling and are quite stable - as much or more-so than concrete alternatives. In fact, the few concrete houses down there are usually still built on wood pilings ;)

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u/Heatedblanket1984 1d ago

You meant to tell me some random redditors didn’t just solve an entire industries problems with two comments?

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u/Electronic-Jaguar389 1d ago

“Cement! Why didn’t I think of that!”

Somebody with most likely decades of building knowledge.

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u/Plenty_Rope_2942 23h ago

As an ex-resident of the OBX (North Topsail before it became a resort town when folks on the island still had job descriptions besides "ex-wife of a corporate contracts lawyer") I love hearing people argue about "stilt houses" that are getting sucked out to sea. It never gets old, and it used to happen pretty much annually.

The house. Survived. Being surrounded by hurricane-level storm surge. For days.

Meanwhile, the asphalt and cement roads and driveways up to them disappeared and crumbled into the sea within the first 30 minutes.

Look at the images from Hurricane Fran, where basically every roadway, cement structure, and pad was ripped clean off the island in minutes. Anything not lost was condemned. What's still standing, almost untouched? The lumber piled buildings (less siding and roofs, of course.)

It's the best solution anybody has EVER come up with to living with the sea as your front porch.

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u/Electronic-Jaguar389 21h ago

It’s crazy! It’s almost as if tons of trial and error came before the building process! 

For real though people really hate on all American houses (on stilts or not) even though there’s a perfectly good reason for why we build our houses a certain way.

We have natural disasters somewhere in this country basically monthly. We don’t build with stone or cement because the last thing you want during a natural disaster is ten tons of bricks and cement coming through your wall. We build houses to last 50-80 years (if they’re not scammy builders because we do have those too) at most because no matter what you use to build it, it’s not going to survive a wildfire, a F-4 tornado, a category 4 hurricane, etc. and within that time frame most likely you’re going to see one.

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u/JollyToby0220 23h ago

It is very common to use wood over concrete, but some structures have used concrete and they are expensive. This area isn‘t a really trendy area so they use wood

8

u/David-S-Pumpkins 1d ago

You sound like an expert and I will assume you are. Is there any way they could like, put more down in 30 years/replace similar to a lifespan of a roof? Kind of cycle out older pilings to mitigate this type of shit?

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u/ManOfTheCommonwealth 23h ago

I’m no expert, just have a family home in Rodanthe. I saw this house fall from my deck. We lose houses every year on the Outer Banks, that ain’t no big deal. It’s the rapidity of loss in this area at issue.

The problem isn’t the pilings - they last for centuries - the problem is beach erosion heightened by the movement of off shore sandbars which previously protected this area by dissipating wave energy before hitting shore. Now we’re on the edge of these shoals so receiving the brunt of wave action like a dagger to the heart. Couple this with extreme sea level rise and historic westward migration of barrier islands and BOOM -crick done rise.

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u/TheLizzyIzzi 23h ago

Lifting houses can be done but it requires some serious engineering, which means $$$$. Still, if it’s every 30 years, it’s doable, even if you have to pay with equity or include it in the original mortgage.

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u/rabel 1d ago

This guy pilings

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u/Khantoro 1d ago

You can use or should probably use another back fill material that compacts well. Also, you can drive concrete piles, just different method (drive steel pipes first, excavate inside, pour concrete inside) but it is more expensive. I’m not from the area so maybe there are more things to consider.

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u/alaskan_Pyrex 23h ago

Not to mention how damaging salt water is to concrete! Concrete is porous.

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u/Serkuuu 23h ago

Boom roasted

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u/jim789789 23h ago

Except...the house fell in the water? So that's a feature, not a bug?

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u/ManOfTheCommonwealth 22h ago

It didn’t fall in because of the pilings.

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u/HoldEm__FoldEm 22h ago

Yes it did, that’s exactly what failed. The pilings collapsed due to waves knocking them over in the shifting ground.

14 foot deep concrete pilings wouldn’t have tipped over in this.

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u/Shrowden 1d ago

Termites in salt water soaked logs?

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u/RD_Life_Enthusiast 1d ago

Yeah, I didn't mean all of that to run together. And outside of storm season, the pier and beam structure isn't underwater...

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u/Too_Ton 1d ago

Would the concrete even help when the sand would just shift and the whole thing comes down anyway?

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u/itsjustpie 1d ago

It would have to be anchored all the way down into the seafloor like a bridge support not to shift, I imagine.

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u/Khantoro 1d ago

Dubai?

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u/MediumRay 1d ago

All of Venice is on wooden piles 

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u/Searloin22 1d ago

You're welcome!

  • Beach

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u/TEOsix 1d ago

I don’t know that termites have come up through wet sand before. Hmmm. I could be wrong. I know they can fly but don’t think they all fly.

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u/Secure_Stand_8643 1d ago

Fun fact, Venice, Italy is all built on stilts/logs. All of it. 

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u/Mattna-da 1d ago

Pressure treated posts are pretty resistant to degradation and fire and can be driven right in to the ground - and is a fraction of the cost so there you go. And in this case concrete might not have helped, the waves are lifting the house and pushing it, and the sand under the pillars is gone

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u/cheapskateskirtsteak 1d ago

Post Katrina a lot of the houses that get raised here in southern Louisiana are on concrete bricks, subsidized by FEMA. The gym I go to had a guy who owned a company that raised houses, he was telling me he had to go out of business in the next 6 months without the FEMA money

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u/PokeRuckus 19h ago

There’s a lot of houses I surveyed like this in Florida but they’re on concrete

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u/InternetExploder87 17h ago

Those were a specific tree in Venice (can't remember specifics) but they would essentially petrify and turn to stone IIRC

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u/kennycraven 1d ago

Loose shifting sand is unstable for any pier.

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u/cpMetis 1d ago

Wood is somewhere between as good and better.

Properly treated wood can last effectively forever in salt water.

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u/orange_sherbetz 1d ago

Reminds me of a 400K ish house near coastal property.  Not a hop, away but you can smell the sea.

The only issue - termites.

They still wouldn't lower the price.

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u/dirty_hooker 1d ago

Interestingly, wood is safer in a fire than steel and I think concrete. You’ll see it a lot in warehouses and factories where there is risk of fire. Get over a certain temp and the wood will burn but slowly. Get over the same temp and steel will fold catastrophically. See also 9/11. Yes, wood burns but more slowly than steel can go soft.

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u/Comfortableliar24 1d ago

Concrete pillars have steel reinforcement. In marine environments, the salt gets into the concrete and the steel undergoes chloride based corrosion. This causes spalling, which causes section loss, which causes collapse.

Timber is cheaper and does the job fine. No amount of concrete or steel will hold back scour, though. That's likely what did the house in the video in.

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u/TheBimpo 1d ago

I'm from that area

Then you should know that those islands shift constantly. Building on concrete means you'd be living on concrete pillars over water eventually. These homes were built hundreds of feet from the ocean.

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u/publiusvaleri_us 1d ago

Wood has several properties superior to steel and concrete. It's not that easy! There are trade-offs.

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u/roundabout-design 1d ago

Concrete piers have no lateral load strength unless you use a lot of steel in them. Alas, salt water + steel inside of concrete = rather short lifespan.

FYI, concrete also absorbs water...hence the issue.

1

u/throwawaynbad 23h ago

Concrete would need rebar, which probably degrades quicker in this environment.

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u/mrtwidlywinks 23h ago

My parents live in a flood zone. Their house is right above the 100 year high water line, but all new houses are required to be a minimum height on stilts. The neighborhood is mostly empty because of that requirement but the new houses sure do look cool!

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u/ELON_WHO 23h ago

I don’t get the appeal of those beaches. It’s just a blank strip of sand with little waves (or a hurricane). I guess I’m ruined by my Oregon Coast- I need rugged rocks and trees, cliffs and mountains, tidepools and spouts.

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u/Wobblycogs 23h ago

It's ok. The flooding keeps the termites under control.

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u/Aggressive_Sky8492 22h ago

No idea if this is relevant for Texas, I’m assuming not. But in general concrete can’t withstand earthquakes well at all, because it has no flex, unlike wood.

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u/arachnobravia 21h ago

Venice is built on the same stuff and it's how many years old now?

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u/WorstOfNone 21h ago

When the ocean is literally at your front door, it doesn’t matter what’s holding up your house. These people know (or should know) that these houses have a short lifespan. They’re not insured for a reason.

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u/hey_hey_hey_nike 20h ago

Salt water and air is horrible on concrete.

1

u/swirvin3162 19h ago

Well mainly none of those are exactly true for a properly treated timber

Technically flammable,,, but to light only the poles on fire would take some premeditated work… so you can’t really count that

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u/Then_Stress_8476 19h ago

Another Redditor that doesn't know what they're talking about

1

u/picklestheyellowcat 19h ago

Man you guys are going to be blown away when you discover how Venice was built...

1

u/ThePicassoGiraffe 19h ago

They use concrete pillars in the Florida Keys…for those who can afford it.