r/interestingasfuck • u/Endolithic • Jun 06 '25

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

Enable HLS to view with audio, or disable this notification

66.1k Upvotes

91% Upvoted

8.5k comments sorted by

View all comments

Show parent comments

375

u/maidenhair_fern Jun 06 '25

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

346

u/Minimum-Attitude389 Jun 06 '25

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.

164

u/ryebread91 Jun 06 '25

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

152

u/MigasEnsopado Jun 06 '25

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.

2

u/bruno444 Jun 07 '25

Exactly the same in Amsterdam.

3

u/plantsplantsplaaants Jun 06 '25

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

2

u/ryebread91 Jun 06 '25

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.

2

u/PirateMore8410 Jun 06 '25

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

1

u/ryebread91 Jun 07 '25

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.

1

u/Woodlurkermimic Jun 06 '25

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

31

u/latefordinner86 Jun 06 '25

Tell that to bridge engineers.

4

u/DookieShoes626 Jun 06 '25

Bridge foundation are a totally different thing

1

u/latefordinner86 Jun 06 '25

Still concrete no?

2

u/Plenty_Rope_2942 Jun 06 '25

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.

7

u/Amtrakstory Jun 06 '25

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

4

u/tacomaloki Jun 06 '25

anti-corrosion inhibitors entered the chat for more money

3

u/i_am_icarus_falling Jun 06 '25

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.

2

u/maidenhair_fern Jun 06 '25

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

11

u/Rampant16 Jun 06 '25

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.

1

u/Plane-Tie6392 Jun 07 '25

>Yeah steel + salt water would work /s

Aren't there offshore oil rigs built with steel?

5

u/Present_Bit3060 Jun 06 '25

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.

2

u/Dentorion Jun 06 '25

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

12

u/Enginerdad Jun 06 '25

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.

3

u/reverze1901 Jun 06 '25

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

2

u/snek-jazz Jun 06 '25

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

1

u/sablesalsa Jun 06 '25

See: the Miami Surfside condo collapse.

1

u/Lightshoax Jun 07 '25

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

1

u/81Ranger Jun 07 '25

Roman concrete on the other hand....

0

u/Criss_Crossx Jun 06 '25

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

9

u/Rampant16 Jun 06 '25

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.

2

u/Criss_Crossx Jun 06 '25

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.

0

u/hnrrghQSpinAxe Jun 07 '25

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

525

u/TheGrumpiestHydra Jun 06 '25

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

248

u/ResearchNo5041 Jun 06 '25

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

48

u/Conspicuous_Ruse Jun 06 '25

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

14

u/Upbeat-Armadillo1756 Jun 06 '25

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

208

u/SP3NGL3R Jun 06 '25 edited Jun 06 '25

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."

34

u/ryebread91 Jun 06 '25

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"?

48

u/SP3NGL3R Jun 06 '25

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.

25

u/Laiko_Kairen Jun 06 '25 edited Jun 06 '25

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

4

u/MOMO-POKEMON Jun 06 '25

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

3

u/SP3NGL3R Jun 06 '25

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

1

u/Laiko_Kairen Jun 06 '25

Oh damn that was a BAD typo 😂

3

u/SP3NGL3R Jun 06 '25

Oh come-on!!!! Why not leave the hate-speech typo? :)

It was so bad you actually could've gotten away with the NEW neighborhood cover-story on the news.

1

u/Blackbird136 Jun 06 '25

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

1

u/Linenoise77 Jun 07 '25

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.

2

u/Sad_Low3239 Jun 06 '25

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.

1

u/Piepiggy Jun 06 '25

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.

1

u/sedging Jun 06 '25

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).

1

u/LB3PTMAN Jun 07 '25

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.

1

u/HarryPopperSC Jun 07 '25

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.

3

u/PitBullFan Jun 06 '25

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.

3

u/SP3NGL3R Jun 06 '25

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.

1

u/Laiko_Kairen Jun 06 '25

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

2

u/Nearby-King-8159 Jun 06 '25

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.

1

u/PitBullFan Jun 06 '25

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.

2

u/greysnowcone Jun 06 '25

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

1

u/SP3NGL3R Jun 06 '25

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.

1

u/[deleted] Jun 06 '25

[deleted]

1

u/SP3NGL3R Jun 06 '25

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.

1

u/gromette Jun 06 '25

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.

13

u/webtwopointno Jun 06 '25

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

3

u/DemonSlyr007 Jun 06 '25

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.

3

u/TheDifficultLime Jun 06 '25

Maybe you need to go check beach house prices..

2

u/DemonSlyr007 Jun 06 '25

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.

2

u/webtwopointno Jun 06 '25

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.

2

u/GhostofBeowulf Jun 07 '25

er care to back that up?

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

1

u/webtwopointno Jun 07 '25

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

3

u/CogentCogitations Jun 06 '25

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.

2

u/Anfins Jun 06 '25

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.

1

u/ResearchNo5041 Jun 06 '25

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

2

u/Unusual-External4230 Jun 06 '25

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.

2

u/BootsAndBeards Jun 06 '25

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

2

u/sump_daddy Jun 06 '25

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.

2

u/sdave001 Jun 06 '25

People want BIGGER houses, not better.

2

u/mosquem Jun 06 '25

Outer Banks isn’t that expensive.

1

u/Gottadollamate Jun 06 '25

Ocean front property, in Texas.

1

u/YeshuasBananaHammock Jun 06 '25

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

2

u/ResearchNo5041 Jun 06 '25

Just where I want to be!

1

u/Llanite Jun 06 '25

Well, expensive neighborhood near other rich houses, sure.

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

1

u/FTownRoad Jun 06 '25

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

1

u/Educational-Win-1803 Jun 07 '25

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.

1

u/Sabard Jun 06 '25

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.

12

u/maidenhair_fern Jun 06 '25

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

41

u/ShiftE_80 Jun 06 '25

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.

5

u/maidenhair_fern Jun 06 '25

I see, thanks!

1

u/Chief7285 Jun 06 '25

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

3

u/WilliamJamesMyers Jun 06 '25

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

5

u/SP3NGL3R Jun 06 '25

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.

2

u/FreddoMac5 Jun 06 '25

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.

1

u/SP3NGL3R Jun 06 '25

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

1

u/WilliamJamesMyers Jun 06 '25

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.

2

u/SP3NGL3R Jun 06 '25

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 :(

1

u/pgpathat Jun 06 '25

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

0

u/WallyOShay Jun 06 '25

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.

0

u/CallMeKingTurd Jun 06 '25

Yeah but that eventual expense is not the developer's problem.

1

u/[deleted] Jun 06 '25

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.

1

u/Economy-Dimension-75 Jun 06 '25

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

1

u/WorkTropes Jun 06 '25

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

1

u/TheLateThagSimmons Jun 06 '25

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.

1

u/93devil Jun 06 '25

Might sink into the ground, too.

1

u/Ok-Statistician-5242 Jun 06 '25

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.

1

u/Ok-Statistician-5242 Jun 06 '25

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.

1

u/mvigs Jun 06 '25

And salt water will still corrode concrete.

1

u/Able-Swing-6415 Jun 06 '25

How expensive is building the house twice though?

1

u/ComfortablyBalanced Jun 07 '25

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

1

u/iesharael Jun 07 '25

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

0

u/Enginerdad Jun 06 '25

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

23

u/cubgerish Jun 06 '25

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.

1

u/JerryCalzone Jun 07 '25

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.

1

u/Masky-Mask Jun 07 '25

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

27

u/Plaidfu Jun 06 '25

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

4

u/Cayke_Cooky Jun 06 '25

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.

1

u/phaskellhall Jun 06 '25

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.

5

u/becausenope Jun 06 '25

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.

5

u/PleasantStatement521 Jun 06 '25

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

4

u/Crafty-Interest-8212 Jun 06 '25

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.

2

u/747WakeTurbulance Jun 06 '25

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.

2

u/footdragon Jun 06 '25

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.

2

u/starvetheplatypus Jun 06 '25

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

2

u/m240b1991 Jun 07 '25

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

1

u/Asleep_Frosting_6627 Jun 06 '25

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…

1

u/scubascratch Jun 06 '25

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.

1

u/ranger-steven Jun 06 '25

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.

1

u/shryne Jun 06 '25

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

1

u/Strubblich Jun 06 '25

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.

1

u/HambugerBurglarizer Jun 06 '25

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

1

u/After_Way5687 Jun 06 '25

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.

1

u/qazxdrwes Jun 06 '25

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.

1

u/intheBASS Jun 06 '25

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.

1

u/kant0r Jun 06 '25

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!

1

u/Razorbackalpha Jun 06 '25

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

1

u/Level_Traffic3344 Jun 07 '25

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

1

u/namdor Jun 07 '25

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. 

1

u/Schwatvoogel Jun 06 '25

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 Jun 06 '25

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

0

u/nicknick1584 Jun 06 '25

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 Jun 06 '25

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.