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

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

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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

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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.

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u/bruno444 Jun 07 '25

Exactly the same in Amsterdam.

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u/plantsplantsplaaants Jun 06 '25

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

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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.

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u/PirateMore8410 Jun 06 '25

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

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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.

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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