Why is it so dangerous for underground bunkers to be made from shipping containers?
I bet you were thinking that I was about to give you plans about how you should dig a hole for a cheap underground bunker with a door to be used for a simple SHTF/TEOTWAWKI survival bunker. Well, you’re wrong. What I’m here to tell you is that if you listen to pretty much all of the bullshit advice on the web, that you’ll be wrong. Not like I haven’t said that before.
Shipping containers were built to be stacked. They’re called Intermodal Freight Containers because they can be moved on trains, boats, helicopters, whatever. They are meant to be large portable closets. They were not to be buried or cut into, and certainly weren’t designed to be used as underground bunkers. Once you do that, you start changing their effectiveness. They are not built for lateral pressure and not designed for long-term wetness or acidic/caustic soil. I spent quite a lot of time in Iraq and saw some of the buried shelters that were only underground partway, and they were all buckling under the pressure. Guarantee they aren’t still safe even today.
Just for reference, a cubic yard of dirt weighs somewhere between a ton and 2700 pounds or so. Imagine how much pressure a buried container bunker must have to withstand and then realize that the whole thing is surrounded by metal that’s only about as thick as a saw blade.
If you’ve never studied mechanical engineering, you need to understand that something that can withstand a LOT of pressure on one angle won’t necessarily withstand even close to that pressure at another. Think about an egg. If you push down from the top of an egg, it’ll hold up to a lot more pressure than you’d think. Press it on the sides though and it crushes before you even start pushing. Same thing for a beer can. You can stand on one with no problem but then push your finger into one of the sides and the whole thing crushes. That’s because the force pushes down on itself, which is why shipping containers can hold a lot of weight if they’re stacked.
These containers are designed to hold a LOT of weight as long as it’s held in the right spots, but anywhere else and you might as well just bury an enclosed car trailer. Take a look at what happened with this container that ended up being sent to auction.
Why? It’s physics, baby! Go to college and learn why. I’m just here to tell you that it happens, even though you may not have heard about it. Start vetting your sources before you listen to them and you’ll start seeing a pattern, and then you’ll start seeing which stories are true and which are just fluff to get you to click on their links. If you want a decent beginning to the design and capabilities of shipping container structures, check out this book.
The biggest lesson you need to learn is that if you’re gonna build an underground shelter, you need to have a building inspector come in and take it all into consideration. If you have electricity running through it, have an electrician check it all out. Why on Earth would you try to save a few hundred bucks to risk it caving in on your family or electrocuting your kid to death during the first rainstorm? Are you a really a prepper?
Other reasons why you may want to rethink burying a shipping container – or underground shelters altogether
WTF are you trying to accomplish? Sure, you can get a shipping container for a few thousand dollars. Those few thousand dollars buy you a very small room. A room that I’ve lived in for many, many, many months overseas in different combat zones. They’re called Containerized Living Units (CLU’s) or Containerized Housing Units (CHU’s). I used them just to sleep in, along with anywhere from one to three roommates and I gotta tell you, it’s not fun. I couldn’t imagine being stuck in one of them with other people for months at a time.
A shipping container is pretty much a rectangular metal tent. Imagine living in an underground bunker for months before coming up. If you’ve never spent weeks living out of a tent at night, you have no idea what it’d be like living in a bunker for months, both day and night. That’s not even counting the actual logistics of not leaving the container, including human waste, trash, emotional pressure and the actual tactics involved. I’ll be visiting the tactical idiocy of almost all underground bunkers I’ve seen in a later post but if you just think about things from the enemy’s viewpoint and how they’d attack you, you’ll either quickly see how stupid it is or you really need to just go ahead and do it now so you’re out of the gene pool before you procreate.
If you’ve ever been in combat in an urban environment, you know just how shitty of a decision it is to hole up in a room with only one entrance. One entrance means one exit. If they control the entrance, they control the exit, and they have a lot more room and supplies outside than you could have in a bunker. No matter how fortified your structure is, unless you spend a CRAPLOAD of money, all they have to do is wait you out and can easily speed up your schedule to come out.
Now I’m not saying that you shouldn’t consider a fortified underground bunker at all, but if you do, just realize that you’ve shut out a lot of your capabilities such as escape, resupply and support if you don’t make a pretty extensive plan.
Not to mention the fact that shipping containers are prone to have toxic paint and chemicals in the wood, including fumigation sprays that will likely require you to replace all the wood and strip all the paint to be safe.
Enough of that for now though because there are ways to plan around these problems but I wanted to mention them because people who are drawn to burying shipping container bunkers are the same idiots who’ll not consider what I’ve mentioned already, let alone the tactical disadvantage of being buried in a box a few feet below the surface with limited air supply and exits. I may go into the tactical ways to design and protect an underground bunker in a later thing but at the moment, I just want you to realize that if you’re going by what you’ve most likely been reading in some pretty popular articles about burying shipping containers, that you’re probably wrong.
The plain and simple truth is that a shipping container is designed to be stacked and have pretty much zero horizontal external pressure. Burying it will add a LOT of side pressure, especially if you’re in a rain-prone environment or have certain soils. They’re just not built for that. Might as well just build a frame and fill it with cement in the walls for a lot cheaper.
If you’re gonna use a shipping container bunker as an underground shelter, realize that it’s most likely made out of Corten Steel. Pretty decent stuff as long as it doesn’t get scratched and dented. If it does, it’ll start rusting through. Not a good thing if you’re 10 feet underground. They are pretty cheap and have their place in your plans if you’re smart. Here’s an example of one I found on Amazon for $2500:
As long as it’s sealed, you can make it useable if you spend some time reinforcing the walls, depending on the soil and rainfall in the area. Just make sure that you don’t bury a 9-ish foot container under 6 feet of earth in an area that has a water table 12 feet under the ground. If you want to see some common specifications of shipping containers, check out this wikipedia article.
Basically, a shipping container is pretty good for above-ground fortification as long as you fix any chemical problem. You can decide to bury one (or more) but to do it properly (not even counting the tactics and other considerations), you’ll have to spend a lot more money to make it right than just buying and delivering the containers. Remember though, just because it’s metal doesn’t make it bullet-proof (one big advantage to an underground bunker) Don’t take my word for it, do some research specifically looking at the limitations and dangers of burying shipping containers for yourself instead of just looking at the cost savings.
Structurally, pipes are MUCH better at withstanding pressure, from any direction. The problem is that they’re round and we like our stuff to be on flat floors with flat walls. If, however, you could put a rectangular shipping container into a cylindrical pipe underground, you’d be set structurally. You’d still have to deal with the fact that you’re buried underground though. Here’s a video of an example of one made out of metal:
So what should you do if you really want an underground bunker using these metal boxes?
Think it through. Have someone come take a look at your plans before you commit. Don’t be an idiot. A shipping container is a great starting point for an above-ground shelter or if you’re planning on adding a supporting structure to it (provided you’ve figured out all the tactics of being stuck in a hole in the ground with people who might want to get you out). It just might not be the cheapest way to go if you’re planning on burying it.
The biggest thing though is that if you’re trying to use it, or anything else, as a buried defensive bunker, you’d better have a hidden exit somewhere to get out if you’re found, and should be thinking about some serious camouflage around it for your entrance and vents. It would suck to spend all that money, planning, and time just to make yourself a ridiculously overly-complicated coffin.