Letter Re: Questions on Underground CONEXes

Hello Mr. Rawles
I’m a fairly new reader of your site and have been meandering through your archives and checking back periodically. It’s a wonderful site you have here, and I’ve found your articles to be quite interesting and informative. My personal concerns for the future are more focused on nuclear events than fiscal ones, but in either case I’m likely screwed as I am living on the east coast in close proximity to dense population centers and terrorist/military targets.

As of late however I have been considering buying a few acres in one of the rural areas a few hours away. Someplace where I could build a small cottage to go and relax every now and then. Perhaps with a few unobtrusive modifications to make it a bit more disaster resistant. But I want to do something that’s both low budget and low visibility. Especially since I hope to move away from this area in the years to come, and don’t want to spend a fortune setting up something I’ll be a thousand miles away from in times of trouble. (Or trying to sell a place with expensive hidden features I don’t want to mention publicly… I believe you just commented about that issue today.)

To that end I’ve been pondering the pros and cons of buried cargo containers, and I was wondering if you know of anyone who has done any serious engineering studies of them? I’ve read a lot of speculation about them, but very little hard data. Obviously they’re quite strong and stackable, but only along the corner posts. I haven’t ready any serious studies of what kind of lateral force they can withstand, or what kind of internal or external reinforcement might be necessary to berm or bury. I’ve heard suggestions about flipping the containers over, since the floor is designed to support a massive load. But it seems to me that if you flip it over, the load is now on the wrong side of the floor supports. A system to carry the load on the corner posts should work, just like the floor of each stacked container does. But cutting the bottom off of one container to use as the roof support of another seems wasteful and inefficient. And I’m not sure what kind force would be applied to the sides of a buried container or how much pressure corrugated steel can withstand.

Personally I was considering burying two twenty foot cargo containers side by side. At eight feet or so wide, that equals around 320 square feet of storage and living space and produces a pretty square footprint. Bury them under three feet of earth and you have a decent fallout shelter with space for a significant amount of supplies. Presuming it’s not going to collapse under the weight above it. And that it is properly ventilated. And hasn’t filled with water or condensation.

Now here is a second item I was hoping you could offer some advice on. If I do build something like this, I want it to remain a secret. I am assuming that with a bit of training, a bit of rental equipment, and a lot of elbow grease, I should be able to excavate my own pit and even drag a cargo container or two into it without killing myself. But what if the structure does require some additional support in the form of a concrete shell or load bearing roof? It would be a significant volume of concrete. Far more than one man and a few friends could possibly mix and pour. Which would mean hiring a cement truck. And a load of cement workers curious as to what the h*ll you’re building in a hole in the ground.

So, any advice on how to have work such as that done without worrying about every concrete worker on the crew showing up on your doorstep in bad times, families in tow? Aside from avoiding outside labor in the first place? This, of course, applies to any sort of expert service you can’t possibly handle on your own.

I was also considering how to ensure proper ventilation, and how to camouflage the vents. Here is a thought that may prove useful to some of your other readers who are considering similar projects: It might be possible to hide the air intakes in plain sight. A lot of passive heating and cooling systems are becoming popular these days, and one such system is earth cooled tubes. An earth cooled tube is pretty much what the name says: A length of tube buried a few feet underground, where the temperature is fairly stable. By blowing air through the tube you can cool it in the summer and warm it in the winter. I’m not sure how cost effective it actually is, since you still need a fan to blow air through the system and it’s efficiency depends on the local climate, but it hardly matters. You can simply claim that you have such a system, and that your bunker vent pipe is the intake for it. You could even pass it off as a reason not to dig or build over your bunker, since that’s where your ‘passive cooling system’ is buried.

Or alternatively you could actually install such a system and route it through the bunker, keeping it well ventilated as you cool or heat your house. Mind you, there may be moisture and condensation issues you would have to take care of. But if you do need to make use of your bunker it might help keep the living conditions inside it a bit more bearable.

Anyway, I believe this e-mail has rambled on long enough. I’d appreciate any advice you can offer, and I wish you and your site the best of luck. Keep up the good work! – Robert in New York

JWR Replies: I’ve seen precious little hard data and lots of speculation about using CONEXes underground. One thing is certain: “as-is” they are not designed to take a substantial load anywhere but the corners. Since I’m not a structural engineer, perhaps a reader that has some “in the ground” experience can fill us in on what sort of internal or external support is required to make CONEXes safe for use underground.