Engineering Advice (Root Cellar)

Have always been told that steel shipping containers must not be buried without internal support. I agree with that. However here is what I would like to discuss.
Suppose the seacan was used as a form for concrete, with proper temporary internal bracing which could be removed after the concrete had set and cured to first strength say minimum of 48 hrs.
The seacan would be placed inside the excavation with enough room around the exterior walls to construct a plywood form. The walls would have appropriate size footings and rebar. The roof would have I-beam of say 4 inch section and wire panel placed on top and tack welded. The I-beam extending to sit on top of the concrete walls. Then 6 inch of concrete poured for the roof. Giving 2 inch of concrete over the wire and I-beam. After the concrete had reach strength the internal framing and walers would be removed. It would have to be sealed after full cure then buried. What am I missing?

 

I've actually thought of this myself a few times . One thing I've thought about would be , prior to pouring the concrete , or placing the forms , I've thought it might be a good idea to spray all sides, tops , etc , with possibly a tar type waterproofing , which may help in preventing water condensation inside the container , , and possible rusting of the container metal in contact with the concrete . Let me know what you think of this . Another thing to seriously think about here is water intrusion from rain , water table , rain flowing down the stairs , and water coming up from under the floor , etc. This became an issue in our conex boxes placed underground in a combat AO years ago .

 

It isn't obvious to me what the advantage is to having the container remain in the concrete. Why not just form up a concrete box and go with that?

There really is no way to assure that concrete will adequately fill under the conex, and like as not support during the placement becomes an interesting problem.

 

I have met a guy who bury one, a 40 foot. What he did was dug into the side of a hill with the Container area at a slight downward angle to ensure water drained away from the hill/container. He then graveled it (which I am not sure is necessary) and placed the container. Next, he put 4"x4" supports (I think 2"x4" also) every 2-3 feet sort of like it was a tunnel which he got a mining friend to assist then he covered it up leaving the front open. The last step I can't remember if he said to ensure you bury the sides first or the top first but it was important. He then built sort of a wooded structure on the front, planted the hill with grass seed. He used it as a root cellar and apparently it work extremely well.

 

Do what we did, place two conex side by side, welded together, and install steel dividers inside each all the way to the outer walls to brace them internally! Use an EPOXY primer/sealer and back fill with gravel and sand loam! For any drainage, install french drains and run ether a catch basin, or plumb it out ether with a sump or a sump and pump depending on how much water incursion you may get! DO NOT USE CONCRETE with out first treating the steel first, the chemicals will react and the steel will not only rust, but will also eat into the concrete and weaken it as well! Most Conex are treated for sea duty with some sort of inhibitor which you need to be careful of when you weld or bury them!

 

Deepest I dig here is when building sand castles on the beach, but I grew up with basements, so I have to ask, why not just build it as you would a conventional basement. Excavate your hole, install necessary drainage and moisture barrier, pour a floor, and build reinforced block or poured walls and ceiling. If you didn't want to disturb the landscape you just start a bit deeper so you have space to add dirt on top. All the basements I knew had floor drains and I'd not waste my time building one that needed a sump pump.

Building without the restrictions of the shipping container also opens up shape, height and exit options. Looking at the weight of a couple feet of soil over a concrete slab roof would make something narrower more desirable. How about an X pattern with a vertical manhole entrance inside a garden shed for greater concealment? Or a big E layout with an extended hall in the center exiting on a hillside covered with evergreens?

 

Can you give some detail on the steel dividers. What material and spacing? How much dirt on roof etc. Thanks

 

Very nice work. I built one similar inside our old dairy building last spring. But now we are planning our move to MT. And will need a new root cellar////. The new property has a hill to dig into.

 

What did you use for chairs for the rebar, can't make it out from the pictures on construction we used plastic chairs from the concrete supply? I see you kept your rebar back from the surface of the finished concrete properly. Did you use any special mix example fiber etc.

 

My reasoning for using the seacan was utilizing it as my form work for the concrete. I am not set on that idea tho. Concrete blocks are cheap, but play heck with my 70 year old back. Especially as I get above shoulder height, worn out shoulder joints don't help. The thinking was I could remove the internal supports once the concrete cured. I was thinking if I used this method I would only need to waterproof the outer concrete shell but I need to rethink that based on your comments.

 

My ideas are not set in concrete. I love concrete but was thinking the seacan buried, as a lazy man's way to get the job done. Given my age and limitations physically. Also where the property is, it is all mountain road and not likely to get a concrete truck in there. But I do weld and maybe should explore your ideas a little further. I am thinking at lest 2 feet of overburden on the roof. But like BTP said without structural support you get a squashed can. I was thinking good slope back on the sides and gravel fill to reduce the lateral loading on the walls.

 

Brick halves.

No special mix, other than small aggregate due to the fact I had to have it pumped up to the area used (north side of my garage wall, which was below grade due to the slope of the mountain.)

 

@TnAndy Damn, Andy! I got to make sure the wife don't see this or I will never stop hearing about it!

 

I would say, in all seriousness, skip the shipping container and skip the concrete blocks, too.

Go to foam block construction, and pour the walls. That makes a nice monolithic structure. If you plan to bury the root cellar, be sure make the top strong enough to park a loaded truck on it.

You can get roof strength with a very thick slab, or with a gently arched roof.

If you go with foam block you can get the size and shape you want, and the entryway you want.

Regardless of the square footage, a square room requires less material, time, and labor than a long skinny one.

If you want to research the foam block option. Here's a demo video to start:

 

Foam block IS nice, but sorta high dollar. 8" block with rebar horizontal and vertical is pretty stout if you fill it with concrete. I poured a 6" top on mine and had my bulldozer (about 15,000lbs) parked on top when I back filled it a few month later.......figured that was the heaviest thing that would ever be up around that side of the house.

Honestly, I'd probably avoid using a shipping container for anything but shipping or dry (above ground) storage.(assuming you build a roof over it for long term)

Underground, there would be moisture issues, strength issues, and yeah, I guess all of that could be overcome, but why bother....just do it with time tested methods/materials and be done with it. By the way, a true ROOT cellar is meant to be higher humidity.....notice the gravel over dirt floor in mine. Containers have a sealed, wood floor NOT conducive to storing raw food items. A root cellar for most home needs doesn't need to be very big....mine is 10x10' approximately and that is plenty big enough. DO NOT plan to store dry things like canned goods in there if you truly build it for a ROOT cellar. Notice what's IN mine....potatoes. We also store eggs when temps allow me to keep it in the 40 degree range. (late fall to about now) Keep some stainless steel stock pots in there, plastic mop bucket, some foods in sealed plastic buckets. Shelves you can't see to the right hold plastic bottled water and Diet Coke my wife is addicted to.....she can come in from the store, open the car trunk and walk right into the cellar as the door is in the garage wall.

Build a separate, far more dry, storage location for everything you want to keep dry.


Same thing for using the fool things as housing....by the time you stud out the inside, put a roof on it, side it, insulate it, put up with the fact the vapor barrier (the steel container wall) is on the wrong side usually, the size issues (long, narrow box), WHY anyone would spend the money to convert one to living in is just plain stupid....IMHO.

 

I went the cheap and fast route after excavating the hole my self prior to the contractors pouring the cement foundation for the house! Basically I dug it all out under where the house would be built, installed the Conex's and welded them together and did the internal bracing spaced at 8 foot intervals. Then back filled and covered the roof with a foot of fill to be accessed after the contractors left. this was all done to keep things off the books and the less that knew the better!

 

I love the foam block idea, as you also get the build in insulation. But unfortunately can not get a cement truck up that mountain road. So can not go that road. Even if I set up my own batch plant, I still have no way of getting the concrete up into the forms. Thanks

OK like your thinking but want some detail. Did you seam weld them, stitch weld them, what were internal bracings made of and size, and description. Ie did you brace the walls? Did you brace the roof? etc. Thanks

Nice work TNANDY. We have 2 pantries as well for dry goods. I was trying to be subtle and call it a root cellar, it may contain more than food at the end.

 

My idea was a root cellar made from sacks filled with pumice or cinders buried five feet deep and the roof would be double, filled with insulation like this also. Black plastic could cover this whole thing. I figure Pumice is light and a 10 by 10 structure would be easy. Ocean containers are not as strong as they look.