Hello gang. I was wondering if anybody had thoughts on root cellars. Specifically, can I use a Connex box, as a root cellar. My thought is to bury it halfway down and then top it off with dirt. Will the metal have any problems? Does anybody know anything about this?

Depends on the soil, conexs are designed for vertical loads, they aren’t great when you have pressure from the sides.  Many folks have buried them just fine but like I said, depends on the soul.

As stated above connex were not designed to carry a load on the roof.

Here's a web site with some ideas:

https://americanpatriotsurvivalist.com/build-a-root-cellar/

You could berm a connex and put an insulated roof on it to keep out the heat but that's more expensive then it needs to be.

The $50 and up underground house book is another way to build a root seller.

https://www.amazon.com/Fifty-Dollar-Underground-House-Book/dp/0442273118

Lots of examples on youtube too, here's one example using culvert which is designed to be buried.  Obviously you could put a regular door on it instead of making it a hobbit house style:

A conex box is a good bit larger than most of the root cellars I have been in.  Ours is a small room that we enter from inside our basement.  The walls are poured concrete, and it has two 4" vents.  It is located under our side porch.  The floor is crushed stone, and we have a few plastic pallets in there to keep the vegetable off of the ground.  Ours is about 8' x 12'.  We don't keep that much in it, potatoes, pumpkins, squash, onions.  We tend to can or freeze most of our home grown produce. If we have a lot of potatoes, we may put a gaylord bin in there to dump them in on one of the pallets.

A few things to remember about conex boxes, they are designed to support their weight from their corners, they are not strong on the top or on the sides.  They also need to be and stay level or the doors will bind.  If you do reinforce one and bury it, if one corner settles, you will have issues a lot harder to fix if you can not lift and re level it easily once it is buried.  You will always have a step up into them unless you cut off the bottom door latches.  The doors on a conex box swing out.  Depending on your winters, if you get a lot of ice or snow, you may want a door to swing in instead of out or you may need to build a porch over the door.  One additional issue you will have is rust from all the humidity.  Root cellars are damp.  Produce has moisture in it, and with only the small vents on a conex (unless you add additional ventilation, and even with the added ventilation), you likely will have rust & flaking paint issues.

Conex boxes have their uses, but I think there are better ways for you to plan a root cellar.  Poured concrete walls or concrete block with a poured concrete roof would probably be most cost effective, for a long term root cellar.  

We went the concrete block and poured concrete roof route. Very happy with results.

Just be sure to let the concrete cure completely before you start storing anything on it.

As said root cellar does not need to be as big as a conex, I have a 2x2x4 potato box that works all winter till may on the north side of the cabin in what I call my cool room, (screen porch in the shade). I live in a maritime environment 35-55 November -April.

I settled on that size, with a vestibule and two doors (inner and outer) for an airlock.  Made it through the first winter perfectly even though my dirt work is not complete.  I was a little worried.  I just put shelves on the backside wall and shallow  wine shelves on teh front side, either side of the entrance.  Lotta work, but I love it.
Outer door awaiting my hardware:

Attached File

I live in town, so I wanted to keep construction to a minimum. I guess I’ll have to look into all these ideas. My thought was to bury it for 5 feet down in a hole and then build a berm around it. Thanks for the input guys

I am no longer a young man, and I don't believe you are either.  Carrying sacks or boxes of produce up and down a ladder is only going to get more difficult as we continue to age.  

Is there a dirt bank you can build into?  Is there a place where you could build an artificial dirt bank - think something that looks like a sand mound if you are trying to be somewhat discrete.  This would also help to shed water as long as you allow a lower area for it to drain.  Adding a little drain tile below the stone floor to a lower area would be the easiest was to keep standing water from in the root cellar.  Is there a way you could build a ramp down a few feet (at least wheel barrow width) to enter the root cellar?  If you had to, could you reduce the depth of the cellar, and spray foam the roof and outside top 4 feet of block and than cover with dirt?  Could you place the shed up against the dirt bank, and start the ramp in the shed?  How are you planning on venting the root cellar?  No vent will lead to excess moisture, leading to spoilage and mold, but vents are easy to see.  I have no experience, but I would guess that they may show up on thermal due to the temperature difference if someone was looking at night.  If they were vented in a bush that would probably help.

Keeping standing water out of the root cellar is easy, just give it a place to go.  Depth will prevent freezing, insulation will reduce the depth.  I really think long term your issue will be access.  You want this to be easy to get in and out of with bulky produce, and it would be nice if you could do it without falling down a ladder - you might damage the produce.

I guess a lot of this depends on just how discrete you want the root cellar and access to it to be.

Being that distance, with the limited acreage, I find myself wondering (if it was mine) how much time I would choose to spend up there.  5 to 6 hours travel time in good traveling conditions seems far for that amount of acreage.  Not spending much time there will increase the chances of vandalism.  

You might want to consider a stone or dirt floor in the shed if you are planning on hiding the door rather than concrete due to vandalism concerns.  Some type of stone would be easy to rake away and back over the opening.  You may want to consider also storing some prepackaged food rather than just veggies if you are planning to bug in to this location.  Based on the location, I wold think it gets cold there in the winter.  I assume you are traveling in an RV of some sort and not planning on living in the shed.  If living in the shed, insulation and heat would be necessary for the cold months.    If your and other families are planning to share the acre to live on, you may find that you wish there was more land.  An acre is not much, particularly if there are a number of energetic children wanting to run around.

If bringing an RV, could you get a shed big enough to park it in?  That would hide the RV, the opening, and provide heat, cooking facilities, and restroom facilities.  It would be a really obvious and unusual shed though.

Edited to add, you are still going to have to mitigate the standing water and humidity issues in the cellar.  A closed door and limited ventilation will make that difficult in an area without electric.  That or completely seal any stored food.  Mylar in buckets or mylar in sealed PVC would be least expensive.

But hobbit style is so awesome:

hmmmm

https://www.youtube.com/watch?v=WN9DA8qGT88

Where do you get that bolt together culvert!

Not trying to sound snarky, but places that sell culvert.  I have no idea where the guy in that video got his but I know we have a place a couple of miles from where I live that sells all sorts of corrugated metal pipes, storage tanks and troughs.  I've never had any reason to stop there and never paid much attention to what they have sitting around but I'd assume they could order anything their suppliers carry.  Maybe do a search for manufacturers and see where they have distributors?    If I had my own property I'd probably either go that route or poured concrete; the chickadee guy has far more skills and especially patience than I do.

Already called local businesses and they sell solid. Found some in Canada though  no shipping

Try adding the term "nestable" to your search- it looks like that's the term they use for the pieces to make them easier to transport. Maybe hit up your local county or state road crew and ask where they buy it from?  Maybe call a civil engineering firm ot paving company?  I honestly don't know. My only hands on experience with culvert is some 24" stuff I helped my best friend put under some of the roads at his farm and he got that from Tractor Supply; I don't think they carry anything larger though.