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Using Pier Footings for Your Shipping Container Home

augerCaveat: before you read the main part of this post, please note that this would be my approach to things. That means what you are about to read is all opinion from personal experience. I get a lot of visitors who are owner-builder types like me, so I figured I would create this post to help some of you out there. You can do things the way you wish and use your own approach; so please don’t contact me with issues or problems or accidents resulting from your own incompetence, lack of knowledge or skill level, or equipment failure. I don’t want you to hurt or kill yourself, so be smart! You can easily create a situation where you can get seriously injured or die when working with things as heavy as shipping containers. Just use common sense and safe building practices… and if you are not sure of yourself, just hire a professional, they are everywhere. Use this information at your own risk and responsibility. OK, with that said…

If you are an owner-builder, you have a few options when it comes to a foundation: concrete slab on grade, crawlspace, full basement, or pier footings. My favorite? Definitely, the pier footings. I am speaking from the standpoint of the do-it-yourself perspective and cost. The pier foundation requires less concrete, less digging and doesn’t take a lot of tools and equipment to get the job done. Having the same benefits as the basement and crawlspace foundations, the pier footings gives you the freedom to get under the container for modifications and repairs.

One thing to keep in mind is that you don’t want any moisture underneath the container home, so you have to seal the bottom and insulate it as well. Placing the home directly on dirt or on a slab could facilitate corrosion. Moisture is the enemy of container homes. Seal, coat and avoid moisture where possible.

So how to make those big, deep holes in the ground? You don’t want to use a shovel–that’s too much work and isn’t as precise. You really want to get your hands on an auger. Preferably a two-man gas-powered auger. If you are capable of getting a hold of heavy machinery, then go for that–but its rather expensive to rent and I hope you don’t screw something up on it or you will be responsible for some costly repairs.

After you get the holes bored out of the earth, you will want to employ some forms (huge preform tubes or made from pieces of plywood) in order to precisely pour the proper amount of concrete. As for rebar (reinforcing bar), you definitely want to get those into the forms before you pour the cement in order to reinforce the concrete and add greater load-bearing strength.

You will need some heavy gauge flat metal plates (at least 1/4″ thick) to set into the cement, letting the concrete cure solidly around the base of the plates; leaving the top part of the plate uncovered and exposed to air. You will be setting the container corner directly on top of the plate, so keep it flush and level. The underside of the plates will need some arms or support bars welded to them. In the past, while working on some pier footings for some outside structures, I had cut some 1/2 inch rebar about a foot long and welded four of them to the underside of some 8×8 plates–this worked beautifully.

Note: with any foundation job, one of the biggest “oops” moments could result from not keeping each footing level with one other because you rushed or just didn’t think about that facet of your build. Talk about a goof that is hard to fix properly! There are methods and instruments to ensure you have a level foundation, just Google them and please use them. You don’t want a crooked platform for your container home. The image below shows one technique with a string run across a series of footings. Another thing, if you are working with an inspector because you are in one of those jurisdictions, you can’t get ahead of yourself. Be sure you let them see every stage of what you are doing so that they can approve it for the next stage of your construction.

After your footings have cured properly, the main load-bearing corners of the container(s) sit on top of the plates and are then welded in place. Don’t weld the container(s) to the plates until you are positive you have things positioned right! Grinding off welds is a bitch if you have never done it–it sucks.

If the footings, even after you took the time to get things right, happen to not be level, you can possibly weld additional plates to the embedded plates to create more elevation BEFORE you set the container(s) on top. You can check for level several times before setting the container(s) to ensure you haven’t goofed up. OK, that’s about it. Be careful and stay alert!

pier forms from plywood

pier forms from plywood

footing tube with rebar inside

footing tube with rebar inside

17 comments to Using Pier Footings for Your Shipping Container Home

  • hi, saw your blog and will visit again. i’m now going for a container house and will publish progress.
    God bless
    Gabriel

  • terry

    awesome..when I’m ready to excavate…I’ll document(photo and video)my work and post it.

  • Damon

    Wow! You came like a beacon out of the darkness. I’m about to build a container home in Colorado, and wanted to use piers, but wasn’t sure if that would work as I was planning. Thanks for the tips.

  • hatsukanezumi@o2.pl

    Hi,
    Which type of foundation would be the best for 1 store building made of 3×40′ in temperate climate (temp. range from -20C to 35C). I like the pier idea, but doesn’t it need some extra insulation under the house? Any ideas how to insulate and paint the underneath?

  • Terry

    Hatsukanezumi: As for the insulation beneath the store, I am thinking you can create a berm around the entire structure with native dirt (alternatively, use anything like plywood or metal sheeting first and then the dirt), preventing a draft or cold air from getting beneath the store. Yes, I would buy rolls of insulation and secure it underneath the structure as well–strapping it with bundling wire or twine should work very well. Hope this helps.

  • BobVM

    Is there a good reference on how deep the foundation should be? Of course looking at the pic above with tubing, there are several dimensions: depth of the hole, width of hole, depth of cement. The pic with plywood shaped footings seems to be either covered up in the ground or narrower. Is depth the main criteria? This is for a cold environment.

  • BobVM

    How did you set the preform tube in the hole? Did you first pour the bottom part, let it dry, then place the tube on top and do a second pour of concrete? or is the tube somehow resting on pieces of wood or bars under the surface of the concrete?

  • Terry

    BobVM: About the foundation. Typically, you can get some depth specs for your region based on the weather variables, takes a little hunting. I don’t have any data handy. When it comes to a solid foundation, you can never go overboard, but you can under-do-it.

    Here are some links on installing footings, but uses different types; just gather useful information that would apply to your situation:

    http://www.extremehowto.com/xh/article.asp?article_id=60349

    Some footing plans for different climates

  • BobVM

    What if you work with 40 ft. containers on pier footings, and you cut part of the side of the wall out? Do you think it’s fairly necessary to put at least one pier footing in the middle of the container? I mean if you didn’t would you get a sagging bounce, or not?

  • Terry

    The shipping container is extremely strong and yes, there can be a sag and that “bounce” you are talking about if say, you got 4 people walking forcefully at the same time over the middle of the container, but it’s not a seismic event. I wouldn’t worry about it. You can never do too much, so if a pier footing is preferred in the middle, I would go for it if I were you so that you don’t regret it later, since it’s virtually impossible once the container is set down. Alignment has to be as perfect as can be so that when the container comes down onto the pier posts, you wont have to shim it too much, if at all.

  • willie

    hi. i need some floorplans for conhouse. do you know of any free downloads?

  • Mr Harbert

    I am going to build a container home in Georgia. What kind of problems will I have getting permits? Do they see this like a mobile home which needs grandfathering?

    How does container homes fit in with property taxes? Do they see it as a permanent site, which they tax the same as other traditional homes, or cheaper? Is there a way that if it were made mobile that they coudn’t tax it?

    One more question please. I haven’t seen many articles about what to do about the roofs? Since it was already an outdoor box, do I still need to build a roof? If so, how and what kind? Thanks so much

  • Uncle Billy

    If possible when you use concrete, use crushed slag from a steel furnace near you as part of your aggregate mix. There are many furnaces in the US and can be found by searching “Slag” or “Crushed slag”. Its use in concrete was approved years ago by every agency imaginable. It helps recycle some of the waste we generate and is extremely strong as an aggregate. I speak from experience. Also, and this sounds odd, if you add white glue (Elmer’s-type) in concrete it will leave a very smooth, glossy and durable finish when troweled. Obviously not for walkways. But it does add strength and is useful in repairs as well. To make an effective patch paint a 50:50 mix of water:Elmer’s (you can buy it by the gallon) onto the surface to be repaired and allow to at least semi-dry. Add a small amount of Elmer’s as liquid to your patching material. Now trowel it in. Shape or finish trowel as normal. It will be very hard after it dries.

    Back to the aggregate – it works great as a drive instead of gravel. It is non-toxic and very durable. It saves rock from being quarried and helps us stay green.

  • Ian

    About how many piers would you need for two story container building?
    ie. (4) 40ft. containers side by side two high.

  • Keith

    QUESTION…
    Hi, really please i found your site, im getting ready to but a 2x40ft container home here in Japan (im English though). The land i am building on is settled and not clay but it does have a 5degree slope.
    I have brought a laser measure and im looking at 9 piers from 12 inchs above ground to about 50inch.

    Any advice any1 can offer with regard to sloping land and number of piers would be great.

    Many thanks
    Keith

  • George

    How did welding the container corners work out? I am using 1-1/2″ x 2′ ajustable anchor bolts in the piers.Setteling always happens, and with ajustable bolts, you can raise and lower container forever.

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