Recently, I completed a paper and a presentation at Columbia University for the use of shipping containers for modular buildings. Here is my presentation that I prepared. It’s about 45 minutes long, and covers the history of modular buildings briefly, the history of containerized shipping, and how shipping containers have been used for a faster and lower cost way of building.
If I had to say what was the best project I have ever worked on as an engineer in the 33 years since I graduated from the University of Maryland, it has to be the shipping container apartment building on 3305 7th Street in Washington, DC. It was a rather unusual project in how it started as far as I was concerned. I was working on a job in New York, and I stopped in Washington, DC to visit my sister on my way home. While I was at my sister’s house, I got a call from a DC area code on my cell phone, so I went ahead and answered it – normally I don’t answer my cell phone when I am visiting people, but this seemed a bit different. The call was from Kelly Davies at Travis Price Architects. She had a shipping container building project that had an investor, and a contractor. Her firm was an established architecture firm in Washington, DC. Was I interested? Of course, and not only was I interested, I could meet with her that afternoon, since I just happened to be in the area.
We met in a conference room in the Acela Lounge in Union Station, and the meeting went very well. Travis Price came in and joined us, and we came to a preliminary agreement. A couple days later I had the contract and we began design. Since DC is fairly easy to get to from here in Atlanta, I went up to work in their office a couple of times. The design basically started in April, the house was permitted, and finished by October. For this size and complexity of a project I have never seen it done this fast. I’ve seen permitting take longer than this. Of course it took some very fast reaction times. One morning I was in Binghamton, NY waiting on the bus to New York City, and I got a frantic e-mail needing some sort of letter from me. I wrote the thing in the waiting room of the bus station and sent it back before I got on the bus ( I really, really hate airports so I will do anything to avoid flying, even if it means riding a bus – which is actually kind of fun ).
What amazed me is the publicity we got. The project got on page one of the Washington Post on the day the containers came in. We were featured on news outlets all over DC and covered nationally. Not all the reviews are positive for this project, which is expected. Many are ignorant – like comparing shipping containers to house trailers. Structurally this building is very stout and I thin has a life span of about 200 years. Others didn’t like the look, and aesthetics are a matter of personal taste. Others felt it somehow was wrong to live in a box originally designed for shipping goods. In such case, you don’t have to live there.
Anyway, here are pictures of the final product taken by a professional photographer:
Sometimes when you build a project the story behind it is interesting in itself. Right now I am sitting in a camp chair on 7th Street in Washington, DC writing this post. We’re putting up the second floor of this three story apartment building near Catholic University. How did this happen? It starts out with Matt Grace and Sean Joiner. Both are Catholic University graduates; who began investing in real estate around the university. They bought homes and rented out to students. The house at this address was in pretty sad shape, so continuing to fix it was not a great idea. It had cracked foundations and many other problems.
As luck would have it, Matt’s girlfriend, Kelly Davies, is an architect who works for Travis Price Architecture. Travis is a well known architect in DC and he frequently lectures at Catholic University, and makes yearly trips to Ireland for various projects. Matt met with Travis, and after some discussion the idea of shipping containers came up. Kelly started the design work and began searching for a structural engineer that does shipping containers. Kelly found me on the web, and gave me a call. As luck would have it, I was visiting my sister in the DC area, so we met about an hour later. This I believe was back in April. I began my design work immediately.
This project, like most container projects required a lot of back and forth work between myself and the architect. When I could work it in my schedule I went to Kelly’s office in Georgetown and worked there. My first iteration was rather expensive, but I didn’t get “do we really have to do this?” (I hate that question) Instead, I got – “what if we do this? ” We developed a number of cost saving innovations in the process.
One of the days I was at Kelly’s office we were discussing who should be the contractor to do the container modifications. The company Cube Box came up, and Kelly called them. It turned out that one of their representatives was in Baltimore, and he came down to see us about an hour later. They got the contract.
I had to get my license in Washington, DC which took about 6 weeks. If I had been one day earlier with my paperwork, it would have been 2 weeks, but that’s how things work sometimes. Still, the permit application went pretty smoothly. There were minimal design comments, which we responded to immediately. Matt walked the plans through the permitting office and got the permit last week. We started yesterday and all the units should be up today. The project is to be completed by mid-August, and Kelly and Matt get married in September.
Our latest project is in Washington, DC at 3305 7th Street NE, near Catholic University. It’s a four story building made from 18 containers, it will have 8 apartments. The architect is Travis Price Architects and we are the structural engineers. The project moved extremely fast, we started design in April 2014 and by the first week of August 2014 the structural part was just about complete. The media attention has been extensive, here is a link to one of the local newscasts. We also got front page treatment from the Washington Post.
Structurally I am using the containers to do most of the work, there is very little extra structural steel added. The biggest hassle was to provide the wind bracing in the basement, I have some massive foundations. Here’s a couple of pictures:
I get a lot of calls and e-mails from people who want to build a container house, and unfortunately I come across as rude when I don’t mean to be. A lot of times I am called when I am really busy, and the person tries to hold me on the phone. This costs me a lot of money, which does lead to me being short to get the person off the phone. Let me go ahead and put down the issues here, and that way I can be a little less short and come across not so rude:
1. To build a container house you need these important items: A competent Architect, a Structural Engineer, a competent contractor, and funding. I will cover each one.
2. I’ll start with the last because it is the most important, funding. From my experience, banks generally won’t lend for a container building. The reasons will be obvious as we go down the list. Also, you need to figure about $150.00 a square foot, I don’t care what the other blogs say, I have been involved with building these things, just look at the pictures on my website. A lot of the people that purport to build container houses have no photos, or photos they lifted from other websites (like MINE!). Also, you need to set aside a good amount of money for architectural and engineering fees. Oddly, people call me up and argue with me on this, and try to advance negotiate me and the architect down – that’s when I get irritated, and please don’t do that to me.
People from around the world have claimed to have built the houses below. One guy even spoke to the news media in front of the houses like he was constructing them. They were not built in China, and if you see them in a recording of a newscast, the guy appearing had nothing to do with building them. None of the team involved ever was interviewed on television. Glen Donaldson is the owner/builder, James Kirkpatrick the architect, and my company did the structural engineering. Anybody else you see in the media featuring these houses was probably not involved in the construction or design:
3. You need an Architect. I mean a LICENSED Architect, not a home designer or unlicensed Architect. It will be more expensive, but you will pay less during construction. There is a lot to designing a building that a licensed Architect knows how to do, such as detailing windows, roofs, and doors. There is space layout, egress, size of windows, finishes, all that stuff that an Architect is trained to deal with. I can’t help you find an architect by the way. I used to refer people that called me to Architects I know, but after endless meetings with the potential client, it always ended up the same way – the project disappeared, probably due to item #1. This wasn’t a big problem during the Great Recession, but today meeting with you for a couple of hours on a project that probably won’t happen costs myself and the Architect money in work that isn’t done. There are a few Architects that specialize in this type of work, you can use Google to find them.
4. The contractor is the next issue. As I said in an earlier post, Bob the Builder is not the one to call. For the houses here in Atlanta, the owner built them for himself. He contracted directly with container yards to do the modifications, and he directly contracted the subs. It took a lot of work on his part, and you may have to do the same. The problem is if you intend on doing it that way, it may be hard to find a good Architect or Structural Engineer, because you will end up taking up a lot of their time. OR, you will need to budget in your fees for the time you will need to take up from the Engineer and Architect.
The problems I have had with individuals that have called me is that they have little knowledge of construction and unrealistic expectations. In every case, they were totally unprepared for the cost of the project, and had no real source of funding. They usually had no knowledge of how a project is designed and built. I have had ones that wanted to use junk they found lying around to build the buildings, one sent me pictures of some old beams he found and bought, another wanted to use some old light poles he scrounged up. You can’t do that. I’ve had people convinced they could build the houses completely for free. Others have argued with me why it was so expensive to pay me – it was “only a few hours work”. It took me 35 years of experience and more education than I care to talk about to get to that couple of hours work. I also get people that call me that know more than I do – they don’t need an Architect, they can do that, they don’t need a contractor, they can do that, and I am certainly wrong with the cost of construction. One caller went so far to tell me not only those items, but my website was no good and he could fix it for me.
So, if you want to build a container house, lets sum it up. First you need to make sure you have the money to do it. You may need to get private investors or use your own money. Please don’t expect myself or an Architect to come with you to meet potential investors. Preparing your presentation is something you have to do. You need to find a good licensed Architect. Expect to pay him or her for Construction Admin services. Find a contractor, early. This isn’t something you can bid. Then get your Structural Engineer. The Structural Engineer and contractor need to be involved in the design process from the beginning to make sure the Architect prepares a practical design. Expect the permit process to be long and drawn out because you don’t have conventional construction. You may have significant resistance from the neighbors, and this could kill you depending on the zoning in your location or the permit process. Some areas require approval by different community boards, and this could sink you.
If you can handle all of the above, you can probably do it. Again, don’t expect it to be easy. I hope I didn’t come across as rude or snippy here, it wasn’t my intention, and hopefully this answers a lot of questions.
I get asked over and over again if you can bury shipping containers. Fortunately, most people accept my answer, which is simply – no. In fact, just the other day an architect I work for sent me a question about whether a container could be buried. I answered, “no, it will crush like a beer can.” He wrote me back – “thank you George” and that that was it. I guess that since I am a licensed Professional Engineer with 35 or so years experience in construction, plus going through graduate studies in Columbia University in structural engineering convinced him that I know what I’m talking about.
Unfortunately, not all people are like that. One one site I was quoted about this matter, and the answer came back from some fool that said, “hey, they stack them like 30 high on ships, so they can be buried”. Well, do your math. A container is 9 1/2′ tall. If you stack them like 30 high, that comes out to be 285 feet high. That’s a 28 story building. Have you EVER seen a 28 story high merchant ship? A slight wind from the side would roll the thing over. OK, let’s look at how incredibly strong containers are – for STACKING! You can stand on top of a can of beer can and it will probably hold your weight (provided you aren’t too heavy). Lay the beer can on its side and stand on it. If you are stupid enough to do this experiment, do it in your living room on the carpet right after your mom cleaned it. Because if you are this stupid you probably don’t have a job and you live in your mom’s basement.
Shipping containers have very little strength from the side. They have 0.07″ thick steel on the side which is about 2 mm thick (that is the metric system for you out there that remain convinced you can bury these things). That thin steel can take a bit of a beating from the random forklift hit, or someone hitting it with a hammer. However, the pressure of soil at 9 feet deep is about 315 lbs/sf. That’s a bit high for 2 mm of steel.
Now, one idiot called me and wanted to know if he could bury a container. I told him no, its sides are too thin. He said “but it’s made of Cor-Ten steel”. Look, Cor-Ten steel is not a magical substance. It is steel that is chemically formulated to not scale when it rusts. The rust then provides a coating that protects the underlying steel, making it great for bridges and outside structures since you can save on painting them. It isn’t any stronger than any other steel.
Every now and then I get an e-mail with a link to a You Tube video where they bury a container. There usually is little commentary in the e-mail, I guess the sender figures I will watch the video and have a reaction like this:
Well, I don’t. There are all kinds of You Tube videos. So what? I. They need to do a video of that container three or four years from now when its sides have crushed in.
The next one I get is – “Well, what if I encase it in concrete?” Yes, that is an excellent idea. It will work. Here’s another idea – why not just make a concrete vault and save the hassle of the shipping container? Here in Georgia there are wall contractors that have metal forms that piece together and you can form a wall, pour it, and reuse the forms for another wall. You could hire one of these contractors and save the hassle of entombing a container. Unless you really, really like shipping containers.
I also get asked, “can’t I reinforce the container?” Yes, with a lot of steel. Or, you can pour a concrete vault. OR you can even build a vault from reinforced masonry. Both are probably a lot cheaper and easier than reinforcing a container. Also, neither will rust through. Cor-Ten steel is rust resistant, but I don’t know how well it will do in a buried environment, especially if you have corrosive type soils.
I get e-mails all the time from people that want to build their own shipping container houses. Some of them are actually quite belligerent as to why we won’t work for individual homeowners in designing these. Some plead with us to make an exception, others ask for us to point them to a builder that they can go to that we will work with. Let me explain our reasoning, and hopefully clear up some confusion.
First, we have done work for individuals in the past, and it didn’t work out well. In most cases they had unrealistic ideas as to what this type of construction would cost. If you are building a container house by yourself, I don’t care what the many other websites tell you, it will cost you about $150.00 a square foot. Now, somebody will reply to this pointing out they “know a guy” that built a house for couple hundred dollars. I’m not talking about a hermit living in a box in the woods. I’m talking about a permitted legal house . I’ve challenged people to come up with a specific house that has been permitted and follows all applicable codes that costs less – I need specifics. If I get one of these, I will happily post about it here on the website.
Second, if you’ve ever built your own house you know what a pain in the neck that it is. Shipping containers are not conventional. Cutting them requires a skilled hand with a plasma torch or diamond saw. Welding them requires a lot of tedious grinding to get rid of the epoxy paint, and a skilled hand at welding. When you cut the sides off, the containers spring out of shape. They have to be lifted by a crane. This is more commercial type work, not residential. I don’t care if you’ve built a wonderful wet bar in your basement, it’s not a DIY project. I know there are websites out there that say that they can be built as a DIY project, but there are also websites out there that say the moon landing was faked, and that the US Government has an Alien breeding program where aliens are cross bred with humans. Look, I worked for the Government, and we were too incompetent to fake a moon landing, and you would have better luck mating my parrot with my dog than a human with a species from another solar system. You also would find building your own container house only marginally easier that mating the parrot with the dog, and would have better luck faking the moon landing.
Third is the liability. “Liability” is often used as an excuse for poor service, but in this case it is real. If you contract with us to design a house for you, and you run into all kind of problems as you find it’s sprung out of shape, you can’t get the floors to match up, you have problems stacking the containers, and the details have to be changed, you may get very angry instead of realizing you waded in over your head. That’s how lawsuits begin. It’s just not worth the risk for us.
If you really want a container home, you need to find a builder that is capable of doing commercial type steel work. You also need a licensed architect. From there, feel free to have them contact me for the structural design. Understand you will pay a premium for the house – on the order of $150 a square foot, or more depending on where you live.
The Weather Channel recently did a short video on one of the shipping container houses we designed in Atlanta. Glen Donaldson the owner/builder leads the tour.
These projects in Canada are in the northern part of Saskatchewan Province and were designed for 3Twenty Solutions. 3 Twenty Solutions provides prefabricated buildings for remote sites that are used by oil companies and mining companies. These sites are inaccessible most of the year except by plane, and the only way to haul supplies up is during the winter over ice roads for many of the sites. Since it is hard to get construction equipment to these sites, and the weather is far from perfect, as much as possible must be assembled prior to transport. So, modified shipping containers fit the bill perfectly in most cases.
This question came in to me by e-mail considering shipping container structures. It is from a graduate student that is doing research on the structural design and analysis of a shipping container building, and he is working on doing it by FEM (Finite Element Method). Finite Element Method design is a very good way to model complex structures and lends itself well to computer analysis. I’d like to share my answer with you all:
——– Original Message ——–
Subject: Dry Cargo Shipping Container Structural Integrity
From: “Shane xxxxxxxxxx
Date: Tue, February 21, 2012 2:13 am
Dear Mr. Runkle,
I want to begin to thank you for taking the time for reading this email. I will try to keep short and clear.
I am a structural engineering graduate student at xxxxxxxxxx and I am involve in a multi-disciplinary team designing the next generation of innovative student housing at xxxxxx campus. The multi-disciplinary team has decided to design a high-performance sustainable green structure that will have a dome-mound of dirt as a green roof and the main structural system will be composed of repurposed shipping containers.
The reason why I am emailing you is that I was researching online about any structural analysis or finite-element analysis that has been done for dry cargo shipping container and came across your name at this website: (http://ronestudio.wordpress.com/2012/02/10/basic-container-design-structural-considerations/)
I wanted to kindly inquire if you know of any published information about the structural integrity of cutting walls and windows to dry cargo-shipping containers.
I have found several technical specification requirements from ISO that accounts for both static and dynamic loading but all are under the assumption that the load path is from the cargo floor>C-beam floor joist>Longitudinal C-beam>Corner fitting>Foundation (or the next lower shipping container column).
So far, roof-loading scenario of soil mound is 600lb/sq. ft. and ISO requires roof of shipping containers to handle 300lb/sq. ft. We are looking to reduce load by using alternative fill material but are still concern about combining 20′ shipping containers and cutting entire wall out. I have found one case study of a cabin that you advise by replacing entire wall with two 6″x3″x1/4″x19′ steel box beams welded the entire length of the containers. I believe this cabin did not have loading scenario as much as we have.
With that said, I kindly ask if you could share any information you have regarding structural integrity of a shipping container used as housing. I will be performing a finite-element model of our final design and I wanted to see what information is out there before I begin. Again, thank you for your time and I look forward to hear back from you!
Shane xxxxxxx Graduate Student
There is no published information about container strength when they are cut up, and because there is a huge number of configurations, a prescriptive type of guidance would not work. You have to break the container down into its constituent parts and model it based on the sections of the parts. I use a 3d FEM program (Bentley RAM Elements) and I have put all the parts in as sections. For the sides, I use thin steel shells. You have the following parts in a container:
1. Rear posts – these are roughly steel angles. It’s fairly simple to calculate the moment of inertia of these, or draw them in AutoCAD and let it figure the modulus with the MASSPROP command.
2. Front posts – these are fairly complex members made from two different size channel sections. The moment of inertia can be found by drawing these in AutoCAD and using the MASSPROP command.
3. Bottom Rails – these are C sections, again fairly easy to calculate section properties.
4. Top Rails – these are steel tube sections
5. Side corrugations – these can be modeled as cold formed hat sections.
6. Top corrugations – again, can be modeled as cold formed hat sections.
To get specific information on containers in the form of drawings, check out this site: http://www.isbu-info.org/
RAM Elements will automatically find all the section properties of the sections once you program them in. The side corrugations are pretty easy, you can use existing AISI hat sections. The other members take a bit of work using the LEO language that comes with the program. Also, I’ve found that it is necessary to stiffen members as you make cuts in the container. That takes again more work with the LEO language in RAM Elements to model the sections, or conversely you could calculate your section properties by hand (not recommended, too much chance of error), or a program such as AutoCAD.
You are right, the ISO testing is not applicable in any way. It assumes the containers are not cut into, and is only applicable for their use as cargo carriers. There is no way it can be used for building, although I did see it used by an engineer in his calculations. In case of a failure, it would make for an interesting lawsuit against the structural engineer, he would lose big time. I hope this helps. A copy of this e-mail is going up on my blog, with your personal information removed, since your question is very good I’d like to share it with all.
George W. Runkle III, P.E., PEng, MIEAust
Runkle Consulting, Inc.
930 New Hope Road, Suite #11-145
Lawrenceville, GA 30045