Recent trends in “green” building pushed experts all around the world to discover new and improved building methods. A popular method introduced more heavily in the last 5-10 years has brought more attention than any alike; Shipping/Cargo container design. These containers are giving professionals the opportunity to reuse steel, which is the most trusted building material in the world. There are many good and bad aspects to building a structure out of shipping containers, we are going to cover the typical life of a container, structural integrity, and design challenges you may face when using these. At PSE Consulting Engineers, Inc., we will also cover the best and worst ways to utilize them, based upon efficiency, costs, etc…
The life of a Shipping/Cargo Container
As you would assume containers are designed for a long life at sea. Unfortunately, most will end up taking a one-way trip to their destination and then end up stored in container yards throughout the world. Because of trade deficits around the world, it usually will cost more to have the container shipped back vs leaving it and building a new one. This is the main contributor to the quantity of unused containers that are available.
Structural Integrity
Shipping/Cargo containers are built to be very sturdy. A steel frame is welded together, corrugated Corten steel is placed on the outside of the frame providing an exterior that can withstand everything thrown at it; wood flooring is then treated and bolted down inside. Containers are designed for the corners to bear all loads, which allows them to be very strong and have the ability to be stacked up to sometimes 9 containers high.
– Steel
Containers are built out of high quality steel that was produced in a factory of highly qualified professionals such as metallurgists, engineers and technicians. Variation in steel yield and strength is very small due to the procedures and methods used in producing this fine material. Steel members are connected via welding, rather that nails that are used in the timber/wood industry for example, this provides a much stronger and sustainable connection.
– Preparation
Preparing a container for rigorous ocean travel takes a lot of work. After built, containers will be able to be loaded with up to 59,130 lbs of goods, which is a live load of 185 lbs/sqft. They will face seismic forces that are several times larger than that of the strongest seismic force recorded in the U.S. After containers are fabricated they will face the stringent code 1496 of the International Organization for Standardization (ISO). Not only are these containers tested after they are built, but they are tested again right before use and again when they are in use. The third test will include the high loads produced from the container being filled with goods. No other traditional building types have to be tested and approved twice before given a certificate of occupancy, solidifying that each and every container has consistent structural integrity at all times.
– Pesticides & Other Protection
Before you go living in one of these containers, take into consideration that the floor and other elements of most containers are treated with a very strong pesticide. This pesticide is used to shield the container and its contents from rodents or other pests that may harm it or the goods inside, as well as eliminate the spreading of diseases. It is very recommended that before purchasing a container, you research reputable manufacturers or sellers that will take the necessary precautions to ensure that your container has been rid of these pesticides.
Building with Containers
Shipping/Cargo container design is not taught in colleges or universities. Because of this, many professionals or building officials are hesitant to approve projects that incorporate them. However, there are many professionals and companies that have a vast amount of experience working with container structures. They understand that container structures, if designed and constructed correctly, are actually very safe, strong, and can be used for a variety of applications. They have been used all over the world for residential homes, apartment complexes, commercial projects, office buildings, malls, schools and much more. Also, they are used heavily by our military and companies in the oil industry.
Design challenges
Containers structures from an architectural standpoint, can be lacking if you were to keep the original shape and boring exterior appeal. Shipping containers are large rectangles, which keeps your overall layout pretty square and straight on the outside. Creating a structure with these can be a lot like building with Lego’s. When it comes to home design, many people are wanting an open floor plan. To accomplish this, you will need a great design team and fabricator. Any open space created by connecting and cutting multiple containers, will need some support beams throughout that space to help maintain structural integrity. If you are looking to match the exterior of your structure or home with the surrounding buildings, this would require adding siding of some sort over the corrugated steel siding. Another reason most Architects stray away from these projects is the fact that there are only 2 sizes of containers, 8ft x 40ft and 8ft x 20ft. Having predetermined material sizes can restrain a designer and make it difficult to add a custom touch to the building or home.
Efficient Vs Trendy
Designing a container structure usually requires modification to the container to install windows, doors, other openings, insulation, etc… This is where it can get a bit tricky; being sure to have a simple design and to maintain the containers structural integrity is the most important aspect of design. You may come across some custom homes on the internet designed out of shipping containers that do not look simple at all. They have a great open floor plan, architectural presence, cantilevered containers, and large windows all over. These homes can be very costly to build, and can increase the construction time significantly. Every cut that goes into a container lowers the overall structural integrity and it must be fabricated back to strength, leading to higher construction costs that will be much higher than a similar structure using wood or other steel. The most efficient way to utilize these containers into your design is to keep the cutting and openings to a minimum. This will ensure that you can keep your construction costs low and it will justify using shipping containers, rather than other traditional building materials. Remember to team up with creative professionals, such as PSE Consulting Engineers, Inc. and request a free quote. Our team will assist in the design and modification of your container home, they will make sure to meet your design needs with efficiency in mind.
Additional References
Our President and Principal Engineer; Nabil Taha has personally published letters directly to building officials explaining the positives of building with shipping/cargo containers. Read his Dear Building Officials letter to learn a more about the technical/professional approach to utilizing containers. Also see his Introduction to Shipping/Cargo container use in Residential and Commercial projects article