How Exactly Are Shipping Containers Made?

A steel shipping container might seem like something simple: a box of metal that can be used to hold things for transport. Yet shipping containers are entirely different from boxes, with their own requirements and manufacturing processes (anything involving shaping steel involves some heavy, heavy machinery) and customizations. Given how vital they are to shipping (and thus the global economy), it only makes sense that they are carefully manufactured in a certain way.

Furthermore, there are so many different kinds of shipping containers that there will be variations within those container types. These require either a slightly different manufacturing process, a different assembly process (perhaps a piece is left out), or some extra steps tacked on at the end. While we will be going over some of the container types and variations, we could not possibly go over all of them. Yet without any more waiting, let us jump into the process from the first step:

From the Beginning: Sheets of Steel

Shipping containers are nearly exclusively made out of steel. Other materials might be used in small quantities depending on the type of container. Sometimes, insulated containers will include additional materials that can hold temperature better than steel (more on those variations later). Still, steel is always the baseline and always the starting point.

1. First, large steel sheets (which might be created first from larger blocks or segments of steel) are cut into smaller sheets; generally 8 feet by 3 feet (this can vary depending on the type of container, but this is the standard). These are the wall panels.

2. The wall panels are then sandblasted and corrugated. Have you ever wondered why steel shipping containers are wavy or have ridges to them? It is the corrugation, which gives the container additional durability without using additional steel.

3. Tubing is then added to this wall panel, which will be important in assembling the container later on. The tubing is welded to the floor and roof of the container.

Assembly: Walls and Floors

Steel shipping containers are not generally just punched out and sent to a port. They require assembly, and it is an integral part of the entire process, making up most of it. First, the walls and floors need to be dealt with.

4. The wall panels are set aside, and now workers start to put together the floor section (floor frame). The floor of a steel container is generally made of "I-beams." Two longer ones are used, and then smaller ones are welded between them to create the floor you might be familiar with.

Alternatively, a steel container floor might be made from a series of steel plates or sheets welded together instead. It depends on the manufacturer. More on common flooring later.

5. After the I-beams for the floor are welded together (or an alternative method), the floor frame is then sanded down. This is to make sure there are no rough patches from the welding process.

Assembly: Doors

If the doors are not solid, that leads to a whole host of problems. Their assembly is a crucial part of the construction process and an early one.

6. The doors are not like the other walls and require a (slightly) different process, if only for their size. They are cut out of the same corrugated steel but to a smaller size.

7. The doors are then encased in steel tubing and sanded smooth (once again, to remove potential rough welding spots).

8. Corner posts for the doors are then welded to I-beams. The doors are then welded inside these beams. At this point, you might say you have something resembling the shipping container you are used to, even if it still requires many panels and parts.

Adding the Roof

It is not a good idea to let the rain get onto the goods. That is why a solid roof is paramount to a quality shipping container.

9. The door frame(s) are then lowered by crane into the proper position and welded into the previously assembled and welded components.

10. Depending on the manufacturer, at this point, additional panels are craned and welded into the walls.

11. The roof panel or panels is then lowered down by a crane onto the rest of the structure and welded in, finally completing the container's full skeleton.

Painting: Looking Its Best

As you know, shipping containers usually are not the color of steel (or whatever metal they are made from.) Instead, they are painted blue, green, brown, or red. This paint serves several purposes and is an essential part of the process.

12. Now that there is a nearly complete container to work with, it is time for painting. There is usually a specific painting workshop or section of the floor, and the unfinished container is transported there, perhaps with others in the same batch.

13. A primer is applied to the container to aid with future paint coats and better protect the container from the elements. The primer is left to dry for some time.

14. After the primer is dry, the container then receives several coats of spray paint. Even more so than other items or buildings. More than one coat is used to protect the container. The harsher sea air and water might damage and corrode unprotected containers, and the containers will spend extended periods at sea.

The Wooden Flooring

Most standard shipping containers have wooden flooring in them. This needs to be installed securely and safely.

15. Wooden panels are created to fit on top of the floor frame. They might be made in the same facility or brought in from an outside manufacturer.

16. The panels are varnished to protect them from the same seawater and air that might damage the rest of the container if it did not have protection. Additionally, the varnish should protect the wood (and thus, the container and hopefully the cargo) from bugs and pests that might get in.

17. Once varnishing is complete, the panels are inserted into the container and fastened in. Screws are generally used to attach the panels to the floor beams.

Final Steps and Checks

After the wooden flooring is installed, there are still a series of final touches, checks, and categorizations that need to take place. While they may not always be in this order, all do generally take place:

17. Logos, decorations, and other decals are added to the container depending on the intended owner or manufacturer. The manufacturer could paint on them, but they could also be stickers with strong adhesives. They may also place advertisements on the container.

18. Every container has an identification code consisting of 11 characters. The code is assigned, and the container is labeled with it.

19. Door handles and any locking mechanisms are installed. These will differ depending on the type of container and the container's intended security (although they are usually standard).

20. Final waterproofing occurs, often to the container's underside, but not necessarily limited to it. Depending on the type of container, rubber seals may be installed.

21. The container is tested for structural integrity, waterproofing, and a few other metrics. If successful, the container is likely classed as finished. If not, the container is either fixed or scrapped, depending on the severity of the problem.

22. After all the above steps are completed, the container can be considered finished and shipped to its intended location (or stay in a warehouse and await shipping upon purchase).

Differences Between Manufacturers

While all of the above is accurate, you may also wish to take it with a grain of salt if you look into a specific manufacturer. They might do things differently, based on the factory layout or special features for their shipping containers, their deviations from the above can make perfect sense. Perhaps they add a special coating to the container or do things to make multiple containers in a short period. We tried to provide the average process for you.

Additionally, something to keep in mind is that manufacturing and assembly might change over time. You could automate some of these steps with the right machinery and innovation, and in the coming years, that might be precisely what happens. This could change the entire process dramatically in a short time.

Alternative Containers and Manufacturing

There may be additional or alternative steps involved depending on the type of container being manufactured. Here we hope to go over at least some of the major types and differences in manufacturing:

Here are some of the most common container types outside of the standard:

Of course, there are other types of containers not listed here, each with its own quirks and manufacturing differences. Most will follow the same standard container principles and just might have doors or walls missing or in different places. Others still might be different sizes, but in those cases, the process is the same, but different sized frames and metal sheets are used and produced. If you are curious about a specific niche container, the information is certainly available.

Additional Work and Modifications

Even after assembly, the shipping containers you might see at a port or a warehouse could undergo some additional work, depending on the job involved. Containers are used for a wide variety of products, and as such specialized containers are often used. Open-top containers are used for logs, for example, and you might more easily remove larger equipment from side-opening containers. If there is an exclusive purpose in mind, it might be possible that there are modifications (or at least labeling) to reflect that.

Method of shipment also matters. Most shipping containers are expected to go to sea at some point in their lifetime. However, some might not, and instead be destined for a life on the rails.

For shipping containers used for more creative or innovative purposes, there are additional add-ons and customizations you might make. A steel container used as an office can have windows installed or a door automatically set in. Common uses for these types of containers include:

The possibilities are endless.

While some people customize their containers after getting them, either hiring contractors or doing the work themselves if they are handy, some companies may sell the containers pre-made for these purposes. Whether the manufacturer or a separate seller does the customization depends on the company.


How the shipping containers that shape your life and business (whether directly or indirectly) are made is a fascinating subject. On a more professional level, understanding the process by which one is made can help you differentiate between containers, know which container you might need, and spot a faulty container before it becomes a problem. Whatever your reason for reading this, we hope that the information here has helped you and stimulated further interest in the subject.