How To Stack Containers
Containers are great for stacking. They are like adult Legos to put together in combinations that fit your needs. But here are a few things to consider when planning your container stacking.*
The quality of your container. When you are stacking containers, you want to make sure the bottom container(s) are structurally sound enough to handle stacking. Generally speaking wind- and water-tight containers, cargo-worthy and one-trip containers will all be fine for stacking. For cargo-worthy and one-trip containers, you can stack them 9 high. For wind- and water-tight containers, you will want to inspect the sub-flooring and corner posts to make sure that they have not been damaged or worn out.
Corner-post to Corner-post. Containers are designed for stacking on ships. On ships they stack like-sized containers one right on top of another, lining up corner-post to corner-post. If you look carefully, you’ll see that the corner-posts sit just a little lower than the bottom of the container and just a little higher than the top of the container. The corner-posts and flooring of the container are designed to bear the weight of the container and the container(s) above it. So you want to do the same with your stacking. If you are stacking 2x20’ containers and 1x40’ container, be sure that the 20’s are on the bottom so all four corner-posts of the 40’ container have corner-posts to set on. If you do the reverse, the 20’ corner-posts will not have proper support and the 20’s could fall through the roof of the 40’. If your design does not allow for this, then just build in supports for the corner-posts.
Locking containers together. When containers are loaded on ships, they are lashed together. This prevents containers from slipping around on the ocean. If you want to create more stability for your stacked containers, you can get these twist locks to lock your containers together as well. They are a minor investment for a big peace of mind.
The actual stacking. So the plans are nice, but how do you DO it? Generally speaking, you will need a forklift or crane to set the containers in place. The trucks that set containers down cannot stack them. They simply slide the container off the truck, so they cannot stack. Some forklifts can pick up containers. Container forklifts pick them up from above and can handle 20’s and 40’s. Forklifts that operate with forks need to be checked for a few details:*
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The forklift pockets on 20' containers are 69" from the inside of one pocket to the inside of the other pocket. The forklift needs to be able to spread that far apart.
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If the forklift cannot manage that, then the forks (or fork extensions) need to be at least 8' long so the forklift can pick the container up from underneath. But if the forks are not long enough, they will poke through the floor of the container.
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40' containers generally do not have forklift pockets, so you will need 8' long forks to pick them up.
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20' containers weigh 5,000 pounds and 40’s weigh just shy of 10,000 pounds, so forklifts need to be able to handle that kind of weight.
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As in all larger projects, you want to have someone familiar with the limitations of the forklift inspect the project before starting any work. They need to make sure other factors are being addressed (level ground, other environmental concerns, etc) to be sure that everything goes safely and smoothly.
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If your forklift cannot handle the project, you may have to hire a crane to stack the container. Our recommendation is to find the closest crane and material handling company to the site to help you out as they generally charge for travel, set-up and work time. They can help you find the right equipment to handle the job.
Have fun! Be safe! Start stacking!
*Super Cubes does not take responsibility for the safety of projects like this. These are meant as guidelines, not an exhaustive list of things to consider before taking on a project like this. But hopefully, this has helped you with the initial planning stages of your project.