How to reinforce a shipping container home
- By: Ashley Saunders
- August 2021
Building a shipping container house is a superb way to create a unique home without spending a fortune. But unless you like living in the dark, you’ll need to learn how to reinforce a shipping container home to allow you to add doors, windows or bury them underground as a shelter.
As a giant steel box, they are designed for maximum durability yet even removing a tiny square of a side panel can weaken the structural integrity, making it necessary to reinforce it. You might wonder what’s the best way to reinforce a shipping container?
Here are some important steps to remember when considering how to reinforce a shipping container home.
Why do you need to reinforce a shipping container?
Designed to be filled to the brim, shipping containers can hold a vast amount of weight and be stacked up to nine high. The average steel shipping container is durable, rugged and large.
Available in several sizes, the most commonly used containers measure 20-foot, 30-foot, and 40-foot in length. The top, bottom, and sides are crafted from sheets of corrugated steel that are welded to rails and end frames.
When modifying containers for housing, you need to cut out sections for doors, windows, and to connect multiple containers. Once you start cutting out sections, the structural strength of the container weakens, hence the need to reinforce them.
If you wish to stack containers on top of each other after adding doors and windows, then you’ll need to add additional supports as you’ve weakened the structural integrity.
Creating windows and doors in your shipping container home
Even if your design consists of a single 40-foot container with no additional internal walls, you’ll probably still want to add windows along each side. And while you might be able to get away with adding glazing to each end without needing to reinforce, it’s still worth doing.
As relatively thin corrugated steel panels are used for the sides and top of the containers without additional support, they are likely to bend.
After cutting out the square or rectangle required for a door or window, you will want to build a frame around them using either metal strips or flat steel bars. Start by welding a strip below and above the window or door. Next, weld a strip to each side of the hole between the upper and lower strips.
If you’re creating a hole for a window or door that spans the entire height of the container, then add steel support beams that reach from the floor to the upper rail. Use 4×4 steel beams when adding vertical reinforcements.
Safely combining two or more shipping containers for a larger home
The industry-standard shipping containers are 8 feet wide, 8 feet high and either 20 or 40 feet long. Using a single container gives you between 160 and 320 square feet of living space. Hence why most shipping container homes are made up of multiple containers.
Combining multiple containers into a single living space is more complex than creating an opening for a door or window. The process also depends on whether you are placing two containers side by side or stacking them.
If you’re placing two containers side by side, you need to remove the corrugated steel panels on the sides that face each other. Removing these panels limits the structural integrity of the rails that run the length of the container.
Solving this issue involves adding steel beams to support the upper rails where the two units meet to improve the overall structural integrity of the combined units.
Before attempting to combine containers, you’ll need to ensure the foundations and that the two containers are perfectly level. If one container is slightly higher, it can be difficult to seal them together. So, always double-check to ensure that they align perfectly.
Another thing to be aware of when combining two containers is the gap between them. While this may be tiny to the naked eye, to the elements, it’s big enough to cause serious issues. So, you’ll want to try and minimise this gap.
To protect against the elements and leaks, you need to seal the gap. One way to seal two containers is by installing rolled roof flashing on the interior, followed by a layer of roofing cement and exterior flashing.
Stacking multiple shipping containers to create a 2-storey house
In their original form, stacking multiple shipping containers is a no-brainer as they are designed for it. When stacking containers, the weight from the upper container is largely transferred to the corner posts of the lower container.
However, if the lower container has cut-outs for windows or doors, the rails may need additional reinforcement with 4×4 steel beams to ensure the top container doesn’t cause the lower one to buckle under the weight.
You’ll need to add steel beams if you’re stacking offset containers. And of course, you’ll need to add supports to the part of the shipping container that overhangs to counterbalance the weight.
Similarly, if you’re stacking a shorter container on top of a longer one, a 20-foot on top of a 40-foot container, for example, then you’ll need to add steel beams to the lower unit. Typically, you’d add a steel beam on the roof of the lower container along where the shorter container ends.
How to reinforce shipping containers for use underground
When thinking about how to reinforce a shipping container home for underground, you need to take a slightly different approach. Rather than adding support around a window or door frame, you’ll need to add extra steel beam supports to the entire container.
Shipping containers can hold an enormous amount of weight and easily be stacked, even when full. However, they are not designed to withstand significant pressure on the top and sides.
By lowering a container in the ground and covering it with soil, you place a significant amount of pressure on it. As a result, the thin corrugated steel walls may buckle or at worse, collapse.
To reinforce underground containers, you should weld steel posts vertically across both lengths of the interior. Space the beams three feet apart. Finally, weld steel posts along the inner top of the container, aligning the upper posts with the side posts.
Welding tips for adding beams to a shipping container
There are two options when using beams to strengthening a shipping container. You could use wood frames and beams. However, steel is preferable as it offers more stability and can be welded directly to the existing structure.
That said, if you’re new to welding, it’s best to start small and build confidence. Don’t jump to working on your containers as you might damage your new home or yourself.
Thankfully, basic welding is simple but does require having the right safety precautions in place. As welding involves the use of strong electrical currents and extremely high temperatures, you also need to wear protective gear.
Before welding, start by clean the surfaces you intend to weld with a wire brush to remove any dirt or rust. You may also want to pre-mount the reinforcements by drilling holes to securing the steel beams with screws.
Otherwise, consider erecting temporary wood supports to hold the steel bars in place as you weld.
Start the welding process with tack welding, which involves adding a few welds at each end to secure the reinforcements. After adding a few welds to tack the beams in place, begin welding the seams.
Can you remove too much steel?
In a word, yes, you can remove too much steel and create another set of problems. Sadly, some people over-modify their containers. They go gun-ho and start cutting holes all over the containers without considering the impact on the structural integrity.
Adding too many holes to a container will incur additional costs as it will require even more steel beams to reinforce it. Not to mention the time and cost of having to weld the steel beams in place.
When designing your ideal shipping container home, you should work with an architect or designer who can advise you on the best placements for windows and doors while keeping the amount of reinforcement you need to add down to a minimum.
Should I hire a conversion company?
While it’s possible to learn how to reinforce a shipping container house and then give it a go, it might be best to work with a shipping container conversion company. The same is true for adding insulation to your container home.
For example, a professional welder will know the right amount to cut out a section without removing too much. It can be costly to replace the excess steel that has been cut away by mistake. Also, removing too much is dangerous as it damages the structural integrity of the shipping container.
A conversion company will also understand the risks and know exactly how to modify each container while ensuring it retains its integrity and durability. They’ll also be able to install all of the necessary utilities, allowing you to move in without hassle.
That’s How to reinforce a shipping container home to ensure durability
As you now have a better idea of how to reinforce a shipping container home and why you should use a professional, you can start to build a more durable home.
Even if you decide to DIY your build, it’s worth getting the proper advice to ensure you don’t destroy the structural integrity of your shipping containers when creating holes for doors and windows.