Shipping container homes have become a popular alternative for those seeking affordable, eco-friendly housing that can be built almost anywhere. However, modifying a shipping container to build a home requires reinforcement. Here are some important steps to remember on how to reinforce a shipping container home.
Why Do You Need to Reinforce a Shipping Container?
Shipping containers can hold tens of thousands of pounds and be stacked nine high. The structural strength of the container weakens when you start cutting out sections.
Containers come in varying lengths, with 20-foot, 30-foot, and 40-foot containers being the most popular. The top, bottom, and sides are made using sheets of corrugated steel that are welded to rails and end frames.
When modifying containers for housing, you need to cut sections of metal for doors, windows, and connecting multiple containers. Cutting steel from the sides or ends limits the strength of the container. The rails support the load of additional containers when stacked but lose strength without the corrugated steel panels on the sides.
Framing Doors and Windows in Shipping Home Containers
No matter the size of the cut-out, you need to reinforce the rest of the wall. The corrugated steel panels used for the sides and top of the containers are relatively thin and likely to bend without support.
Frame windows and doors using metal strips or flat steel bars. Weld a strip below and above the window or door. Fit a strip on each side of the cut-out between the upper and lower strips.
If the window or door spans the entire height of the container, add steel support beams that reach from the floor to the upper rail. Use 4×4 steel beams when adding vertical reinforcements.
Merging Two or More Shipping Containers for a Larger Home
The standard ISO shipping containers are 8 feet wide and 20 to 40 feet long. A single container may only offer 160 to 320 square feet of living space, which is why most shipping container homes are made from multiple containers.
Merging containers involves more steps compared to reinforcing the opening for a door or window. The process also depends on whether you are placing two containers side by side or stacking them.
When placing containers side by side, you typically need to remove the corrugated steel panels on the sides that face each other. This limits the structural integrity of the rails that run the length of the container. Steel beams may be needed to support the upper rails where the two units meet.
The foundation must also be perfectly level before attempting to merge containers. If one container is slightly higher, you may struggle to seal them together. Always double-check to ensure that they align perfectly.
The corner posts on shipping containers also create a gap when merging two adjacent containers. To protect against leaks, you need to seal the gap. Sealing two containers often involves installing rolled roof flashing on the interior, followed by a layer of roofing cement and exterior flashing.
Stacking Multiple Shipping Containers for a Multi-Story Home
When containers are stacked directly on top of each other, the weight from the upper container is mostly transferred to the corner posts of the lower container. Shipping containers are designed for stacking. However, if the lower container has cut-outs for windows or doors, the rails may need additional reinforcement with 4×4 steel beams.
Steel beams are also needed when the stacked containers are offset from each other. For example, if the upper container partially rests on the lower container, steel beams should be welded directly below the corner posts of the upper container. This same process is used when stacking a shorter container on top of a longer one, such as a 20-foot container on top of a 40-foot container.
Reinforcing Underground Shipping Containers
If the container sits below ground, you should follow slightly different steps for reinforcing the container. Instead of adding support around a window or door frame, you need to support the entire container.
Shipping containers are designed to hold tremendous weight but are not designed to withstand significant pressure on the top and sides. The pressure from the soil may cause the thin corrugated steel walls to collapse.
To reinforce underground containers, weld steel posts vertically across both lengths of the interior. Space the beams two to three feet apart. Weld steel posts along the inner top of the container, aligning the upper posts with the side posts.
Tips for Welding Reinforcement Beams in a Container
While some contractors use wood frames to reinforce shipping container homes, steel offers more stability and can be welded directly to the existing structure. If you have never welded metal before, you should practice with a smaller project before potentially damaging your new home or yourself.
Basic welding is not overly complex but requires safety precautions. It involves the use of strong electrical currents and extremely high temperatures. You also need to wear protective gear.
Before welding, always clean the surfaces that 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 for securing the beams or steel bars with screws. Without screws, you may need to erect temporary wood supports to hold the steel supports 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.
Last Thoughts on Reinforcing Shipping Container Homes
When you cut squares and rectangles from a metal box, you need to reinforce it with more metal. The amount of reinforcement depends on the amount that you cut, where you cut it from, and where you plan on placing the box.
Cutting a window or door requires a metal frame consisting of four steel bars welded to the wall. If you plan on merging containers, you need to ensure that they are sealed to prevent leaks. If the container is placed underground, it needs reinforcement on all sides.
Along with these steps, consider consulting with a professional engineer or contractor who specializes in building shipping container homes. Proper engineering and construction help ensure that your new home remains structurally secure and habitable.