Shipping containers are primarily made from corten steel, a weathering steel designed for durability and corrosion resistance.
Structural elements like corner castings and cross members provide the strength needed for stacking and heavy loads.
Most container floors are made from marine-grade plywood, with bamboo becoming a more sustainable alternative.
Seals, coatings and marine-grade paints protect containers from moisture, salt and extreme weather conditions.
Understanding container materials helps you make better decisions for cutting, modifying and long-term performance.
Shipping containers might seem simple at first glance, but the closer you look, the more you’ll see how clever the design is. It’s so clever, in fact, that the entire global supply chain has been built around it.
Shipping containers are more than just steel boxes. Designed to spend 15+ years on the open ocean, often stacked ten high, every unit must meet strict manufacturing standards, resulting in a level of quality and consistency that has made containers a go-to piece of infrastructure for a wealth of non-shipping uses too, including secure storage, site offices and tiny homes.
Let’s break down shipping containers to see what they’re made of.
Why container materials matter
If you’re considering a conversion project, you need to know what shipping containers are made of, so you can decide how to capitalise on their strengths, cover any weaknesses, and decide whether you’ll DIY or get professional help.
The materials a container is made of will guide your conversion efforts. If you’re looking to cut out windows and doors, for example, you need to know how that will affect structural integrity, which will be defined by the material that you’re cutting into. You may also need specialist tools and skills to work with certain materials too.
Pro tip: Buying a single trip/as new container for your conversion means starting with pristine Corten steel that, with proper preparation and upkeep, can last decades, even in extreme environments.
Shipping containers are made from corten steel, aka weathering steel: a metal alloy designed to develop a protective layer of rust. The name ‘corten’ is a portmanteau of the material’s two main assets: corrosion resistance and tensile strength.
Far from a weakness, the layer of rust on the outside of the container protects the metal beneath. This also means that new scratches and dents won’t rust through corten steel – they simply heal over.
Corten is also used in the load-bearing structural components of the container:
Corner castings: The reinforced steel blocks at each corner of the container that bear the weight of any containers stacked on top.
Cross members: The steel ribs beneath the floor that bear the weight of the cargo held within the container.
The flooring: plywood or bamboo
Plywood is the most common flooring found within shipping containers, and for good reason: it is cheap, strong and durable.
Bamboo is another standard flooring option that is increasing in popularity. While slightly more expensive (at least for now), it is hard-wearing, has great sustainability credentials, and offers a smoother and more attractive surface.
If you’re undertaking a conversion, keep in mind that in order to meet international quarantine standards, both plywood and bamboo floors are treated with insecticides and fungicides, so you need to wear appropriate PPEl if you remove them or sand them back.
There are a wealth of other material options for different use cases – vinyl, steel, epoxy, rubber – which you can learn about in our complete guide to shipping container flooring.
Seals and coatings
While corten steel is weather-resistant, durable and self-healing, painting the exterior of your container can extend its already long life even further, by adding another protective layer that delays the development of rust.
Marine-grade paints combine zinc-rich primers with epoxy topcoats that are resistant to both UV and corrosive salt air. They’re the go-to shipping container coating even if you’re nowhere near the sea.
In order to make the units wind and watertight (WWT), as well as pest- and dust-proof, shipping containers feature door seals and gaskets made of Ethylene Propylene Diene Monomer (EPDM), a rubber that is exceptionally durable and maintains its integrity in extreme temperatures (-40C to +120C).
Find the perfect container for your situation
Ready to secure your own shipping container?
We’re here to help. At shipping-containers.com.au we’re a 100% independent platform that offers all the expert advice you need on materials, modifications and more. We assist you in identifying the ideal container for your situation, then we connect you with local, vetted suppliers and modification partners who can deliver.
Andreas Atrott is the founder of shipping-containers.com.au, operated by Containerbase Pty Ltd (Hemmant, Queensland, Australia). He combines long-standing industry expertise with a hands-on approach to container sales, modifications, and custom solutions. He also conducts applied field research on the thermal and humidity behaviour of shipping containers in subtropical climates, publishing open datasets and reports under the Container Performance Research Series. His research dataset is available at https://doi.org/10.5281/zenodo.21466036 (ORCID: 0009-0007-9305-8058). His goal is to make buying and using shipping containers straightforward, reliable, and tailored to customer needs.
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July 3, 2025
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