Shipping containers are everywhere, crossing oceans, stacked at ports, and transformed into homes, offices, and pop-up shops. Yet one question continues to surface among logistics professionals, builders, and curious buyers alike: what are shipping containers made of?
At first glance, they appear to be nothing more than large steel boxes. In reality, their composition, texture, dimensions, and manufacturing origins are the result of decades of engineering refinement. Understanding what shipping containers are made of helps explain why they can survive saltwater voyages, extreme weather conditions, and heavy stacking loads for decades.
In this article, we explore the materials used in shipping containers, how their size and height affect construction, where they are manufactured, and what makes their steel surface so distinctive.
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What Material is Used for Shipping Containers?
When asking what shipping containers are made of, the short answer is steel, but not just any steel.
Primary Material: Weathering Steel (Corten Steel)
Most modern shipping containers are constructed using weathering steel, commonly referred to as Corten steel.
What is a corrugated sheet?
This alloy is specifically designed to resist corrosion by forming a protective outer layer of oxidation when exposed to moisture and air.
Unlike ordinary steel, which continues to rust and weaken, weathering steel stabilizes over time. The rust-like patina becomes a shield, preventing deeper corrosion and structural decay.
Key properties of container grade steel include:
- High tensile strength
- Resistance to saltwater exposure
- Ability to withstand temperature fluctuations
- Long service life with minimal maintenance
This material choice answers the core question of what shipping containers are made of in a practical sense. They are engineered to survive the harshest global transport environments.
Is Corrugated Steel Rust proof?
The shipping container steel texture is one of its most recognizable features.
The textured surface results from corrugated steel rolling processes, protective primer coatings, and industrial paint layers designed for UV and salt resistance.
Texture is not polished smooth because rougher surfaces hold protective coatings better, minor scratches do not compromise structural integrity, and maintenance and repainting are easier.
For architects and designers, has become an aesthetic feature, often left exposed in container-based structures.
Shiping Container Structural Components and Their Materials
Beyond the walls, a container consists of several key structural elements.
Shipping Container Corner Castings
- Made from high grade forged steel
- Allow cranes to lift containers safely
- Enable standardized stacking and locking
Shipping Container Roof Panels
- Thin but strong steel sheets
- Designed to handle environmental exposure rather than heavy loads
Shipping Container Doors
- Steel frames with locking bars
- Rubber gaskets for watertight sealing
Each component supports the container’s integrity while maintaining international transport standards.
Shipping Container Flooring
While steel dominates the exterior, the flooring tells a different story.
Inside most containers, the flooring is made from heavy-duty marine plywood or bamboo laminates, reinforced by steel cross supports.
These floors are treated to resist:
- Moisture
- Fungal growth
- Heavy point loads from cargo
Newer environmental regulations are transforming treatment practices; flooring remains a critical component in explaining shipping container construction beyond the metal shell.
Shipping Container Protective Coatings and Paint Layers
Beyond steel, containers are coated with zinc-rich primers, epoxy intermediate layers, and marine-grade topcoats.
These layers protect the steel underneath and extend container life well beyond 15 years in active service.
How Tall Are Shipping Containers?
One of the most frequently asked dimensional questions is how tall are shipping containers.
Shipping Container Standard Heights
Standard container: 8 feet 6 inches (2.59 m)
High cube container: 9 feet 6 inches (2.89 m)
High cube containers are especially popular for:
- Lightweight but voluminous cargo
- Container homes and offices
- Modular construction projects
Height directly influences wall reinforcement, steel thickness, and overall material stress, making it an essential factor when discussing container composition.
What is the Size of a Typical Shipping Container?
Understanding the typical size of shipping container helps clarify why material choices are so critical.
Common ISO Container Sizes
20 foot Shipping Container:
Length: 20 ft
Width: 8 ft
Height: 8 ft 6 in
40 foot Shipping Container:
Length: 40 ft
Width: 8 ft
Height: 8 ft 6 in or 9 ft 6 in (high cube)
The longer the container, the greater the structural stress on the steel frame. This is why larger containers often feature reinforced cross members and thicker corner posts.
How Size Influences Material Thickness
Smaller containers can rely on slightly lighter steel panels, while longer units require enhanced rigidity to prevent twisting during lifting and transport.
Engineers must balance:
- Weight limits
- Payload capacity
- Structural longevity
Balance is a core reason shipping containers have remained standardized for decades.
Where Are Shipping Containers Manufactured?
Another important question is where are shipping containers manufactured.
Global Manufacturing Hubs
Over 85 percent of new shipping containers are produced in China, with major manufacturing clusters located in:
- Guangdong Province
- Jiangsu Province
- Shanghai industrial zones
Other countries with container production include:
- South Korea
- Vietnam
- India
China dominates production due to access to raw steel, established port infrastructure, and cost-efficient manufacturing processes.
Despite global production, all containers must meet ISO 668 standards, ensuring material consistency regardless of origin.
Quality Control in Container Manufacturing
Factories follow strict protocols, including ultrasonic testing of steel, load-bearing simulations, and weather resistance checks.
Processes ensure that containers remain structurally sound throughout their lifespan, no matter where they are manufactured.
Environmental Considerations and Material Evolution
Modern container manufacturing is shifting toward sustainability. Bamboo flooring, low VOC paints, and reduced chemical treatments are becoming more common.
Reused containers also play a major role in reducing steel demand, lowering construction waste, and promoting modular architecture.
Shipping container material’s durability makes repurposing a viable alternative to scrapping.
Why Material Choice Defines Shipping Container Longevity
Shipping containers are not disposable structures. Their steel composition, engineered structure, and standardized dimensions enable them to cross oceans repeatedly, stack safely under extreme loads, and adapt to new uses beyond shipping.
A clear understanding of their materials and construction helps buyers, builders, and logistics professionals make informed decisions for transport and design applications.
Conclusion
Shipping containers stand as one of the most effective examples of modern industrial design. Their materials are selected not only for appearance but also for strength, longevity, and adaptability. From weathering steel exteriors to engineered flooring and globally standardized manufacturing, every element plays a role in making containers reliable across countless applications.
On-Site Storage Solutions
If you are considering a storage solution, understanding what shipping containers are made of makes choosing the right unit far more straightforward. On-Site Storage Solutions provides durable storage containers built to handle demanding environments, heavy use, and long-term storage needs.
If your project requires on-site storage for construction, commercial operations, or temporary space, our team is ready to help you find the right fit. Call (888) 977 9085 to speak with an expert and get dependable storage delivered to your location.
FREQUENTLY ASKED QUESTIONS
Shipping container walls are usually constructed with 14-gauge steel, measuring around 0.075 inches thick. The frame, pillars, and rails of the container, on the other hand, are made of 7-gauge tubular steel, which is thicker at 0.187 inches.
Cargo containers are primarily made corten steel. The walls, roof, and floor of these containers are constructed using corrugated steel panels that provide strength and durability. The steel used is typically weather-resistant and able to withstand harsh conditions during transportation. The interior may also feature plywood or other materials for insulation and protection of the cargo.
The thickness of a shipping container wall is typically 0.075 inches. The walls are made of corrugated steel sheets that provide structural strength and durability to withstand the stresses of transportation and stacking.
The floor of a shipping container is commonly a 1-1/8 inch thick marine plywood. This particular type of plywood is specially designed to withstand the harsh conditions of marine environments, ensuring durability and strength. However, it is worth noting that certain containers may feature alternative flooring materials like bamboo, vinyl, or even steel.