Think Inside the Box Blog | Shipping Container News

What Are Shipping Containers Made of? (Materials, Parts & Specs)

Written by Becca Hubert | Aug 5, 2026

Shipping containers are built almost entirely from corten steel, a weathering steel alloy that resists rust without ever needing paint. The frame, corrugated wall panels, cargo doors, and cross members are all corten. Everything else on the container (flooring, locks, hardware) is a different material, chosen for a specific job.

Here's what's actually in each part, and why it's built that way.

Why Corten Steel?

Corten steel was developed to eliminate the need for painting. It's weldable, and when a piece of paint or coating does chip, a thin layer of rust forms at the surface and stops there. It doesn't creep deeper into the metal. That's the whole reason a container built in a factory can spend years outside, get knocked around a job site, and still hold its structural integrity.

Container Components at a Glance

Corner castings

Cast steel, welded to the corner posts. Built to take a crane hook or a stack of loaded containers above them.

Twist locks

Steel locking pins. Pivot into the corner casting to anchor the container to a truck bed, foundation, or another container.

Cross members

Steel joists under the floor. Create a gap between the ground and the flooring so moisture doesn't seep in from underneath, which is also why many container structures skip a traditional foundation.

Forklift pockets

Reinforced steel slots along the base. Let a forklift lift and move the unit. Not always rated for use once a container's been modified and gained weight.

Cargo doors

Corten steel, same as the walls. Built to keep cargo secure and weather out on a multi-week ocean voyage, which is overkill in the best possible way for a jobsite.

CSC plate

A steel data plate, not a material choice. Certifies a qualified inspector confirmed the container is structurally sound and safe to stack or lift.

Falcon plate

Falcon's own plate, confirming the modified structure meets our standards, not just the shipping industry's.

Flooring

Marine-grade plywood (standard) or bamboo (increasingly common). Different material, different tradeoffs, covered below.

What About the Floor?

The floor is the one place a container isn't steel. Most come with marine-grade plywood, treated with a small amount of insecticide so nothing hitches a ride during the container's working life. That insecticide doesn't off-gas or aerosolize. It's a problem for bugs, not for the people standing on it. We trust it enough that we kept the original plywood floor in our own container-based office.

Bamboo flooring has been showing up more often, mostly because it's gotten cheaper and easier to source. It's mildew-resistant, durable, and a renewable material, which makes it a common upgrade for containers converted into living spaces where the floor is also part of the finish. If you see a woven grain pattern underfoot instead of plywood, that's bamboo.

 
 

 

Why the Material Breakdown Matters

A corten steel frame is what lets a container skip a foundation, survive a Gulf Coast summer, and get stacked without engineering gymnastics. Knowing what's underneath the paint is the difference between spec'ing a structure that holds up and one that surprises you two years in.

Shipping containers are simple structures by design, which is exactly what makes them a solid base for offices, living space, and jobsite storage.

Explore Falcon's floor plans and resource library to see how a standard container gets adapted for real-world use, and when you're ready, our team can help you pick the right starting point.

Frequently Asked Questions About Container Materials

What type of steel are shipping containers made of?

Corten steel, also called weathering steel. It's the material used for the frame, corrugated wall panels, cargo doors, and cross members. 

Why don't shipping containers need to be painted?

Corten steel was engineered to skip painting. When a coating chips, the exposed steel forms a thin protective rust layer instead of corroding further. 

What is the floor of a shipping container made of?

Most container floors are marine-grade plywood treated with insecticide. Bamboo flooring is a growing alternative, especially in containers converted for living space. 

Is the insecticide in shipping container flooring safe?

Yes. It's applied to prevent insects during the container's working life and doesn't aerosolize, so it isn't a risk to people in the space. 

What's the difference between a CSC plate and a Falcon plate?

A CSC plate certifies a container meets international shipping safety standards. A Falcon plate is specific to Falcon-modified structures and confirms the unit also meets our own quality and safety standards.