Step by Step 20’ Shipping Container Modification - Favorite Insulated Modular Interior Wall System

Chuck Prongua
Step by Step 20’ Shipping Container Modification - Favorite Insulated Modular Interior Wall System

Step by Step 20’ Shipping Container Modification - Our Favorite Insulated Modular Interior Wall System

This Shipping Container Modification Step by Step video will explain our favorite way to frame, insulate and line a sea container.

Follow us along as we design this container into a modular interior structure using CSM brackets, strut channel and steel stud framing, spray foam insulation, and white PVC reline car wash panels.

We will also show you how to install access hatches on either end of the container, including how to weld a container door shut!

This unique container conversion is designed this way so the customer can pull cables longer than 20-feet through the sea can to work on it, couple it, and push it out the other end.



Purchase Container Modification World Products Featured in The Video


Framing, Insulating, and Lining a Shipping Container the Right Way

In this walkthrough, Channing McCorriston, The Container Guy, demonstrates a modern, modular approach to framing, insulating, and lining the interior of a shipping container.

Instead of relying on traditional wood 2x4 studs, this build uses a steel-based system designed for durability, flexibility, and long-term performance. The result is a clean, insulated, vapor-tight interior suitable for mechanical rooms, electrical systems, or climate-controlled spaces.

A Modular Strut Channel Framing System

At the core of the build is a strut channel framing system combined with CSM brackets and strut strapping.

This steel system offers several advantages over wood:

  • Lighter weight

  • Perfectly straight framing

  • Roughly one inch more interior space

  • Fully modular mounting options

The modular layout allows fixtures and panels to be mounted almost anywhere inside the container. Because the framing system integrates directly with the steel shell, it creates a highly adaptable interior structure.

Spray Foam Insulation for a Complete Vapor Barrier

Two inches of spray foam are applied throughout the container, including around corner castings and roof edges.

This serves multiple purposes:

  • Creates a continuous vapor barrier

  • Prevents condensation

  • Adds rigidity to the structure

  • Locks the steel framing in place

Properly insulating around corner castings is especially important, as exposed steel in these areas can cause condensation and thermal bridging.

Steel Stud Framing Details

The build uses 2.5-inch light-gauge steel studs with pre-punched openings for electrical wiring and stiffener bars.

These studs are installed into top and bottom tracks and secured with screws or a crimping tool. They are non-structural, meaning they are designed to hold wall coverings rather than support loads.

Consistent measurement is critical so that wiring loops and stiffener bars align properly throughout the installation.

Steel studs outperform wood in container builds due to their dimensional consistency and resistance to warping.

Fire-Rated Access Hatches

Two insulated, fire-rated access hatches are installed — one in the container door and one on the back wall.

These hatches make it possible to pull long cabling through the container without removing panels or compromising insulation.

Each hatch includes:

  • A modular frame

  • Silicone sealing

  • Riveted installation for durability

This design allows clean cable routing in heated container applications where cables exceed 20 feet in length.

Interior Wall Panels: PVC Reline Instead of Plywood

Rather than using plywood for interior lining, this build features white PVC reline panels.

These panels are:

  • Fire-rated

  • Durable

  • Easy to clean

  • Pressure washable

  • Built with a hollow honeycomb structure for strength

The panels install using a J-channel system attached to strut strapping. They interlock cleanly, creating a smooth, professional finish.

Compared to plywood, PVC panels offer superior moisture resistance and lower maintenance.

Door Modifications and Structural Considerations

Half-glass windows are installed into the container doors, requiring precise cutting to maintain structural integrity, especially when panic hardware is present.

In this case, the doors were welded shut for security and sealed with spray foam. However, a bolt-on kit approach is often preferred for cleaner future modifications.

Electrical and Plumbing Without Thermal Bridging

Instead of welding steel conduit into the container walls — which creates thermal bridges and condensation points — wiring is run through drilled openings in the thin steel walls.

The container walls are approximately 1.6 millimeters thick, making drilling straightforward. After running wiring, penetrations are sealed with duct seal or foam.

This method is more flexible and significantly reduces condensation risk.

A Prototype for Modern Container Interiors

This build represents a best-practice model for container interior envelopes.

By combining:

  • Modular steel strut framing

  • Light-gauge steel studs

  • Spray foam insulation

  • Fire-rated access hatches

  • PVC reline wall panels

the container becomes a durable, vapor-tight, and highly customizable interior environment.

Final Thoughts

Shipping container interiors require a different approach than traditional construction.

Steel stud framing and modular strut systems provide straighter walls, better space efficiency, and greater flexibility than wood. When combined with proper spray foam insulation and moisture-resistant wall panels, the result is a clean, professional interior built for long-term performance.

This approach sets a new standard for container modification, especially in engineering, electrical, and mechanical applications where durability and adaptability matter most.