If you’re modifying a shipping container with doors, windows, vents, or cutouts, you can’t forget one critical step: flashing.
Flashing is what keeps water, wind, pests, and debris out of your container once you've made a cut. Whether it's around a man door, sidewall window, or service hatch, improper or missing flashing can lead to leaks, rust, insulation damage, and mold.
In this lesson, we’ll break down why flashing is essential, how to install it properly, and how CMW’s flashing kits take the guesswork out of the process, whether you're a seasoned pro or first-time DIYer.
What Is Flashing?
Flashing is a thin material, usually aluminum or steel, installed around openings to direct water away from vulnerable seams and joints. It acts as a bridge between the steel container and your installed component (like a door or window), sealing gaps and improving weatherproofing.
Why You Need Flashing on Containers
Shipping containers weren’t designed to be homes, shops, or offices, so once you start modifying them, you risk water making its way in.
Without proper flashing:
- Rain can seep behind trims and corrode interior walls
- Snowmelt and condensation can soak insulation
- Bugs and rodents find open gaps to enter
- Air gaps reduce HVAC efficiency and cause heat loss
- Plywood liners and flooring can rot from trapped moisture
Especially in cold or wet climates, flashing is non-negotiable.
Where to Use Flashing
- Around man doors
- Around windows (sidewall, end wall, kiosk, or slider)
- Over vents, fans, and louvers
- Between joined containers (like double-wides or towers)
- On roof penetrations (vents, solar panels, chimneys)
Types of Flashing We Use at CMW
Door Flashing
CMW's Door Flashing Kit allows you to spray foam container doors while keeping them useable and add a finished edge.
Wall Flashing
CMW's Wall Flashing Kit creates a clean finished look and retains spray foam.
Why Use CMW’s Flashing Kits?
At Container Modification World, we’ve developed no-weld flashing kits that:
- Are precision-cut to fit our pre-framed doors and windows
- Work on standard corrugated steel walls
- Include self-tapping screws for fast, easy install
- Are made in-house with durable materials that stand up to harsh Canadian climates
- Look clean, professional, and symmetrical
Whether you’re a contractor or DIY builder, our kits save time and eliminate mistakes.
