No, not if it is done right. Cutting into a wind and water tight container does open the seal at that spot, but our shop welds a steel frame around every cut and finishes the edge to shed water before anything gets mounted in it. A door, window or vent bolted straight to unframed corrugation is what actually leaks, not the cut itself.
A container arrives from the yard as a closed steel box, and every panel on it is doing structural work, not just sitting there as a wall. Those corrugations are structural. They carry the racking load when the box gets picked up off a tilt-bed, stacked on another unit, or landed on ground that sits a little uneven, and the same skin doing that work is also your water barrier. The moment our shop puts a saw to that panel for a roll-up door, a personnel door, a window, a skylight or a vent, two things happen at once: the box loses some of the stiffness that panel was providing, and there is now a raw, unfinished edge of cut steel where a continuous sealed skin used to be.
Neither of those is a problem by itself. Both of them are the reason a modification is a fabrication job and not a five minute cutout.
This is the part that decides whether the finished container is still weather-tight. We weld a steel frame, header and jambs on a door or window, a curb on a roof skylight, around every opening before the door, glass or vent assembly ever goes in. That frame does two jobs at once: it carries the structural load that used to run through the panel, and it gives water a clean, finished edge to run off instead of a raw cut edge to sit against and eventually rust and channel water inward. A threshold on a personnel door gets built to shed water away from the opening, not toward it, for the exact same reason.
Skip the welded frame and mount a door or window straight to bare corrugation, and the trouble does not show up right away. The assembly seems fine for a while, then the first real cold snap works it loose: the panel around the opening was never given anything to carry its load, so the whole thing shifts out of square, sticks, and stops sealing. That outcome comes from a shortcut in the framing step, not from the fact that steel got cut in the first place. Frame it correctly and the same cut never gets there.
It is also worth separating a real leak from condensation, sometimes called container rain. A closed container can bead water on the ceiling from moisture already trapped inside, with no leak anywhere, which is a ventilation issue and not a sign that a modification failed.
A welded frame is permanent. The seal around a door or window is not, and it is not meant to be. Weather stripping and door sweeps are wear parts, replaceable, and they do the day to day sealing on top of a properly framed opening. Expecting to swap a sweep every so often is normal maintenance. Watching a whole door assembly start leaking around the frame itself, months after installation, is a sign the frame was not built correctly in the first place, and that is what a real build guards against.
Tell us what you want cut and how you will use the space, and we will spec the framing along with it.
Same-day reply. We'll send a real number, a real delivery window, and any photos we need to confirm fit.
You'll hear back from us today (or first thing tomorrow if it's late). For anything urgent, call (276) 237-6144.