Guide
Sea can grades and how to inspect a used container
Container grades are how dealers describe condition, and the gap between them is real money. Here is what one-trip, cargo-worthy, wind and watertight and as-is mean, which one you need, and a ten-minute inspection that catches most problems.
One-trip (new)
Built in Asia, filled with cargo for one voyage, then sold. Straight panels, clean floors, original paint and working seals. The right grade for offices, cabins, homes and anywhere looks matter. As of late 2026, about $2,800–$4,500 for a 20 ft and $4,250–$7,000 for a 40 ft high cube.
Cargo-worthy (CW)
A used container still sound enough to carry cargo by sea or rail. It should have a CSC safety approval plate on the door, and some sellers provide a survey certificate. Expect dents, scrapes and surface rust, but no holes and a solid structure. Buy cargo-worthy if you will ship in it; for storage it is usually more than you need. Typically $300–$600 more than wind and watertight.
Wind and watertight (WWT)
Retired from shipping but still sealed against rain, snow and wind: no holes, doors that close and seal, a sound floor. Not certified for shipping. This is the standard grade for storage and the best value for most buyers.
As-is
Sold with known problems: holes, rot in the floor, doors that bind, heavy rust. Fine for a parts box, a windbreak, or a project where you will cut it up anyway. Not something to rely on for keeping things dry. Ask exactly what is wrong and see it in person.
How to inspect a used container
- Light test: step inside, have someone close the doors, and let your eyes adjust. Any daylight is a hole.
- Roof: look along it from a ladder or drone photos. Dents that hold water become rust holes.
- Floor: walk the whole floor, especially near the doors. Soft or delaminating plywood needs replacing. Container floors are usually treated with pesticide at the factory, which matters if you will live or work in it.
- Rust: surface rust is cosmetic; flaking, bubbling or holes in the corner posts, bottom rails or cross-members underneath are structural.
- Doors: the locking bars should turn by hand, and the rubber gaskets should be whole, not cracked or torn.
- Square: the doors should close without lifting. If they bind, the frame may be twisted.
- Smell: a strong chemical smell can mean past cargo or a treated floor. Air it out before storing food or living in it.
Questions
What is the difference between cargo-worthy and wind and watertight?
Cargo-worthy containers are structurally good enough to be shipped again, usually with a valid CSC plate. Wind and watertight containers keep the weather out but are not certified for shipping. For storage on land, wind and watertight is enough.
What is a CSC plate?
A metal plate on the container door showing it was approved under the International Convention for Safe Containers, with its maximum gross weight, stacking strength and manufacture date. It matters if the container will be shipped, not for storage.
Which sea can grade should I buy?
Wind and watertight for storage, cargo-worthy if you will ship goods in it, and one-trip if you are converting it into an office, cabin or home or it will be on display.