
What to check on a container before you buy it for a build
I've spent a lot of time around containers, mostly delivery/site stuff, and one thing I see people mess up early is buying the wrong box. For basic storage, you can get away with a rougher unit. For a build? Different story. You're cutting openings, insulating, maybe living in it. You want it square, dry, and not full of some mystery smell you can't get rid of later.
First thing: ask for the actual container number. Four letters, six digits, then one check digit in a little box. There are free check digit calculators online. If the number doesn't match, something is off. Sometimes it just means the seller is using photos from another container.
A real yard with the box sitting there can give you the number in ten seconds. If they get vague, that tells you something.
Check the size/type code too. A 40 high cube dry box is usually marked something like 45G1. A standard 20 is usually 22G1. For a build, I'd almost always want high cube. That extra foot of height sounds small until you lose inches to insulation, ceiling, subfloor, flooring, all that. Standard height can feel tight fast.
Look at the CSC plate on the door. It'll show build date and weight info. Sellers can call something "newer" all day, but the plate doesn't care.
Then do the simple stuff.
Get inside, shut the doors, lights off. If you see daylight, that's a hole. Tiny pinholes in the roof matter more than people think.
Open and close both doors. Fully. If they bind badly, the box might be racked. For a build, that's one I'd be nervous about. You don't want to start with a twisted frame and then cut big openings into it.
Check the floor. Container floors are usually treated plywood, and some used boxes have weird stains or cargo smells that never really leave. If you're building over it, you still want to know what you're sealing in.
Door gaskets matter too. Flexible is good. Cracked and flat is not. Surface rust is normal. Flaking rust around bottom rails or corner posts is a different story.
If you can't see it in person, ask for a video of the actual unit. Container number visible at the start, walkaround, inside with doors closed and lights off. Not stock photos. Not "one like this." If they won't do it, I'd move on.
Anyone here bought a container unseen for a build and had it work out? Curious if it's ever actually fine, or just a gamble that sometimes goes okay.