What to check on a used container before you accept it

1. Shut the doors and look for daylight

Get inside, pull both doors closed and let your eyes adjust for thirty seconds. Then look at the roof line, the four top corners, the seams down each side and the whole perimeter of the door frame.

Any daylight is water. This one test finds more problems than everything else on this list combined, and it takes half a minute.

2. The floor

Twenty-eight millimetres of marine-grade plywood on steel cross-members. It is the part that wears and the part that is expensive to fix.

Walk the whole length, including the corners. You are feeling for softness and spring, and looking for delamination, deep gouges, oil staining and any patch of discolouration that suggests something wet has sat there. Push down hard with your heel in a few places. A floor that flexes underfoot is a floor that has taken water from below.

3. The door gasket and the locking bars

Run a hand around the rubber gasket on both doors. You are looking for perishing, sections that have gone hard, and anywhere it has pulled away from the frame.

Then work all four locking bars. They should turn without a fight and the cams should pull the door firmly against the gasket at the end of travel. If a bar needs to be forced or will not seat, the door end has usually been knocked at some point and the frame is slightly out of square.

Open and close both doors fully. They should swing freely and hold at any angle.

4. The corner castings and the rails

Look at the eight corner castings — the steel blocks at each corner. They carry the entire weight and they are what a crane picks up. Cracks or serious distortion are a walk-away.

Then run your eye along the bottom side rails. This is where water sits, and it is where rust that matters starts. Surface rust is normal and cosmetic on any used unit. Rust that has gone through, flaked into layers or opened a hole is not.

5. Repairs, and what a good one looks like

Nearly every used container has been repaired. That is not a problem — a properly welded and sealed patch is fine and will outlast the rest of the panel. What you want to see is a repair that is fully welded around its perimeter and painted over.

What you do not want is silicone, sealant, rivets or a patch tacked at the corners. That is a repair done to get through a sale, not to keep water out.

6. The lock box

A lock box is a steel shroud welded over the padlock position on the right-hand door so that bolt cutters cannot reach the shackle. Check it is there, check the padlock you intend to use actually fits inside it, and check the door still closes with a lock in place.

7. Smell it

Thirty seconds inside with the doors shut tells you what the container last carried. A strong chemical smell, a persistent damp smell, or the sweetish smell of something organic that has gone off will not come out easily and will transfer to whatever you store in it. If it is going to hold anything you care about, this matters more than a dent does.

If you cannot inspect it yourself

Most people buying a container never see it before it arrives, which is why photographs of the actual unit matter. Ask for them — the door end, the floor from inside, both sides, the roof if it can be reached safely, and a close shot of anything that has been repaired. We send photographs of your actual container on request, before delivery, and if a unit will not photograph well that is usually a sign we should be offering you a different one.