Are shipping containers really watertight?
A container sold as wind and watertight, cargo worthy, or one-trip is sealed against rain: steel walls and roof, welded seams, and rubber door gaskets that close tight. What a container is not is condensation-proof or air-conditioned — moisture from the air inside will still bead on the cold steel on a clear night — so dry storage is about the grade you buy and the vents you add, not the box alone.
What the grades promise
Wind and watertight (WWT) is the baseline for a used container: no holes, doors that seal, a roof that keeps rain out. It will have rust, dents and faded paint, and that is the product, not a defect. It is the right grade for plain storage and the one most people should buy — see the 20ft WWT.
Cargo worthy (CW) is a used box that has passed a structural survey and could legally go back to sea. It is at least as tight as WWT and generally straighter. One-trip is near-new: one loaded voyage, factory paint, fresh gaskets. All three keep rain out; they differ in cosmetics, floor condition and how many years of paint you are starting with. Our one-trip vs used guide goes deeper.
Check any used box on day one: stand inside with the doors shut on a bright day and look for pinholes of daylight in the roof and walls. Any you find is a leak, and around here it will show itself in the first afternoon downpour. Report it immediately, while the delivery is fresh.
Condensation and security
Watertight from outside does not mean dry inside. In Pine Belt humidity a sealed steel box cools below the dew point at night and water forms on the ceiling and drips on whatever is under it. Louvered vents, a solar fan if you are serious, desiccant, and never loading damp goods are the fixes; the full method is in how to stop condensation. Vents are on the accessories page.
Security is the other half. Container doors lock with the swing bars and a padlock, and a plain padlock is the weak point — bolt cutters take it in seconds. A welded or bolt-on lock box that shrouds a puck-style padlock is the fix that actually works; it is the cheapest security upgrade on the site and the first thing to add. More in securing a container on a jobsite. See containers for sale — delivered price by ZIP
Buying a container?
Longleaf sells used and one-trip 20ft and 40ft shipping containers, delivered by tilt-bed across the Pine Belt. Enter your ZIP for the delivered price — it comes straight from the supplier feed and already includes the haul. Locks, vents, shelving and lights are on the accessories page. We sell; we do not rent.
- 20ft Standard Cargo Worthy (used) — from $2,885 delivered
- 20ft Standard One Trip (new) — from $3,635 delivered
- 20ft Standard Wind & Watertight (used) — from $2,470 delivered
- 40ft High Cube Cargo Worthy (used) — from $3,525 delivered
- 40ft High Cube One Trip (new) — from $4,925 delivered
- 40ft High Cube Wind & Watertight (used) — from $3,210 delivered
- 40ft Standard Cargo Worthy (used) — from $3,525 delivered
- 40ft Standard One Trip (new) — from $6,355 delivered
- 40ft Standard Wind & Watertight (used) — from $3,160 delivered
Keep reading
- How much does a shipping container weigh? — Shipping container weight: empty tare for a 20ft and 40ft, the maximum gross rating, why a loaded box never nears it, and what the weight means for your pad.
- Will a shipping container damage my driveway? — Will a shipping container damage a driveway: why the truck, the slide-off and four loaded corners are the risk, and how to protect concrete or asphalt.
- How to get ready for delivery day — Prepare for a shipping container delivery: mark the spot, clear the straight run, firm up the ground, set corner blocks, and have someone there on the day.
- How do you secure a container on a jobsite? — Securing a shipping container on a jobsite: why a lock box and puck lock beat any padlock, where to point the doors, and when a container is the wrong answer.
- Can you put a shipping container on grass? — Shipping container on grass or dirt: why the truck is the first problem, why a box you own should never sit flat on turf, and the cheap pad that fixes it.
Across the Pine Belt
Hattiesburg · Petal · Laurel · Ellisville · Purvis · Sumrall · Columbia · Collins · Seminary · Wiggins