Wind and Waterthight – what does it mean?
Welcome to a detailed glossary dedicated to one of the most important and also most frequently misunderstood terms in the field of shipping containers (transport containers). Wind and Watertight (WWT) If you are considering buying a used container, it is absolutely essential to know what this classification means in practice, what the limits of this class are, and how to distinguish it from other types of containers on the market.
What is a Wind and Watertight (WWT) container? – Definition and significance
Wind and Watertight (abbreviated WWT) literally means “resistant to wind and water”. It is a basic classification of the technical condition of a used shipping container, which:
- is structurally sound,
- does not let wind or water in (when used correctly),
- has no holes, cracks or damage to the walls, roof or floor that would allow water or wind to penetrate,
- provides reliable protection for stored items.
WWT is the most common condition in which containers are sold to the public after the end of their sea service. Usually these are containers that have been in operation for 10–20 years in international transport, but are still functional and safe for land storage.
Important note:
- WWT is not an official certification – it is not a legally binding standard, but a descriptive term whose exact definition may vary between suppliers.
- WWT is not the same as Cargo Worthy (CW) – WWT containers usually no longer have a valid CSC plate for maritime transport and are not intended for repeated use in intermodal transport.
Key features of a WWT container: What to expect
When buying a used container marked WWT, the following essential technical requirements should be met:
| Property | Specification and details |
|---|---|
| Structural integrity | The container retains its shape, has no deformations that threaten stability, and is free of holes and cracks. |
| Protection against water and wind | Water and wind ingress are excluded; a daylight test is negative (it is dark inside). |
| Door sealing | Rubber seals are intact, doors close tightly. |
| Door functionality | Doors move freely, locks work, hinges and latches are not rusted. |
| Floor | Usually plywood – solid, without rot, holes or signs of pest damage. |
| Roof and walls | No openings, no extensive corrosion; small cosmetic defects (dents, scratches) are common. |
| Ventilation | May contain ventilation openings that provide air exchange and reduce condensation. |
Note: Surface rust, partial patches or aesthetic damage do not prevent WWT status as long as key properties are not compromised.
Common mistakes and myths about WWT containers
The WWT label does not guarantee, for example:
- New or near‑new condition: WWT containers are used, typically 10–20 years old.
- Flawless appearance: Surface rust, dents, scratches and patches are common and usually only cosmetic.
- Insulation: Standard WWT containers are not insulated; interior temperature follows external conditions.
- Condensation protection: Without modifications, condensation can form on walls and roof.
- Pest resistance: Rubber seals can be damaged by rodents.
- Transport certification: WWT containers no longer have a valid CSC certificate for international shipping.
- Accessories: Lockboxes, shelving, ventilation or paint are not part of a standard WWT container.
Differences between WWT and other container classes
| Container class | Description & suitable use |
|---|---|
| Wind and Watertight (WWT) | Used, fully functional for land storage. No valid CSC plate. May have cosmetic defects. |
| Cargo Worthy (CW) | Higher class; meets stricter structural standards (stacking, crane lifting) and has a valid CSC certificate. |
| One‑Trip / New | Practically new container, only one trip from the factory. Minimal wear, suitable for representative projects. |
| As‑Is / As‑found | Lowest class, no guarantee. Often damaged, with holes or non‑functional doors. Suitable only for parts or specific purposes. |
Note: Every Cargo Worthy container is also WWT, but not vice‑versa.
How to properly inspect a WWT container before purchase
Professional inspection is the key to a successful purchase. Here is a detailed checklist:
- Undercarriage: Inspect bottom beams and corners for cracks, corrosion, missing parts.
- Doors: Open/close both doors. Check seals, hinges, latches (must not be rusted).
- Side walls: Look for deep corrosion, repair marks, dents.
- Front wall: No openings; check condition of ventilation holes.
- Roof: Outside – dents where water could collect; inside – signs of leakage or light spots.
- Interior floor: Walk the entire surface; it must not be soft, warped, damp, or holed.
- Daylight test: Close the container, shut all doors. If light penetrates, the container is not 100 % WWT.
Professional tip: Perform a “flashlight test” – have an assistant shine a flashlight around seams. No light should enter.
Typical uses of a WWT container
Thanks to their robust construction and relatively low price, WWT containers have a wide range of applications:
- Secure storage: Tools, materials, inventory, archives, personal belongings.
- Construction: Storage units, mobile workshops, staff facilities.
- Agriculture: Storage of feed, seed, fertilizer, equipment.
- Base for modifications: Garden shed, workshop, office, studio, base for a living container (new/one‑trip is preferable).
- Retail & events: Temporary stalls, shops, cafés, information centers.
- Emergency use: Humanitarian aid storage, temporary housing, command posts.
Risks and warning signs when buying a WWT container
Beware of low‑quality or even fraudulent offers. Watch out for:
- Too low a price – may be an “as‑is” container or have serious defects.
- No photos of the specific unit – always request current photos of the actual container.
- Refusal of a personal inspection – a reputable seller will allow inspection.
- Vague descriptions – only generic phrases like “normal wear” are suspicious.
- Pressure to buy quickly – do not let yourself be rushed into a decision.
- Unclear shipping terms – ask about conditions and cost of delivery to the destination.
Possible modifications and upgrades for WWT containers
A WWT container can be adapted to the intended use. Common modifications include:
| Modification | Description and benefit |
|---|---|
| Lockbox | Steel lockbox for a hanging lock, protects against break‑ins and greatly improves security. |
| New paint | Improves appearance, protects against corrosion, extends service life. |
| Ventilation | Installing vent grilles reduces condensation risk and keeps the interior drier. |
| Insulation | Sprayed PUR foam or panels – stabilises temperature, reduces condensation, enables year‑round use. |
| Windows and doors | Personnel doors and windows turn the container into a habitable, work or commercial space. |
| Shelving systems | Organises and efficiently uses interior space. |
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