Complete Buying Guide: How to Choose a Used 20-Foot Dry Shipping Container

Why choose a used 20-foot Dry shipping container?

The used 20-foot Dry shipping container, often called "20' DC" (Dry Container), is a rectangular steel box designed for transporting and storing dry goods. Its popularity stems from a rare balance between compactness, robustness, and price. A new model generally costs two to three times more than a revised container, while its lifespan remains very long thanks to the quality of its construction. For many professionals and individuals, a recent or revised used container therefore represents the best compromise.

This 20-foot format (about 6 meters long) offers an internal volume of approximately 33 m³, which corresponds to the loading capacity of a small truck. It can be handled by standard lifting equipment and transported on a container truck without an exceptional convoy. It is the most universal format on the market, suitable for a construction site as well as a farm, a business, or a conversion project.

Technical specifications to know before buying

Dimensions and volume

A 20-foot Dry container complies with ISO 668 and ISO 1496-1 standards. Its standard external dimensions are approximately 6.058 m long, 2.438 m wide, and 2.591 m high. Inside, there is generally 5.898 m long, 2.352 m wide, and 2.393 m high, giving a usable volume of about 33 m³. These values may vary slightly depending on the manufacturer, but they are the reference. Always check the exact dimensions if you plan a custom interior conversion.

Weight and payload

The tare weight of a 20-foot Dry container is commonly between 2,200 and 2,400 kg. The maximum payload can reach approximately 28,000 kg, for a maximum gross weight (MGW) of 30,480 kg. These figures are important for road transport: ensure that the vehicle and driver are authorized to carry the total mass (container + goods). An empty container can be towed by a standard truck, but once loaded, it requires a suitable vehicle and compliance with safety rules.

Materials and structure

The structure is made of Corten steel, a low-alloy steel that resists atmospheric corrosion thanks to the formation of a protective surface layer. The side walls and doors are made of corrugated sheet, ensuring rigidity and impact resistance. The floor is made of 28 mm thick marine plywood, dense and treated against moisture. The double rear doors are equipped with container locks (locking bars) and rubber seals. These seals are essential to ensure air and water tightness; they must be checked regularly and replaced if necessary.

Standards and certification

A container intended for maritime transport must be certified CSC (Convention for Safe Containers) and bear a valid approval plate. This plate, affixed to the door or wall, indicates the manufacturing date, country of approval, identification number, maximum gross mass, tare mass, payload, and date of the next examination. For static use (storage, conversion), CSC certification is not mandatory, but it remains a guarantee of quality and compliance. ISO 668 and ISO 1496-1 standards define dimensions and resistance tests.

The different used conditions: what does "revised" mean?

On the used market, several levels of condition are distinguished:

• "As is" container: sold without a watertightness guarantee, often with traces of rust, dents, or worn seals. Attractive price but risk of unpleasant surprises.
• "Wind & Watertight" (WWT) container: guaranteed wind and watertight. This is the minimum standard for secure storage. Seals are checked, holes and cracks are sealed.
• "Cargo Worthy" (CW) container: compliant for maritime transport, with valid CSC certification. More expensive, but suitable for shipping.
• Revised and repainted container: may include anti-corrosion treatment, seal replacement, or even new paint. The aesthetic appearance is improved, but check that the repairs are of good quality.

A revised used container guaranteed Wind & Watertight is generally the best choice for static use. It offers reliable protection against the weather without the price of new. At Transport Hosni Conteneur, the containers offered are revised and inspected, with a Wind & Watertight guarantee.

How to inspect a used 20-foot container before buying?

1. Check watertightness

Watertightness is the number one criterion. Inspect the door seals: they must be flexible, without cracks or gaps. Run your hand over the welds and walls looking for holes or cracks. The roof is often neglected: climb on it (with caution) or examine it from a ladder to detect any perforating corrosion. Ask if the container is guaranteed "Wind & Watertight" and if possible, do a water test (water jet on the roof and doors) before buying.

2. Examine the structure

Look for traces of perforating rust, significant deformations, or unprofessional repairs. The corner castings must be intact and not cracked, as they bear the handling stresses. The corrugated walls must not have deep dents that could affect rigidity. A container that has suffered a violent impact may have a weakened structure, even if the exterior looks fine.

3. Check the floor

The marine plywood floor must be solid and free of rot. Walk over the entire surface: a sound floor should not have soft spots or delamination. Check especially the corners and under the doors, where moisture can stagnate. Oil or chemical stains may indicate intense prior use; thorough cleaning may be necessary. In case of localized rot, a patch repair is possible, but replacing the affected board is often more reliable.

4. Test the doors and locks

The doors must open and close without forcing. The locking bars must slide without excessive play and the handles must engage correctly. Adjustment may be necessary if the doors close poorly. Check that the seals are not crushed or torn. A door that closes poorly is a source of water and air infiltration.

5. Check the CSC plate and markings

The CSC plate must be present and valid if you plan maritime transport. It indicates the date of the next examination. For static use, an expired plate is not a blocker, but it may indicate that the container has not been inspected recently. The regulatory markings (identification number, gross mass, etc.) must be legible.

Uses of the used 20-foot Dry container

Secure storage

The 20-foot container is ideal for storing sensitive goods: tools, materials, archives, furniture, electronic equipment. Its Wind & Watertight seal protects it from rain and wind, but not from ambient humidity. For long-term storage, add a moisture absorber or suitable ventilation, as condensation can appear with temperature variations. A well-maintained container stays dry inside.

Transport of goods

Compliant with maritime standards, it can be shipped by rail, road, or sea. It is stackable up to nine units on a ship and can be handled by lifting equipment equipped with spreaders or hooks suitable for the corner castings. For road transport, it must be loaded on a suitable vehicle, respecting the weight and dimension limits of the highway code.

Modular conversion

The 20-foot Dry container can be transformed into a site office, technical room, workshop, changing room, or even modular housing after conversion work. Its internal volume allows for insulation, a partition, electrical systems, and ventilation. Conversion for habitable use generally requires thermal insulation and reinforced air tightness, as well as compliance with local building regulations. The marine plywood floor can be covered with a suitable floor covering.

Comparison with other container types

The choice of a container depends on the nature of the load, weight constraints, volume, protection, and budget. Here is a brief comparison:

• 20-foot Dry: 33 m³, the most versatile for dry storage and general cargo transport.
• 40-foot Dry: 67 m³, more economical per cubic meter transported, but requires a longer site and a suitable vehicle (semi-trailer).
• 40-foot High Cube: about 30 cm additional internal height (2.695 m), useful for bulky but light loads or a conversion with a false ceiling.
• 20-foot High Cube: internal height of about 2.684 m, less common on the used market.
• Open Top: open or removable roof, for loading tall objects from above.
• Flat Rack: without side walls or roof, for heavy or oversized loads, but without weather protection.
• Reefer: equipped with a refrigeration unit, for perishable goods or pharmaceuticals, heavier and more expensive.
• Tank: for liquids and gases, with a stainless steel tank.

The 20-foot Dry remains the most universal format for dry storage and general cargo transport. If you need more volume, a 40-foot may be more economical, but check the available space and handling means.

Regulations and transport in France

In France, a shipping container is considered an intermodal load unit. For road transport, it must be loaded on a suitable vehicle, respecting the weight and dimension limits of the highway code. The authorized gross train weight (GTW) and the vehicle's payload must be taken into account. An empty 20-foot container weighs about 2.3 tons; loaded, it can reach 30 tons. The driver must respect speed limits and signaling rules for wide or heavy loads.

For maritime transport, the container must be CSC certified and have a valid approval plate. This plate is issued after inspection and is valid for five years, renewable. In France, using a container as a site office may require a planning permission depending on the duration and location. If the installation duration is less than three months, a prior declaration is often not necessary, but beyond that, a development permit or planning permission may be required. For permanent use (housing, office), it is necessary to comply with the local urban plan (PLU) and construction rules (DTU). Check with your town hall before any installation.

Maintenance of a used container

A well-maintained used container retains its value and functionality for many years. Here are the essential operations:

• Regular visual inspection: walls, roof, floor, doors, seals, welds. Check that the roof does not have perforating corrosion or deformation.
• Door seals: clean and lubricate them with a silicone-based product to prevent them from drying out and cracking. Replace them if worn.
• Hinges and locks: grease periodically to ensure smooth operation.
• Metal structure: clean with clear water. In case of deep scratches or beginning rust, apply an anti-corrosion treatment and suitable paint. Brushing rusted areas followed by an anti-rust primer and a topcoat can stop corrosion. It is advisable to repaint every five to ten years, depending on exposure.
• Floor: clean with soapy water; avoid high-pressure jets that could lift wood fibers. For oil or chemical stains, use a suitable degreaser and rinse. A sound floor should not have soft spots or delamination.
• Condensation: to combat humidity, install ventilation grilles (vents) on the walls, or use passive dehumidifiers. These accessories are common and inexpensive.

Points of vigilance and pitfalls to avoid

Buying a used container involves some risks. Here are the main points to watch:

• No watertightness guarantee: some sellers offer "as is" containers without guarantee. If you store sensitive goods, require a Wind & Watertight or Cargo Worthy guarantee.
• Hidden repairs: a container may have been repaired with poor-quality materials. Inspect welds and patches. Professional repair is acceptable, but a rough repair can lead to leaks.
• Perforating rust: surface rust is not serious, but perforating rust weakens the structure. Probe suspicious areas with a screwdriver or punch.
• Rotten floor: a soft or delaminated floor must be repaired or replaced. The cost can be significant.
• Missing or expired CSC plate: if you plan maritime transport, a valid plate is mandatory. For static use, it is not a blocker, but it may indicate a lack of maintenance.
• Abnormally low price: be wary of too-attractive offers. A container in good condition has a price consistent with the market.

At Transport Hosni Conteneur, in Marseille, we offer revised and inspected used 20-foot Dry containers, with a Wind & Watertight guarantee. We can assist you in choosing the model suited to your needs, whether for storage, transport, or a conversion project.

Conclusion

The used 20-foot Dry shipping container is a durable and versatile investment. It is suitable for many uses, from simple secure storage to modular conversion, including general cargo transport. Its compact format, Corten steel structure, and marine plywood floor make it resistant, repairable, and scalable equipment. Before buying, check the general condition, watertightness, and regulatory compliance, and do not hesitate to call on a professional for inspection and maintenance. Whether you are a building professional, an industrialist, a retailer, or an individual, we can guide you to the most suitable solution.