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 is a versatile and cost-effective storage and transport solution. Coming from the international maritime fleet, it has already proven its sturdiness and ability to withstand the harshest conditions. Choosing a refurbished used model gives you a Corten steel structure and controlled watertightness on a tight budget, while contributing to the reuse of durable industrial equipment.

Whether you are a construction professional, farmer, logistics specialist, or individual, this container meets many needs: secure storage, technical room, site office, self-storage unit, or even the base of a modular housing project. Before you start, it is essential to understand its features, limits, and the points to check for an informed purchase.

Technical Specifications of the 20-Foot Dry Container

A 20-foot Dry container complies with ISO 668 and ISO 1496 standards, which define its external dimensions and structural strength. Here are the standard specifications:

• External dimensions: approximately 6.058 m long, 2.438 m wide, and 2.591 m high.
• Internal dimensions: approximately 5.898 m long, 2.352 m wide, and 2.393 m high.
• Internal volume: approximately 33 m³.
• Tare weight: generally between 2,200 and 2,400 kg.
• Maximum payload: up to approximately 28,000 kg.
• Maximum gross weight (MGW): commonly 30,480 kg.

These values may vary slightly by manufacturer, but they are the reference for this type of container. The structure is made of Corten steel, a low-alloy steel offering better corrosion resistance than ordinary steel. The side and front walls are corrugated sheets, ensuring rigidity and resistance to deformation. The roof is also corrugated steel, and the floor is 28 mm marine plywood, treated to withstand moisture and heavy loads. The double rear doors are equipped with container locking bars and rubber gaskets.

Criteria for Choosing a Used Container

General Condition and Corrosion

When buying a used container, the condition of the structure is paramount. Surface corrosion is normal and can be treated, but perforating corrosion compromises watertightness and strength. Carefully inspect the roof, walls, and bottom frame. Look for holes, deep rust areas, or major deformations.

Wind & Watertight

A container labeled "Wind & Watertight" (WWT) has been tested and certified wind- and watertight. This guarantee means it has no leaks at the roof, walls, or doors. For long-term storage, even outdoors, this is an essential criterion. Check the condition of the rubber gaskets: they must be flexible, without cuts or cracks. Make sure the doors close tightly and the locks work properly.

Floor and Structure

The 28 mm marine plywood floor should be examined for rotten areas, splinters, or sagging. A sound floor supports heavy loads without flexing. Also check for the CSC plate (Convention for Safe Containers) and the BIC identification number, which attest to the container's compliance.

History and Refurbishment

A refurbished used container has generally undergone a technical inspection and minor repairs (gasket replacement, anti-corrosion treatment). Ask whether the container has been tested WWT and whether any work has been done. Regular maintenance extends its lifespan.

Common Uses of the 20-Foot Dry Container

The 20-foot Dry container is used in many contexts:

• Static storage: archives, tools, electronic equipment, furniture, various goods. Its watertight design and lock (with the option of adding a padlock) provide protection against theft and bad weather.
• Construction sites: site office, material storage room, crew changing room. It can be fitted with shelves, lighting, and ventilation.
• Modular housing: conversion into a studio, office, bathroom, or kitchen after fitting out. Its compact volume suits small plots, and its sturdy structure allows stacking.
• Export: transport of goods by sea, road, or rail. It can be stacked and handled with suitable lifting equipment (reach stacker, crane, forklift equipped with a spreader).

Pre-Purchase Inspection: The Essential Checklist

To avoid unpleasant surprises, follow this checklist during the inspection:

1. Roof: check for no perforations, major dents, or deep rust. Make sure water does not pool.
2. Walls: inspect the corrugated sheets for holes, tears, or rough repairs.
3. Bottom frame: examine the longitudinal and cross members for perforating corrosion.
4. Floor: test its solidity by walking on it, look for soft or rotten areas.
5. Doors: open and close the panels; they must pivot without forcing. Check the condition of the gaskets and locks.
6. Gaskets: they must be flexible and without cuts. A cracked gasket can let water in.
7. Plates: make sure the CSC plate and BIC number are present and legible.
8. Watertightness test: ask for a WWT guarantee or perform a water test (spraying) to check for no leaks.

Interior Fitting and Space Optimization

The 33 m³ internal volume lends itself to various configurations. For storage use, installing metal shelves or racks saves height and organizes references. The corrugated walls offer natural anchor points, but it is best to attach shelves to horizontal rails bolted into the upper and lower corner rails, so as not to pierce the sheet and preserve watertightness. Battery-powered LED lighting or lighting connected to an external power supply improves comfort.

For use as a site office, adding insulation (mineral wool panels or polyurethane foam) and interior cladding (plywood or paneling) helps temper temperature variations. Mechanical or natural ventilation (grilles at the top and bottom) reduces humidity and renews the air. If the container is to accommodate personnel, a side access door or window should be provided, along with an electrical supply compliant with current standards.

Condensation and Humidity: Preventing Damage

Condensation is common in metal containers, especially when exposed to large temperature swings between day and night. Relative humidity can rise inside and cause corrosion or mold on stored goods. To limit this risk, it is advisable to use dehumidifiers (electric or salt-based), install moisture absorbers, or ventilate the container. Another solution is to apply an insulating coating to the inside of the roof, the main condensation point. The marine plywood floor resists moisture, but it should not remain in prolonged contact with water; it is therefore important to check for no leaks and quickly clean up any spills.

Comparison with Other Container Formats and Types

The 20-foot container is the smallest standard format in maritime transport, with a length of about 6 m. The 40-foot container is about 12 m long and offers double the volume (about 67 m³). The 40-foot High Cube (HC) adds about 30 cm of internal height, increasing the volume to about 76 m³ and making it easier to store tall loads.

The 20-foot is more maneuverable, easier to move and place on a cramped site. It can be transported by standard trucks without an exceptional convoy in most cases, whereas the 40-foot often requires a longer container carrier. The 20-foot is also better suited to stacking on small sites. On the other hand, the 40-foot offers a better cost per cubic meter for storing large quantities. The choice therefore depends on the volume to be stored, the available space, and transport constraints.

In addition to the Dry, there are Reefer (refrigerated), Open Top (open roof), Flat Rack (no side walls), Tank (for liquids), and High Cube (height variant) containers. The 20-foot Dry container remains the most versatile and economical for most common needs.

Regulations and Transport in France

In France, the transport of shipping containers is subject to regulations on vehicle weights and dimensions. A 20-foot container can be transported by truck, but its total laden weight must not exceed the limits allowed on the road network (generally 44 tonnes for a road train). Exceptional transport may be required for convoys exceeding these limits. In addition, the container must be properly secured on the vehicle, in accordance with road safety rules. For imports, customs duties and taxes may apply; it is advisable to check with the customs authorities.

Installing a container on private land may be subject to planning rules. A container used as a storage room may be considered a construction and require prior authorization (prior declaration of works or building permit) depending on its surface area and duration of installation. It is recommended to check with the town hall before any installation. For temporary use on a construction site, a declaration may also be required. The container must comply with fire safety and accessibility rules if it receives the public.

Care and Maintenance

A used shipping container requires minimal but regular maintenance. It is advisable to clean the roof and gutters to prevent the accumulation of leaves and debris, which can retain moisture and promote rust. Door gaskets should be cleaned and lubricated (with a silicone-based product) to prevent them from drying out and cracking. Locks and hinges should be greased periodically. If rust areas appear, they should be brushed and treated with anti-rust paint. A well-maintained container can last several decades.

Foundations and Installation

A 20-foot container can be placed on level, stabilized ground, such as a concrete slab, concrete blocks, or wooden beams. It is essential that the support be level to avoid any deformation of the structure. If the container is to be stacked, suitable foundations must be provided and safety rules followed. Anchoring to the ground is recommended in wind-exposed areas. For prolonged use, it is advisable to raise the container a few centimeters to allow air circulation under the floor and prevent moisture buildup.

Security and Theft Protection

A shipping container offers superior security to a conventional garden shed. Its steel walls and lockable doors deter intrusions. To enhance protection, it is possible to install a high-security padlock (disc lock type) on the handles, or add an extra door lock. Some container models are equipped with reinforced locking bars. It is also advisable to park the container in a visible or lit location, and to regularly check the condition of the locks. For storing valuables, an alarm or remote monitoring system can be considered.

New or Used Container: Which to Choose?

The question of new versus used comes up systematically at the time of purchase. A new container (often described as "one-trip" because it has been used only once for maritime transport) has flawless aesthetics, perfect watertightness, and maximum lifespan. Its price is, however, significantly higher, generally 30 to 50% above an equivalent used model. A refurbished used container, like the one described here, retains all its structural qualities. Its signs of wear (scratches, small dents, treated surface rust) in no way affect its primary function: protecting your goods from bad weather and intrusions.

The choice therefore depends on three factors: available budget, intended use, and aesthetic requirements. For industrial storage, a site room, or utilitarian use, used is almost always the best compromise. For a visible modular housing project or commercial use requiring a polished image, new or a used container in excellent condition ("like new" grade) may be justified. In all cases, require a watertightness test and a WWT guarantee before confirming the order.

Grades and Classifications of Used Containers

The used market distinguishes several quality levels, often designated by grades. Although there is no universal standard, there are generally three main categories:

• Grade A or "like new": very lightly used container, impeccable structure, paint in good condition, no visible defects. Ideal for aesthetic use or conversion.
• Grade B or "good condition": container that has seen use, with a few dents and superficial scratches, but perfectly watertight and structurally sound. This is the best value for money for most uses.
• Grade C or "standard condition": container more marked by wear, with surface rust and minor deformations, but still functional and watertight. Suitable for utilitarian storage or construction sites.

Whatever the stated grade, a physical inspection remains essential. A grade does not replace a detailed visual examination of the roof, walls, floor, and gaskets. Always ask for recent photos or, better, an on-site visit before purchase.

Preparing Delivery and Receipt of the Container

Delivery of a 20-foot container requires a container truck equipped with a hydraulic arm (roll-off) or an unloading crane. Since the tare weight is about 2.2 to 2.4 tonnes, the vehicle must have sufficient lifting capacity. Before delivery, carefully prepare the location: level ground, clear, accessible to heavy vehicles. Check for any overhead lines (electrical, telephone) that could hinder the unloading maneuver.

On receipt, immediately check the condition of the container against the photos or description provided. Open and close the doors, inspect the gaskets, check for no new impacts from transport. If a problem is found, report it without delay to the carrier and the seller, before signing the delivery note. Once the container is placed, anchor it if necessary and check its level using a spirit level.

Common Mistakes to Avoid When Buying

To conclude this guide, here are the most common pitfalls facing a used container buyer:

1. Buying without inspecting: relying solely on an ad or photo can lead to unpleasant surprises. Require a visit or detailed, recent photos.
2. Neglecting watertightness: a non-WWT container can let water in and ruin your goods. Ask for a written guarantee.
3. Underestimating transport: delivery cost can represent a significant share of the total budget. Find out in advance about the terms and price.
4. Ignoring planning rules: an undeclared installation can lead to administrative complications. Check with your town hall.
5. Forgetting maintenance: a poorly maintained container deteriorates faster. Plan for regular cleaning and anti-corrosion treatment.

Conclusion: A Durable and Functional Investment

The used 20-foot Dry shipping container is a durable and functional investment. Its sturdy design, watertightness, and modularity make it a solution suited to many projects. By taking care to inspect it before purchase and maintain it regularly, you will enjoy secure and economical storage space for many years. Whether you are a construction professional, farmer, logistics specialist, or individual, this container will meet your needs reliably.