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How To Protect Your Shipping Container From Condensation

30 April 2024


Tips & Guides

Shipping containers are an indispensable part of global logistics, serving not only for cargo transport but also as storage and even living spaces. However, they often face the challenge of condensation due to temperature changes and humidity. This phenomenon, known as “container rain,” can severely damage the contents stored inside, leading to mould, corrosion, and other moisture-related issues. 

Recognising and addressing shipping container condensation is crucial for protecting the items inside and extending the container’s lifespan. We’ll explore effective strategies to prevent condensation, ensuring your container stays dry and secure regardless of the weather conditions.

What is shipping container condensation?

Shipping container condensation, or “container rain,” occurs when warm, moist air inside the container cools to its dew point, causing moisture to condense into water droplets. This condensation commonly collects on the container’s ceiling and walls and can severely damage the contents if it drips onto them. 

Given the range of items that can be affected – from electronics to textiles – understanding how and why this moisture accumulates is key to effectively preventing and protecting the items stored within the container.

What causes shipping container condensation?

Several factors contribute to the formation of condensation inside shipping containers, each playing a role in the overall moisture management of these units:

  • Temperature Fluctuations: Fluctuating temperatures within the container, such as those experienced from day to night or when moving between different climates, can cause the air inside to reach its dew point, resulting in condensation. This is because cooler air holds less moisture than warm air, and excess moisture condenses into water droplets.
  • Air Space: The amount of open space within the container affects moisture accumulation. Large, open spaces inside a container can hold more moist air. As more air space is available, it becomes easier for moisture to accumulate, increasing the likelihood of condensation.
  • Inadequate Ventilation: Proper ventilation helps to equalise the temperature and moisture levels inside and outside the container, preventing the buildup of moist air. Without adequate ventilation, moisture remains trapped inside, which can lead to condensation especially when there is a significant temperature difference between the interior and exterior of the container.
  • Cargo Moisture Content: Cargo with high moisture content, such as paper, cardboard, wood, and chilled foods or beverages, increases the likelihood of condensation. These materials can absorb and release moisture into the air, contributing to moisture buildup within the container.
  • Container Usage: How a container is used also affects condensation. These include how often doors are opened, the frequency of loading and unloading activities, and environmental conditions during loading. Each of these elements can alter the internal climate of the container, affecting condensation levels.

What problems can condensation cause a shipping container?

Condensation inside shipping containers can cause significant problems by damaging both the container and its contents. When moisture collects and condenses, it leads to rust and corrosion on the metal walls and floors of the container, weakening its structure and reducing its lifespan.

Unfortunately, although it may seem like a bit of water on the sills might not be a big issue, the damage that can be caused by condensation can result in large repair costs and detrimental damage to your container. 

How does condensation damage a shipping container?

Moisture buildup leads to rust and corrosion on the container’s metal surfaces, weakening its structural integrity and reducing its lifespan. The contents inside the container are also at risk; electronics, textiles, and furniture can develop mould and mildew, damaging them and potentially causing health issues.

Additionally, the damp environment created by condensation can also attract pests such as insects and rodents, which can cause additional damage.

rusted shipping container

If you spot any of the following signs of condensation below, it is vital that you contact a shipping container specialist to assess the extent of the issue:

  • Material staining
  • Equipment damage
  • Water on windows or walls
  • Metal damage
  • Slip hazards
  • Coating & adhesive damage
  • Mould growth and mildew
  • Poor insulation performance

However, if you believe your container to be condensation-free, then make yourself aware of these tell-tale signs to avoid any unnecessary future repairs.

How to measure shipping container condensation levels

To test for condensation in your container, examine the interior surfaces for any moisture on walls, windows, or other areas. Minor condensation might be manageable with basic preventative measures. If the problem persists, consider consulting a specialist for a comprehensive assessment and solution.

Another method to check your shipping container for condensation involves comparing the temperature, relative humidity, and dew point inside the container with those outside. Use a digital thermometer/hygrometer to measure these factors. This comparison will help determine if conditions inside are prone to condensation, enabling you to implement preventive measures accordingly.

How to stop condensation in a shipping container

To stop condensation in shipping containers, you can implement several key strategies to protect both the container itself and its contents from moisture-related damage. These methods aim to protect the container and its contents from moisture damage by choosing suitable materials, using technology to control humidity, making structural adjustments and adopting specific packing and maintenance practices.

Choose the right pallets

Choosing the right pallets is essential in preventing condensation within shipping containers. Wood pallets are most commonly used, but they must be dry and treated to prevent them from absorbing and releasing moisture back into the container. 

However, pallets made from materials like plastic or treated wood are preferable because they are less likely to absorb and retain moisture compared to untreated wood pallets. 

Ensuring your pallets are in good condition and appropriate for your cargo type can significantly reduce the risk of moisture damage.

Use desiccants

Desiccants are materials that absorb moisture from the air. They work by chemically binding water vapour from the surrounding environment, effectively reducing humidity levels. 

Common desiccants include silica gel, calcium chloride, and clay. These are often placed in sachets or containers within shipping containers to protect goods by maintaining a dry atmosphere.

Consider moisture traps

Moisture traps, on the other hand, are devices designed to physically capture and collect excess moisture from the air. They often consist of a container filled with a hygroscopic (moisture-attracting) solution or material that condenses and collects water. 

Moisture traps are typically more passive and can handle larger air and moisture volumes than desiccants. They are commonly used in residential and commercial settings to control humidity.

Need more ways to eliminate dampness in your container? Check out our practical Damp Sticks, designed to tackle rising damp and moisture in shipping containers and other storage areas!

Install dehumidifiers

Dehumidifiers work by removing moisture from the air and collecting it in a container or expelling it through a hose. This method is especially beneficial in environments where humidity levels are consistently high or when transporting moisture-sensitive goods.

To get the best results, select a dehumidifier with a capacity suitable for the size of your container and ensure regular maintenance to keep it functioning efficiently. This approach can significantly reduce the risk of moisture damage to the contents of the container.

Insulate your container

Insulating your shipping container is a key step in preventing condensation by stabilising the internal temperature and reducing the occurrence of temperature fluctuations that can lead to moisture buildup. Common insulation materials include foam boards, spray foam, and fibreglass, each offering different levels of thermal resistance and moisture control.

By properly insulating the walls, ceiling, and floor of the container, you not only maintain a consistent climate but also enhance energy efficiency if heating or cooling is used within the container. Ensure that the insulation is properly sealed to eliminate any gaps that might allow moisture and air leaks, maximising its ability to control condensation. 

Install additional vents

Installing additional vents in a shipping container is a practical way to enhance air circulation and reduce moisture buildup, which can lead to condensation. Vents help equalise the air pressure and temperature inside and outside the container, allowing damp air to escape and fresh air to enter. This natural airflow helps to dry out the internal environment and keeps it dry. 

For best results, it’s important to strategically place the vents to promote optimal air exchange; typically, one vent is placed near the top of one end of the container, and another at the bottom of the opposite end, creating a cross-flow of air. This setup can significantly reduce the risk of condensation affecting the container’s contents.

Ventilate your shipping container

In addition to installing vents, ventilating your shipping container effectively can be done by using mechanical aids like fans or simply opening doors during loading and unloading to promote air exchange.

Good ventilation helps to expel moist air and bring in drier air, effectively lowering humidity levels inside the container. Effective ventilation not only helps in reducing moisture but also prevents the buildup of odours and the growth of mould and mildew, protecting both the container and its contents.

Look for container damage

Regularly inspecting your shipping container for damage can help prevent condensation issues. Damage such as cracks, holes, or compromised seals can allow external moisture to enter, which increases the risk of condensation inside. 

Pay special attention to the container’s doors, roof, and joints, where damage is most likely to occur. Any signs of rust or corrosion should also be addressed immediately, as these can weaken the container’s structure and worsen moisture problems. 

Repairing any detected damage not only helps in maintaining the container’s integrity but also significantly reduces the chances of moisture penetrating and accumulating inside.

The bottom line

Effectively managing and preventing condensation in shipping containers is crucial for safeguarding both the container’s contents and its structural integrity. By implementing strategies such as adequate insulation, ventilation, the use of desiccants, and conducting regular inspections for damage, you can significantly mitigate the risks associated with moisture-related issues. 

Understanding the root causes and taking proactive measures to control condensation not only protects your cargo from damage but also extends the lifespan of the container while reducing unnecessary expenses. Just as you would care for your home, it’s important to take the necessary precautions to safeguard your shipping container against elements that can cause significant harm and expensive repairs. 

Remember, the key to effective condensation management lies in consistent upkeep and timely intervention, guaranteeing the continued efficiency and dependability of your shipping containers.

Helpful? We certainly hope so! If you would like to discuss an idea for a shipping container conversion with us, or you’d like some further pointers or professional tips to adequately protect your current container against condensation, please contact the Universal Containers team on 0845 050 0330 or email for friendly, no obligation advice.

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