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How to Prevent Shipping Container Condensation

One of the main issues that affects shipping container units is ‘sweat’ or condensation. This is caused when two different temperatures meet. It usually occurs during the night, when the unit cools and heat escapes through the roof. This causes a layer of sweat to form when the moisture in the air condenses against the cold surfaces of the box. Some sweat is to be expected, although too much moisture can damage the contents of your unit and cause issues such as mould and mildew. If you are worried about your shipping containers sweating and damaging your unit or goods, then here are some simple ways to prevent sweating.

What Causes Shipping Container Condensation?

Shipping container condensation, or shipping container sweating, is caused by temperature fluctuations, high humidity and inadequate ventilation inside the container. Condensation forms in the following way:

  • When humid air inside the container cools, it causes moisture to condense on the walls and ceiling of your container. 
  • This condensation may run down the walls of your container.
  • This can lead to problems such as mould or mildew if you’re not careful.

Additionally, if your container travels through different climates, the change in temperature can cause warm, moist air to condense. And if the container isn’t well ventilated, humid air may become trapped inside – which can further exacerbate the condensation.

If you’re loading damp or wet goods into the shipping container, this can also introduce excess moisture into the air, which may make shipping container condensation worse.

How to Manage Condensation in Shipping Containers

There are plenty of ways to stop condensation in a shipping container. It’s first crucial to understand what is causing your shipping container condensation problems – and once you know that, the next step is to learn how to eliminate sweat in containers.


Vents are installed in all standard units to ensure ample airflow while still keeping the unit watertight. In most cases, proper ventilation is sufficient to manage sweating. However, you may need to take additional measures to prevent shipping containers sweating if you have significant sweat forming in your unit. If you are placing boxes next to each other, then ensure that you don’t accidentally cover the vents. Obscuring vents will reduce airflow and is likely to lead to an increase in sweating within your unit.

Anti-Sweating Coating

Anti-sweating coating – also known as Grafo-Therm Anti-Condensation Paint – can be applied to the interior of your unit to help prevent sweating. Generally, the paint is applied to the roof of the unit, along with the top six inches of the interior sidewalls. Anti-sweating coating is designed to provide extra insulation and absorb excess moisture in the air. This helps to reduce sweating from forming on your units interior. 


Dehumidifiers extract excess moisture from the air to help prevent sweating from forming in your unit. A dehumidifier requires electricity to operate and so you need to have access to a nearby power source. The collected water must be removed from the unit regularly to prevent it from being reabsorbed back into the air. Some dehumidifiers have an automatic on/off feature which uses sensors to detect moisture in the unit.

Moisture Traps

Moisture traps work in a similar way to dehumidifiers, but they are a cheaper option and have minimal costs once installed. There is a good selection of moisture traps available to purchase. For instance, moisture capture crystals extract moisture from the air and transform it into a solution that can then be collected from the tray and disposed of. You simply refill the tray with new crystals to keep dampness at bay. Moisture crystals are a simple and cost-effective way to combat sweating and extend the lifespan of your unit and goods. This will help to ensure that you get the maximum return on your investment.

Container Lining

Another way to prevent shipping containers sweating is by using container lining. This can be added to the inside of your container to help prevent condensation drops from forming. The lining essentially absorbs the excess moisture in the air, meaning it can’t then cool when it meets the outside wall.

Container linings include boards that not only reduce the moisture in the air, but also have insulating properties that reduce the drastic temperature differences – meaning your container is less likely to suffer from condensation. You can also purchase anti-condensation coating, which can be applied to the surface of the roof to help absorb moisture and reduce condensation.

Still have questions about sweat in containers?

If you have sweating in your unit, then it is important that you address the issue and take anti-sweating measures to protect your unit. Luckily, there are plenty of things you can do to manage the risk of sweating and extend the lifespan of your unit and belongings. We are one of the UK’s largest suppliers of shipping containers and have over 40 years of experience selling, hiring and converting units. Our team can provide expert guidance with most applications and queries relating to storage units. You can give our specialist team a call to discuss your requirements, get a quick quote or view our range online.

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0800 1954 538