How to Keep Moisture Out of Shipping Containers


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When it comes to preparing shipping containers for transport it is crucial that you are able to keep the goods inside of those shipping containers safe.

After all, you’re likely going to be docked a portion of your payment for transport if the goods arrive in less than usable condition.

So, it’s crucial that you know how to prevent condensation in a shipping container. This occurs by stabilizing the air space inside to the air outside and decreasing moisture.

Why Shipping Container Condensation Matters

Shipping containers are entirely watertight by nature, preventing moisture from getting in directly through rain or water.

Because of the way that they are made there should not be cracks or holes in the shipping container through the process of production.

Unfortunately, ambient moisture can be a problem. Dew point temperature can easily lead to condensation. In fact, excess moisture from temperature shifts can allow for the side walls to develop condensation frequently.

When you get that condensation inside a shipping container it will result in damage to the goods that you are shipping as the moisture content continues to rise. This is why you need to stop condensation before it occurs.

But there is more than just that.

The Danger of Poor Shipping Container Ventilation

If a shipping container does not have any means of ventilation it can cause an increase of moisture on the inside, which could cause rusting and mold on the shipping container as well as the goods being transported.

This could result in the goods being unsuitable for use, which is why you need to stop condensation in the first place. Also, lack of ventilation can result in overheating inside the shipping container.

This could mean that a fire or even an explosion could occur inside of shipping containers storing anything flammable. The risk of this is even greater in cases where the container is exposed to high temperatures.

Finally, lack of ventilation means that toxic chemicals stored inside of the container could accumulate in the air. When the shipping container is opened, these fumes could be hazardous to those in the area, or even to the environment.

The good news is that there are several ways to stop condensation, overall moisture, cargo damages, and other problems associated with a lack of ventilation. As long as you know what you are doing, of course.

Ways to Prevent Shipping Container Condensation

Luckily, there is something that you can do when it comes to preventing shipping containers from developing condensation.

Shipping container vents are a great way to make sure you have more control inside and outside the containers you are shipping. They also allow for better control of the temperature inside and more varied container use.

Installing Roof/Side Vents

One of the first things that you can do to improve ventilation and reduce the risk of moisture damage is to install roof vents. Another option for your shipping container is to install side vents.

Some may prefer to do both of these at the same time to increase ventilation even further or you could choose to install one or the other. Either of these can balance the temperature inside and reduce moisture buildup.

You will need the right tools for the job. This process is relatively simple but requires the right tools and process.

  • Safety goggles
  • Protective gloves
  • Earplugs
  • Ceiling/roof vent
  • Circular saw
  • Measuring tape

Prepare Yourself

If you are installing roof vents you will want to gather all of the materials listed above and make sure that you are wearing full protective gear. This will allow you to safely cut through the metal of the shipping container without injury.

Measure Twice

You want to carefully measure the vent that you are going to install so that you know how large to cut the hole into the top of the shipping container. Make sure you measure more than once and measure both the length and width of the vent to make sure you can get the right size before you begin cutting.

Make a Plan

Set your plan for exactly where you will cut the holes to install your roof or side vents. Keep in mind that side vents do best when directly across from each other to allow a cross-breeze. You will need to measure and mark the sides of your shipping container to be sure you have the right placement for these vents.

Cut Your Vents

This is where you will finally cut the holes in the roof or sidewalls of your shipping container to install the vents. You will need to be very careful about cutting straight lines and creating a perfect rectangle or square depending on the shape of the vent you have selected.

Install Your Shipping Vents

Finally, you will install the vents into the holes that you have created in the shipping container. In some cases, you may be able to simply leave the holes open rather than putting in actual vents. In most cases, however, vents provide you with airflow but keep out unwanted pests including birds and excess moisture from rain or waves.

Alternative Options for Decreasing Temperature Differences

There are several other things that you can do when it comes to reducing temperature fluctuations and condensation within containers.

  1. Use Dehumidifiers – Dehumidifiers, like this Honeywell option, can be a great choice because they suck the humidity out of the air and make sure that the interior of the container stays dry. It’s important that you get a dehumidifier that is able to work in the specific conditions that you have however. A dehumidifier that is too small will not be able to keep the entire container dry and could short out or have trouble on its own.
  2. Use Desiccant Pads – Desiccant pads like Dry It are similar to a dehumidifier but they don’t require you to have any form of power. A desiccant pad can simply be placed inside the container (though you may want several) and will then help absorb moisture whereas a dehumidifier will require electricity. Other desiccant products like Dry Packs can help as well. You just hang it up inside the container and it will absorb moisture.
  3. Install Air Conditioning – Yet another option is to install air conditioning within the container. This will take a decent amount of work and construction, but will create a long-term solution for the problem. It will keep temperatures stable and make sure that the flooring and the ceilings are not damaged by moisture as well as protecting the cargo inside the container.
  4. Install Container Insulation – This can take the form of standard insulation or spray foam, but it does require professional installation to make sure that it is done correctly. You want to make sure any insulation you use has the right R factors to protect the cargo that you will be transporting.

    Not all insulation is made the same way and you want to be sure the insulation you choose will work for your conditions. Spray applicators will generally be the easiest solution for most users.

Frequently Asked Questions

What Temperature Does My Shipping Container Need to Be to Stay Above Dew Point?

Unfortunately, there is no set temperature at which you reach the ‘dew point.’ You would need to monitor the weather conditions in order to know what the dew point is on any given day so that you could make sure that your shipping container is above that number.

In general, the dew point is the temperature at which the air around you is saturated with water and would release condensation if the temperature were to change.

What Happens if I Do Not Prevent Condensation Inside the Container?

If you do not prevent condensation within the container when shipping you could increase the moisture content of the shipping container to such an extent that the amount of moisture damages the cargo inside the container.

Too much moisture could also damage the shipping container itself by causing the development of mold or even rust, which can cause the shipping container to break down over time. This can result in even more damage to the items inside the container as well.

What Does Condensation Look Like Inside or Outside of the Container?

If you have any type of condensation in your shipping container you will notice that the container walls are damp. You may feel warm, moist air or you may see droplets running down the sides of the container. You may even see what appears to be container rain.

If you see container rain it means you have a serious shipping container condensation problem and you need to find a way to stop condensation immediately to prevent serious damage to the goods and the shipping containers.

Is it My Responsibility to Prevent Condensation in a Shipping Container?

It is absolutely the responsibility of shipping companies to make sure that the goods they are transporting are protected.

Preventing condensation in a shipping container is part of the responsibilities that you take on when you take the goods from a customer and agree to transport them to another location.

By not preventing condensation in a shipping container that is entrusted in your care you could damage your own reputation and future in transporting additional storage containers for clients.

Wrapping It Up

The bottom line is that you need to keep humidity and the amount of moisture in the storage container as low as possible, to make sure all goods being transported are kept in optimum condition.

With any of the methods discussed above, you can make sure that any container you ship is protected from condensation and moisture from the air.

Ryan Stetson

Ryan Stetson

Currently own two 20' and 40' containers converted into an office/workshop. Having worked in the shipping industry for 6 years, my goal is to share my personal experiences as well as connect potential container buyers with suppliers around the US.

  • container addict
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