What is condensation?

2 Definitions of Condensation:

  • Atmospheric moisture that has condensed because of cold
  • The process of changing from a gas to a liquid or solid state.

Condensation in Shipping Containers

Condensation can occur within 8ft, 10ft, 20ft and 40ft shipping containers, but it occurs mainly on the roof interior and top 6 inches of the interior side-walls. The moisture can generally be from storing damp or wet goods inside the container along with high and low temperatures outside the shipping container.

In order to correct this, the shipping container needs good ventilation and be dehumidified.


Container vents are 10 holes punched into the steel wall with an external bracket over the top to enable good airflow, but still keeping the container watertight.

When you see a typical shipping container fitted with vents you will usually notice the vents are located on each side of the unit, just below the top rail. With a second hand unit, they generally have 2 or 4 vents. With a new build shipping container, they can either have 4, 8 or 10 vents. Some of the new containers come with vents on the side only or on the doors and the opposite wall. The vents are positioned approx.. 6 inches below the top rail of the shipping container.

As long as the container is filled with bone dry goods/equipment then the storage container should be fine closed up for at least 2 years, if not longer.

If you need to access your storage container, as many of you do, then this is when condensation can occur. If the weather is particularly cold and misty when you open the unit and then you close the doors, the weather can bring on condensation.

If you think the container has insufficient vents, then we can fit more for an extra cost.

Anti-condensation coating

Anti-condensation coating is a coating sprayed onto various surfaces, in this case corrugated steel surfaces, which can insulate the storage container and retains some moisture. This is a long term solution, proving it to be inexpensive compared to some of the other solutions.

This anti-condensation coating is typically applied to the container roof interior and the top 6 inches of the interior side-walls using spray applicators. This only works as long as the doors are opened on a regular basis, so the moisture can be expelled from the shipping container.