What to do if my shipping container gets damp should be a rare question. After all, shipping containers are built to carry goods safely across the world’s oceans, enduring extreme weather and rough handling whilst keeping their contents secure and shielded from the elements.
It’s easy to assume that they’ll always stay completely dry inside, and in most cases, they do. If containers weren’t reliably watertight, they wouldn’t be trusted to move valuable cargo across the globe, nor would so many people be converting them into offices, shops, and homes.
However, despite their robust design, shipping containers can still develop damp issues. So, on the off chance this occurs, what to do if my shipping container gets damp? In this article, we’ll explain what causes damp in containers and share practical tips on how to prevent and treat it.
Dampness inside a shipping container is usually the result of condensation forming on the roof. This happens when warm air inside the container cools, often overnight, causing the moisture it holds to turn into water droplets. As the heat escapes upwards, these droplets collect on the ceiling and eventually drip down onto the items below.
The following will increase the likelihood of condensation in your container, causing dampness:
Temperature Fluctuations: If you are regularly opening and closing your container, especially during the cold winter months, moisture in the air can get trapped inside and eventually turn into condensation.
Damage: Over time, damage can occur to containers that will affect how watertight they are. Rainwater can leak through cracks and holes in the roof and walls, allowing moisture inside. This should only be a problem with older containers that have seen plenty of wear and tear, and such damage can be repaired to ensure that your container is water-tight again.
Damp Items: Storing items in a container that aren’t completely dry can cause condensation. Damp clothes, garden furnishings that have been exposed to the rain, and household appliances that rely on water, such as washing machines, can cause dampness when stored in a container. Also, if you load goods into your container during a rainstorm, the wetness on the items will evaporate into condensation when the temperature in your container rises.
The less heat that escapes from your container, the less condensation will form inside. Here are a few effective ways to reduce dampness:
Keeping your container well aired and ensuring the temperature inside is as similar as possible to the temperature outside will reduce condensation. During warmer weather, it’s a good idea to leave your container open to the elements and let any dampness dry out.
Insulating and lining the container is widely seen as the most effective way to prevent condensation. Ply, melamine, or dry-box lining can be fitted to the interior walls, particularly the ceiling, with insulating materials such as rock wool or Celotex filling the gap between the inner lining and the container’s steel shell. This creates a thermal barrier that helps to maintain a steady internal temperature, keeping the walls and ceiling dry.
Containers with this type of lining already installed are typically more expensive than standard units, and costs will rise with the thickness of the ply used. However, they provide a high-quality, long-term solution that can prevent condensation issues for up to 10 years.
If you need to keep your container closed for an extended period, you might want to consider installing air vents. The louvres in these vents will increase the airflow inside your container, allowing contents to stay dry and avoid damp.
There is, however, a risk of small insects gaining access through the vents. The smaller the vent, the less chance of bugs getting in, but the lower the quality of ventilation.
At Upminster Containers, our units all have a minimum of 6 vents, but usually more, and we offer ventilation with all of our converted containers as standard. Ventilation options are always worth checking if you’re purchasing from another provider.
Many consider Grafotherm Spray to be the industry-standard treatment for condensation, and it’s something that we offer here at Upminster Containers upon request. You’ll need to carefully apply this textured coating to the ceiling of the container and give it a few days to set.
It will absorb much of the condensation and speed up moisture evaporation. It’s fair to say that Grafotherm isn’t the nicest material in the world, so take care if you’re doing the work yourself. And make sure that no items in your container come into contact with it.
The more tightly packed your container is, the less room there is for air to circulate and potentially form condensation. So, using as much of the space in your container as possible is a good way to reduce dampness.
Whilst it might seem protective, wrapping furniture in plastic can actually trap moisture against the surface, preventing it from evaporating. This can lead to condensation forming inside the wrapping, which encourages mould, mildew, and wood rot. Instead, use breathable covers such as cotton sheets or moving blankets to protect furniture, whilst still allowing air to circulate.
There are a few different brands of rectangular plastic sticks on the market, each of which is filled with a salt-like substance called desiccant calcium chloride. These sticks hang inside your container and absorb any moisture in the air. They can hold up to 2 litres of water in their built-in tank, but this will need emptying when full.
It’s recommended that two damp sticks be installed to keep a 20ft container condensation-free, and double that amount for a 40ft container. Sticks are non-toxic, and each provides up to 3 months of condensation control, so they will need to be replaced after this time expires.
These are available directly from Upminster Containers, and we will be able to advise whether they are the right option for you.
Refrigerated containers offer a high level of insulation that can protect against condensation. So even if you don’t switch on the refrigeration, your contents will be more damp-proofed than if you buy a standard container.
If you can connect a power supply to your container, a de-humidifier offers a good option for removing condensation-causing moisture from the air. But as with all electrical appliances, you’ll need to keep an eye on it and empty the water tank regularly.
We hope this blog helped answer ‘What to do if my container gets damp?’. In this circumstance, we advise giving us a call. But there are plenty of preventative measures you can also take to avoid dampness.
Our family run business has been helping customers across Essex and London with their shipping container needs since 1968.
If you want to hire or buy a damp-proof shipping container, or would like help with reducing the dampness in your existing shipping containers, give us a call. We’re happy to answer any questions that you may have.
