Are Shipping Containers Waterproof?

The other day I noticed a 20-foot shipping container at a construction site, and it got me thinking, are shipping containers really watertight? So, I did a little research, and this is what I discovered…

So, are shipping containers waterproof? I found out that most shipping containers are indeed waterproof. For a container to remain waterproof, the door seals need to be in good shape, and the container needs to be free from holes.

The door seals need to be intact and free from splits. A damaged door seal can allow water inside the container. Also, you want to inspect any rust spots to see if any holes have developed in the container. Ideally, you want to remove rust and then apply primer and paint.

Damaged shipping containers can leak

When you go shopping for a container you need to make sure it has no holes. A hole even a tiny one will allow water to enter the container.

It’s common for containers to develop leaks during their long lives. A container can last over 20 years at sea.

You can find larger holes by doing an exterior inspection of the container. It’s best to get on top of the container to examine the roof. You will probably need a 10-foot extension ladder to do this.

You also want to examine and identify any holes in the container doors. The doors are usually the most common place that leaks develop.

Are Shipping Containers Waterproof
Inspect doors for potential leaks

After you complete an exterior inspection, you now want to examine the interior…

You can do an interior inspection for leaks by partially closing the container doors. If you see any light shining through, you know the container is not waterproof.

You want the container seller to repair all holes before you purchase it. If a repair is not possible, you may want to look at other containers for sale.

Fixing holes in containers can be expensive because they require welding to repair them properly.

Old worn out door seals can let water into the container

Before purchasing a container, you want to spend some time inspecting the container door. The door should be relatively easy to open, and the seals around the door should be in good shape.

The cargo container doors will require a little force to open, but an average-sized adult should be able to open the doors quickly. If the doors are tough to open you may ask to have them repaired, or you can look at other containers.

The seals around the container doors keep out rain and seawater. This heavy-duty rubber should be firm and free of cracks. An older seal usually dries out and splits.

You want to look for a container that has a good seal because this prevents water from entering your container. The seal will also keep rodents out of your container.

Should you buy a one-trip or an older cargo-worthy container?

You may want to purchase a one-trip container if you plan to use it as a home. An older cargo-worthy container would be ideal for a shed and possibly a garage.

You will pay more for a one-trip container because it is in much better shape. A cargo-worthy will have more dents and scrapes, and because of this, they are more prone to leaking.

The cargo-worthy containers that are for sale have made many trips at sea. A lot of these containers may have travelled around the world multiple times.

Cargo Containers At Sea
Shipping containers on a cargo ship

One trip containers have minimal dents and scrapes, so the chances of them being waterproof are very high.

Before you purchase a one-trip container, you want to try to get a copy of the containers shipment manifest. This document will reveal the contents of the last shipment. You want to try to avoid purchasing a container that contained toxic materials.

The newer one trip containers usually come with a 5-year warranty. You want to find out what the warranty covers before purchasing a container. A good warranty should protect you against paint defects and leaks.

Most suppliers usually inspect the containers before selling them. A reputable supplier should have a guarantee that states that the container is waterproof at the time of purchase.

It’s always important to do an inspection regardless of what the supplier claims. You don’t want to have a container delivered to your property only to find out that it leaks.

How to prevent condensation inside the container?

Keeping moisture from entering your container is very important. So you want to treat any rust spots when you notice them. Doing this preventive maintenance will keep your container free from leaks.

Unfortunately, moisture can still get inside your container without a leak. And this happens because of condensation build up…

Condensation is always a problem with containers. This condensation buildup usually occurs on the ceiling and the top six inches of the interior walls.

This buildup of moisture occurs when a temperature difference exists between the external environment and the inside of the container. This moisture can damage the contents of a container. Excess humidity can also cause rust to form over time.

If sweating or condensation build-up is a problem, you can do a few things to keep the moisture out.

Do you plan to use the container as a home?

If so you can do the following… Installing a vapour barrier inside your container will prevent condensation from forming. The vapour barrier is usually pretty easy to install, and you should be able to complete the project in a few short hours.

It would probably be a lot easier if you had an additional person to help you install the vapour barrier.

You will also want to install insulation that is suitable for your environment. A dehumidifier will also help keep the moisture levels down.

Do you plan to use a container for a shed or a garage?

If so, you can take the following precautions to eliminate moisture in your container shed and garage…

Desiccants eliminate the condensation buildup that occurs on the inside of containers. The desiccant pouches will protect the contents of the container from mould, mildew, rust, and corrosion.

If you don’t have access to desiccants, you can also use a bag of cat litter. The litter usually does an excellent job of removing the excess moisture from the environment.

In conclusion

I hope you now understand what makes a shipping container watertight. And you should have a good understanding of what to look for when purchasing a shipping container.

If a supplier is trying to sell you a cheap second-hand container, it may no longer be waterproof. You can usually get excellent deals on containers that are no longer waterproof.

If this is the case, you should avoid these containers because it can cost a lot of money to make them waterproof again.

You may want to consider going shopping for a container during a rainstorm. You may find this inconvenient but its a perfect way to quickly detect leaks in a container.

P.S. Are you planning to purchase a shipping container? If so, what will you be using it for? Let me know in the comments below…

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