FAQ 2: The structure, floor, watertightness and ventilation of containers

What are containers made of?

Shipping containers are primarily built out of weathering steel, or corten steel. Corten steel is used in bridges, chimneys, containers and other structures that need to cope with rough handling and harsh weather. The structure of a shipping container is usually a solid, self-supporting steel structure with eight corner pieces. A general ISO standard (ISO 1161) has been regulated for corner pieces, so finding spare parts is easy.

The floor of the container

The floor of the container is usually built out of plywood sheets that are attached directly to the cross members beneath the container, and are thus quickly replaceable. The thickness of the floor varies depending on the container and its load-bearing capacity. Termite resistant hardwood veneer or Bambo is often used for flooring.

Kontin lattia uusittu
Old and replaced floor panels
Watertightness of the container

Shipping containers are built to be completely watertight. This is achieved by the rubber gaskets fitted into the container doors. There may be small holes and cracks in the rubber gaskets in used containers, but they can be fixed with minor maintenance procedures.

There is often humidity in the containers due to condensation. This needs to be taken into account especially in Finland, where the weather conditions vary a lot. Humidity can be reduced with special air dryers designed for containers and/or separate heating.

Ventilation in the containers

Normal shipping containers have two ventilation holes. Even a small drift of air will help to keep goods dry in a container, and ventilation can be enhanced for example with the following methods:

  1. Building a vent or a ventilation hatch.
  2. Drilling holes to the upper part of the back wall and the lower part of the door of the container (or vice versa), which allows air to move in the container.
  3. By making a small hole to the back part of the container and installing a ventilation fan that works for example with electricity or batteries.
  4. The floor of the container is about 12 cm above the ground thanks to its steel frame, but over time it sinks into the ground. This is why it is a good idea to place for example cinder blocks beneath the container, so that the container is lifted from the ground and air can move around better, also beneath the floor.
Konttien ilmanvaihto
Examples of standard ventilation

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