Control the Moisture Levels in Your Storage Container
If you are storing items in a standard shipping container that is placed outside and exposed to the elements your goods are susceptible to condensation occurring inside the container, usually collecting on the ceiling. The root cause of moisture damage in storage containers is the simple fact that warm air can hold more moisture than cold air just like the dewy grass in the morning after a cool summer night. A shipping container is a metal box that is quickly affected by ambient temperature changes. When the container is warm, the atmosphere inside the container can become humid. Moisture gets into the air in the container from the outside or by evaporation from the cargo. When cooled during the evening, water droplets will form, usually on the coolest place like the ceiling, when then the droplets are large they drip onto your stored items. If this is not addressed, you will get a micro rain cycle, causing water damage on your stored items.
No container is air tight; it will “breathe” as a result of temperature cycles. When the air inside the container
cools, the pressure drops. Air and moisture moves in from the outside to equalize the pressure. The opposite happen when the air inside the container heats up, but it is easy to show how a repeating cycle of breathing can cause a buildup of moisture inside he container, especially if there is absorbing packing materials.
Before you store your items in a shipping container, check the interior is dry, check that it has no holes in roof or side walls. Get someone to shut you inside, allow your eyes to adjust to the dark and slowly with one hand on a side wall, move to rear of container across and back to doors, if there are any holes they should quickly become apparent. Check to see that the container door seals are secure and weather proof. They are a dual seal, the outer flange prevents water getting in by wind or wave, the inner seal prevents any water that may have passed the first seal entering the container. Should that happen, it sends that water by drainage around the door frame to drain out of bottom, so check the top and side seals and make sure they are free and clean.
Our research has discovered a product called Jet Chemical 01-1015 Dry Out Dehumidifier to help reduce the moisture content inside of storage containers; several of these should be set in the interior of your container. We recommend initially placing at least two cans of Jet Dry Chemical Dry Out in a 20’ container and ideally they should be placed equal distance apart in the container. If your storing for a long time you will need to check and exchange the used Jet Chemical Dry Out cans every three to four months so you should place them close to the doors.