Controlling humidity in shipping container

[garagelogician]

My parents have a shipping container on their property in east central MN. They are using it as overflow storage for furniture and other household odds and ends.

The container is tight with no leaks, but it appears that there is some isolated mold/mildew on some items that have been in there for a couple years. MN climate ranges from 90s with dewpoints up into the 70s, down to the 30s below zero.

I know it is important to have air space between items so that they can breathe.

Are the big desiccant packs effective? How often should they be changed out?

Any other ideas?

 

[matt_i]

I have some big bentonite dessicant packs, probably 2-3 lbs each. Shipped in the short ~20' sea container with manufacturing equipment there were probably close to 20 of them, and each thing wrapped in sort of a plastic-lined aluminum foil to build yet another microclimate. This is probably more valuable than furniture...so they weren't afraid to thrown in some extras I think.

I would think about baking them out 2x per year.

Running power to a dehumidifer would be even better.

 

[gunguy]

If near an electrical power source, install a dehumidifier and route the drain to the outside.

Jim

 

[HOTFR8]

I have these on both of my containers.

 

[jfish]

I have these on both of my containers.

Done this on dozens of metal containers. Works.

Now, I have one container that we used for long term document storage. Bankers boxes. I plumbed a vent fan into the back wall on a humidistat, and a space heater. Years and years and not one paper was wrinkled.

 

[Showkey]

Dehumidifiers do not function in cold temps........even the low temp models have limits around 50*.

 

[kbs2244]

but you don't get humidity in the cold
it turns to frost or snow

 

[Showkey]

^^^^^^^^Any change in temperatures and dew point you will get condensation and or moisture problems. Once you cross the 65-85% humidity level you get the wet damp smell ( aka swampy) will see mold, mildew, on organic matter like leather, cloth, paper, wood and rust on steel. That’s why it’s so difficult or nearly impossible to control humidity if the building or unit is not temperature controlled or as they say conditioned air. Ventilation is the only cure and depending on location may not be all that successful.

As for being cold and that solves the problem..........
Right now it’s 28* 78% humidity outside inside is a conditioned space it’s 68* 23% humidity many posts talk in summer basements being 65* and 70% humidity, smells wet, moldy etc........perfect for dehumidifier....because you have control of the temperature. 70% is that sweet spot for bad things to start happening. Running a dehumidifier for day or two your back to 50% humidity and the problem is gone and you emptied the bucket 3 or 4 times.