While climate controlled self-storage is a great way to avoid problems with humidity, you may not be able to get a unit that has this feature. This is either due to availability, or the unit is out of your price range. That said, it's still possible to keep the items in the unit safe from being damaged by moisture. Here are a few tips you should follow.
Allow For Air Circulation
Not having any air circulation is a problem that can lead to moisture collecting in your storage unit. While the storage unit does not let much air out or into the unit since it is closed most of the time, there are still some things you can do.
Start by spacing items out in the storage unit, so that the air in the unit can move freely rather than be trapped. You should also reduce clutter whenever possible. When things are loosely piled on top of each other, they can restrict airflow and cause moisture to form.
Avoid Storing Items In Bags
You may be tempted to store some items in big plastic bags, but that can cause more harm than good to the items inside. The bag can trap the moisture inside it, since it has no real way to get out. When you add in the issues with humidity with an outdoor storage unit, you could have mildew problems with whatever items are stored in plastic bags.
Store Furniture Items Upright When Possible
When storing large pieces of furniture, you'll want to make sure that they are upright in the position they were always intended to be in when possible. For instance, if you have a couch, it should be sitting normally on the storage unit floor as opposed to upright on its side. Tables should be stored with table legs touching the floor, as opposed to being stored sideways.
This is because the natural upright position will prevent moisture from getting trapped under a surface, causing moisture damage. That sideways couch could end up being damaged along the side that was touching the ground where moisture was trapped. The sideways table could have similar damage on the edge that was resting on the ground. If the items are stored upright, potential moisture damage will be caused in places where you won't see them after they are taken out of storage.
Check with a storage unit company like Two Guys Moving for more tips on reducing moisture damage.