To prevent damp and mould in storage, make sure everything is completely dry before it goes in, keep items off the floor on pallets or shelving, use breathable covers instead of plastic sheeting, leave gaps for air to move, and put moisture absorbers in the unit. Then visit now and then to check. Most mould problems come from moisture that went in with the belongings or got trapped around them.
Why damp happens in storage
Mould needs moisture and still air. A sealed unit or container full of tightly packed belongings can give it both. Damp usually comes from one of these sources:
- Items that were not fully dry when packed, such as a freshly washed sofa cover, a fridge that was not defrosted or garden furniture brought in after rain.
- Condensation, especially in metal shipping containers where temperature changes between day and night can cause moisture to form on the inside walls.
- Moisture rising from a concrete floor into cardboard boxes and furniture feet.
- Leaks or poor seals, which are more likely with older outdoor units.
Indoor units in a building are generally more stable than outdoor containers. If you are still choosing, our guide to container vs indoor storage covers the trade-offs.
Dry everything before it goes in
This is the single most useful step. Before moving day:
- Defrost and dry fridges and freezers fully, then leave the doors slightly open in storage.
- Drain washing machines and dishwashers and let them dry out.
- Make sure clothes, bedding and curtains are clean and completely dry.
- Wipe down garden furniture, bikes and tools and let them dry indoors.
- Avoid packing on a wet day if you can, or towel items down before loading.
Get things off the floor
Put wooden pallets or plastic pallets down first, then place boxes and furniture on top. This stops moisture wicking up from the floor and lets air move underneath. Freestanding shelving does the same job for boxes. At the very least, avoid putting cardboard boxes, mattresses or upholstered furniture straight onto a concrete floor.
Use the right covers and containers
Plastic sheeting and cling wrap feel protective, but they can trap moisture against the item. Breathable covers are a better choice for most things.
- Furniture: cotton dust sheets or moving blankets, not plastic wrap. See our guide to protecting wooden furniture in storage.
- Mattresses: a breathable mattress bag, stored flat or on its side off the floor.
- Clothes and linen: clean, dry and packed in boxes or breathable garment bags. Vacuum bags are fine for short periods if items are bone dry.
- Paperwork and photos: sealed plastic crates with a lid, which keep damp out better than cardboard.
Our guide to the best boxes and packing materials compares cardboard and plastic in more detail.
Help the air move and absorb moisture
Leave small gaps between furniture and the walls, and between stacks of boxes. A central walkway helps too. Avoid packing the unit so tight that nothing can breathe.
Moisture absorbers, the tubs filled with crystals that collect water, are cheap and widely available. Put a few around the unit, more in a container, and replace them when they fill up. Some people also tuck silica gel sachets into boxes of electronics or documents.
If you are using a container, ask the provider about ventilation. Some containers have vents built in, and a well-maintained container with good seals makes a big difference.
Check on it regularly
If you are storing for more than a few months, visit every so often. Open the door, let some air in, look for any musty smell, check the absorbers and look at the floor and walls for signs of water. Catching a problem early is far easier than dealing with a mouldy sofa later. Keeping an inventory of your boxes also helps you spot what needs checking.
Want a dry, well-kept unit near you? Tell us what you need and every suitable store in your area can send you a price, whether you prefer indoor storage or a container.
