Preparing Your Belongings for Long-Term Storage

The methods used in long-term storage differ based on how long the items will be stored, the location they’re put in and, most importantly, how sensitive the items are to things like humidity, temperature and other variables. For the purpose of this guide, long-term storage includes any period over 90 days.

How to Prepare and What to Avoid

All items should be washed and completely dry before packing, because dirt and moisture encourages mold growth and attract pests. Large appliances, such as fridges, dishwashers or ovens, should be cleaned inside and out, dried with a cloth to remove obvious moisture and then left to air dry with their doors ajar.

Use High-Quality Boxes — Avoid Plastic Bags

If you’ve ever seen the back rooms at a museum, you would’ve seen a lot of boxes and not so many plastic bags. Museum employees tend to know a thing or two about long-term storage, and they go to great lengths to make sure their collections are protected.

The average person doesn’t need to be quite as picky with the storage materials they use — a regular moving box is fine, preferably new so you’re not bringing in contaminants.

However, when dealing with fabrics, such as clothes, curtains and bedding, plastic vacuum-sealed bags are recommended because they’re generally safer than regular plastic bags for long-term storage. It’s still important to get high-quality bags that won’t leak or burst and make sure all of the air is sucked out before storage.

Use Shelves or Pallets When Possible

This is a simple one, but you may be surprised at how much potential damage can be avoided by raising stored items instead of putting them on the floor. Use the shelves if your unit has them, or place pallets on the floor to create a buffer.

This buffer zone not only helps prevent water damage in case of minor flooding, it also allows air to circulate much easier. Pallets are cheap, and if you ask nicely at home improvement and gardening stores, they’ll often give them away. This could backfire, however, because the used pallets may not be clean and may be contaminated or rotting. Choose clean, dry pallets, preferably ones that were recently unpacked rather than those that have been sitting outside for a long time.

Wrapping and Packing

Whether they’re going away for a few months or a decade, the wrapping and packing of items remains mostly the same. Fragile goods should be wrapped in paper and packed fairly tightly in boxes to minimize damage from vibration.

• Books and Paper Documents: Books should be kept flat and stored in boxes. Archival-quality boxes and book cartons are available for important collections.
• Glassware and Fragile Items: Wine glasses and other small items should be wrapped in paper or foam. Look for foam sleeves — otherwise known as glass socks — which add cushioning for fragile items. Fill empty space in boxes with padding, and clearly mark it as fragile.
• Clothing and Fabrics: Use high-quality vacuum bags with tight seals. Special cartons are also available that allow clothing to hang, as they would in a wardrobe, which minimizes stress on fabrics. Naphthalene (mothballs) or cedar balls can also be used around fabrics that aren’t in vacuum-sealed bags to repel insects, mildew, and odors.
• Furniture: Remove cushions and store them in boxes with other fabrics. Wrap all mattresses and large furniture in moving blankets, including the underside, to maximize protection.
• Appliances and Electronic Components: Appliances should be clean and dry, with smaller ones wrapped in paper and larger ones wrapped in dust covers. All sensitive components should be kept in commercial packaging and stored in conditions suggested by the manufacturer.

The Main Threats to Stored Items

• Moisture and humidity
• Temperature
• Light
• Dust
• Insects and rodents

See below for more details on climate control and the ideal temperature and humidity range for some of the most commonly stored items. Rising and falling humidity causes materials to expand and contract, which may happen multiple times per day in poor storage conditions, so this should be a top priority to get under control.

Consider Climate Control

Storing your valuables and treasured heirlooms may require more control over the environment than what is possible in a regular unit. Controlling the climate isn’t simply making sure the items don’t get too hot or too cold — it’s designed to prevent or minimize the regular fluctuations in temperature, from day to night and winter to summer. Humidity is also very important and can lead to disaster if left unchecked.

Temperature

Wood, paper, film, electronics and some fabrics are particularly sensitive to temperature. This affects books, paintings, furniture, appliances and could even cause a problem for your old record collection.

A good climate-controlled storage unit should be at, or close to, the same temperature no matter the season or time of day. The exact temperature that it’s set to is not as important as maintaining it at a consistent level.

Lower temperatures are almost always better for long-term storage. The general rule is that chemical reactions take place slowly when the temperature is low. This means that an item stored in ideal conditions will last for a longer time while sustaining less damage.

Most items will benefit from being kept at a consistent temperature that is above but near freezing point; somewhere around 40°F to 50°F is good.

This type of cold storage isn’t always necessary for the average person, but it’s the ideal scenario, and this is how priceless old books and antiques are stored. You’ll need to consider the cost of climate-controlled storage based on the value of what you’re putting in it, whether it’s monetary or sentimental.

Humidity

The relative humidity (RH) of the storage environment is just as important as temperature, and it could be even more important depending on where you live and what you’re storing. Moisture is almost always bad — it’s the enemy of long-term storage, and it must be dealt with properly when storing valuable and sensitive items.

It’s important to keep the humidity low and consistent, just like the temperature. Luckily, the relative humidity in any given area tends to drop as the temperature goes down, so it’s not as difficult as it may sound to keep these two factors on point.

The ideal humidity range for the most commonly stored items — wood, paper and fabrics — is around 40% to 55%.

However, many items enjoy a higher or lower relative humidity. The rate of corrosion in iron spikes dramatically if the RH goes above 60%. Wine is usually stored at 65% to 75% RH, because dry air can crack the corks and ruin the wine, and some electronic components are stored as close to 0% RH as possible to avoid any risk of corrosion.

Using Desiccants and Humectants

If you can’t justify the expense of a climate-controlled storage unit, consider using desiccants or humectants as a very cheap alternative.

Desiccants absorb moisture from the air, which lowers the humidity. You’ll often see desiccants such as silica gel packs with new shoes, clothes, medicine and even food. This keeps food fresher for longer and prevents the fabrics in shoes and clothes from getting too moist in storage, which can cause an unpleasant smell at the very least.

Humectants do the opposite — they’re used to help retain moisture. It’s much less common to use humectants, because moisture is generally bad for storage purposes, and these substances are mostly used in consumables such as food, makeup and tobacco products.

Desiccants and humectants are produced commercially in varying sizes for different applications, but they’re all temporary solutions that need to be replaced after some time. It’s also possible to use common household goods, such as uncooked rice. However, this is far less effective and not recommended for long-term storage because it may attract pests.