Prepare the mattress before moving it
A mattress stored improperly will absorb moisture, develop mold, and lose its shape within weeks. Before you move it into the unit, clean the surface with a dry cloth or vacuum to remove dust and debris. If there are stains, let them dry completely — moisture trapped inside the mattress is the main cause of mold growth.
Wrap the mattress in a breathable material, not plastic. Plastic sheeting traps condensation against the fabric and creates the exact environment mold needs. Use a mattress storage bag made of heavy paper or cloth, or wrap it in old sheets and find them with tape. The goal is to keep dust and pests out while letting air circulate around the surface.
If you are storing a foam mattress, be especially careful during wrapping — foam can tear easily. Lay it flat on a clean surface, wrap it gently, and avoid dragging it across rough floors or concrete.
Key Takeaways
- Store the mattress flat on a solid base, never on its side or standing upright, because the weight will compress the foam or springs unevenly and permanently.
- Wrap it in breathable material like paper or cloth, not plastic, because plastic traps moisture and causes mold to grow inside the mattress.
- Keep the storage unit dry by using a dehumidifier or moisture absorbers, since humidity is the single biggest threat to a stored mattress.
- Do not stack anything on top of the mattress, and do not lean items against it, because pressure will create permanent dents and sag.
- Store the mattress away from windows and exterior walls where temperature swings and condensation are most likely to occur.
Position the mattress flat on a solid base
Lay the mattress flat on the floor of the storage unit, never on its side or standing upright. When a mattress stands upright or leans at an angle, the weight concentrates in one area and compresses the foam or springs permanently. A mattress stored this way will sag in that spot even after you bring it home and lay it flat again.
Place a thin layer of plywood or cardboard under the mattress to keep it off the concrete floor, which holds moisture. The barrier does not need to be thick — a half-inch of plywood is enough to create air space underneath. If the storage unit has a wooden pallet, that works too, but make sure the pallet is clean and dry before you set the mattress on it.
Do not store the mattress directly on concrete, and do not store it on a metal frame or bed base inside the unit. Metal conducts temperature changes and can rust, and the frame will leave marks on the mattress fabric.
Control moisture and temperature in the storage unit
Humidity is the biggest threat to a stored mattress. Even in a climate-controlled unit, moisture can build up if air does not circulate. Place a dehumidifier in the unit and run it continuously, or use moisture absorbers like silica gel packets or calcium chloride containers. Check them monthly and replace them when they become saturated.
Temperature swings also damage mattresses over time. Avoid units in direct sunlight or on the south-facing side of a building, where heat builds up during the day and cools rapidly at night. This cycle causes condensation to form on the mattress surface. A climate-controlled unit costs more but is worth the expense if you are storing the mattress for more than a few months.
Ventilation matters as much as temperature. If your unit has a vent, leave it open slightly to allow air to move through. If it does not, crack the door open a few inches on dry days to exchange stale air for fresh air from outside.
Protect the mattress from pests and pressure
Do not stack boxes, furniture, or other items on top of the mattress. Even light pressure will create permanent indentations in foam and compress the springs. The same rule applies to leaning items against the mattress — a chair or shelf leaning on one side will leave a dent that does not come out.
Keep the mattress away from the walls and door of the storage unit. Exterior walls and doors are where temperature swings are most extreme, and condensation is most likely to form. Store the mattress at least one foot away from any wall, and farther from the door if possible.
Pests like bed bugs, dust mites, and rodents can hide in a stored mattress. Inspect the mattress before you wrap it, and check it again when you remove it from storage. If you see signs of pests — small dark spots, a musty smell, or visible insects — do not bring it into your home. Pest damage is usually permanent and spreads quickly.
Check on the mattress periodically
Visit the storage unit every two to three months to check on the mattress. Look for signs of moisture, mold, or pest damage. If you see mold spots or smell a musty odor, open the unit door and let it air out for several hours. Wipe down the mattress with a dry cloth and increase the dehumidifier setting or replace moisture absorbers more often.
If the mattress has been in storage for more than a year, consider having it professionally cleaned before you use it again. A mattress cleaning service can remove dust, allergens, and any mold spores that may have started to grow. This is especially important if anyone in your household has allergies or asthma.
Know when to replace instead of store
An old or damaged mattress may not be worth storing. If the mattress is already sagging, has visible stains, or smells bad, storage will not improve it. A mattress that was uncomfortable to sleep on will still be uncomfortable after storage, and the storage process itself may make existing damage worse.
If you are storing a mattress you plan to use again, make sure it was in good condition when you put it away. A mattress that is ten years old or older is nearing the end of its useful life, and storage does not extend that. Most mattresses last seven to ten years with regular use, and storage does not reset that clock.
Frequently Asked Questions
Can I store a mattress standing up to save space?
No. Standing a mattress upright will permanently compress the foam or springs on the bottom edge. The mattress will sag in that spot even after you lay it flat again. Storing it flat takes up more space, but it is the only way to keep the mattress usable.
How long can a mattress stay in storage?
A mattress can stay in storage for one to two years if the unit is climate-controlled and you use a dehumidifier. Beyond two years, the risk of mold, dust mites, and permanent compression increases. If you need to store it longer, check on it every month and consider professional cleaning before you use it again.
What should I do if mold grows on the mattress?
Remove the mattress from the unit when ready and let it air dry in sunlight for several hours. Wipe the surface with a cloth dampened in white vinegar, then let it dry completely. If the mold covers a large area or the smell does not go away, the mattress is not safe to sleep on and should be replaced.
Do I need a climate-controlled unit to store a mattress?
A climate-controlled unit is better, but not always necessary. If you use a dehumidifier and check on the mattress every two to three months, a standard unit can work for storage lasting a few months. For longer storage, climate control is worth the extra cost because it prevents the temperature and humidity swings that cause mold and mildew.
Can I store a mattress in a basement or garage instead of a storage unit?
A basement or garage works if it stays dry and you can control humidity. Basements are often damp, and garages have temperature swings that can damage a mattress. If you choose either option, use a dehumidifier, keep the mattress off the floor, and wrap it in breathable material. Check on it monthly for signs of moisture or pests.