An attic can feel like an oven during the summer and an ice box when it’s freezing outside. Here are 10 things to consider before piling your belongings up there:

1. Heat can damage memorabilia like photographs, collectibles like baseball cards and keepsakes like scrapbooks—or anything else made from paper. Find a cooler place in your house to store cherished papers so they won’t yellow, fade and decay.

2. Even if a little bit of water gets into the attic, it can rot wood and leather and create mold and mildew. Unless you’re sure the space is sealed up tight, keep those products out of the attic.

3. Pack your storage items into sturdy, plastic boxes with snug-fitting lids, not in cardboard. The plastic bins will protect them better. Other good options: ceramic, glass, metal and other containers that are non-biodegradable.

4. Heat also can melt cheap or old plastics, even in a well-ventilated attic. The attic is not a good place to store paint or varnish.

5. Cover everything you store in the attic, either by enclosing it in a box or wrapping it in a tarp. This goes for bulky objects, too, like artificial Christmas trees, which you should protect from the elements.

6. Attics attract bugs. The occasional critter—a mouse or even a bird, for example—might even find its way into the attic through a tiny opening in the roof. They’ll claw, chew and peck at your possessions until they’re shredded. That’s another reason to keep them enclosed or at least covered up.

7. Consider the damage a cold attic can cause. Hot-and-cold cycles can cause products to delaminate, discolor, harden and become brittle.

8. It’s human nature to fill the space we have. So beware of filling your attic with junk that you don’t really need to save. Sift through your storage items and decide what you really want to keep and what you can donate or throw away. Don’t just shove it out of sight because you’re attic is cleaned up and ready for storing things.

9. Watch out for exposed nails. A sharp edge can puncture your items if it brushes against then or if you pile them on top of it.

10. If your attic doesn’t have its own floor—and it’s likely that’s the case; the ceiling of the house often creates the floor of an attic—don’t place anything heavy directly on the drywall. It’s unsupported and will not hold much weight. Even a slightly heavy box can push right through the ceiling and into the house—which will leave you with a big hole in the ceiling to repair.