What they said. Common sense dictates if you want anything half way decent to last...keep it out of the moldy, musty crawlspace. I have some kits that are easily 30 years old, and although the plans have somewhat yellowed, the contents are perfectly fine. I wrap the box in pallet wrap before I put it in a closet. The same closet with mothballed coats and linens, shoes, etc.

As long as you don't live in the Congo in a thatched roof home, you should be in good shape