We have a relatively new house (built in 2002) with a cold storage room under the poured concrete porch. There is a door with full weatherstripping leading to it.
We'd really like to close it off (it has two vents to the outside) and turn it into a storage room (unheated), but not open to the outside to help control humidity levels. It's a relatively dry room (no pooling of water or anything).
What's the best way to close off the two vents that go outside? They are about 6 inches in diameter and about 8 inches deep (from memory, it may be more). Or should they not be closed off?