OK, a lot of misconceptions going on here....
Carpenter ants can and will live in dry wood or dry spaces. They PREFER moist or wet wood, only because it is easier for them to excavate, but they are extremely adaptable. They do not eat the wood to digest it, unlike termites, ants just make their house in it. We find them nesting in interior hollow doors, underneath attic insulation, etc. As long as they have a source of moisture...leaking pipe, condensation, whatever, they are good to go. They do need moisture to survive, but they can find it in a house rather easily.
Carpenter ants do not usually nest in the ground. Generally they are found in a tree, stump, wood pile, etc. They will travel 100 yards to nest in your house. We find them crossing utility wires to the house and also tree branches that are touching your roof all the time.
Most people see an ant in their house, and they say "that's not a carpenter ant, it's too small." Carpenter ant colonies have about 5 different sized ants. The queen is the biggest, about an inch..then reproductives, which are the winged ones and a little smaller...their workers are actually quite smaller and most people mistake them for not being a carpenter ant, but they are.
If you have ants in your house, it is not a sure sign of a moisture problem. Yes, like I said, they prefer wet areas...thresholds, where decks meet the house, improperly flashed areas like chimneys, etc. They WILL nest in dry areas also.