How to get rid of carpenter ants?

I have a house that's over 100 years old and just found a pretty serious carpenter ant infestation that seems to be centered around one window. (I didn't realize that I have a water issue and have a lot of rotten wood around that window.) Which do I do first, replace the damaged wood or call the exterminator? Will replacing the rotten/infested wood get rid of the ants (making the exterminator unnecessary?) Is there a pesticide that I can use instead of using an exterminator?