the only place those carpenter ant's will build a colony is where something never got flashed or something was incorrectly built
as in two joists doubled up somewhere that never gets a chance to dry out... making the wood perfect for them to chew.
the wet spot..........
you find that and your problem is easy to solve...otherwise they keep coming back.
Yesterday I moved a tarp to find an ant colony with thousands of eggs. In less than ten minutes they ants had packed their belongings and moved every single egg off to somewhere else.
That's amazing when you think about it. Their social order and instinct must be very strong and very simple.
Get some boric acid ...... it's a white powder ....... I usually get it at the Dollar Stores down here .......... get a couple of old film cannisters and poke a few holes in the tops big enough for the ants to get in. Stuff the cannister 1/2 way with cotton balls. Take a stir and a small disposable cup (bathroom mouthwash size is fine) Mix equal parts of sugar and the Boric acid with with a few drops of warm water until you get a thick syrup. Fill the cannister and smear alittle on the outside of the cannister to the holes. Then put the cannister in the area you find the ants. Hopefully behind something where kids and animals don't go. THen let the ants swarm over the cannister and feed to their hearts content. THey will take the stuff back to the nest and in a week or so the whole nest will be dead. This really works.
just keep it away from animals and kids. The good thing is that you don't have to spray ........ it also works better than the commerical ant traps
Also ....... keep your eyes out for termites ......... an exterminator told me that carpenter ants love to eat termites .........