Hi thrifty,

ABSOLUTELY, you need to take care of the ants first. There is TONS of information on the WEB about Carpenter Ants. I searched for +"carpenter ants" and +kill (Both keywords/phrases together in a WEB Search Engine like AltaVista.com), and got over 900 'hits' on the search. (In fact, if you cut and past the keys into the Search Box, you'll get them too.)

You need to be sure that what you have is Carpenter Ants and not Termites. So, learn what you can about one and/or the other to be sure. From there, you can start the cleanup process. The KEY to this process is to dramatically reduce, or better yet ELIMINATE, any 1 or all of the 'conditions' in which the buggers thrive. In other words, if you 'alter' their environment juuuuuust enough, they will die or go away. HOWEVER, if you don't alter the conditions enough, they may just go deeper or move to a nearby location. You need to look at the BIGGER picture so that if they move on, they move to your NEIGHBORS house; NOT just 'around the corner of your house'. See what I mean?

Go here: AltaVista.com, then click the DO-it-yourself pest control link, then click on the link for Carpenter Ants, and start reading. Again, be SURE they're your problem.

My best to ya and hope this helps.

Jay J -Moderator

PS: Regarding your porch, you need to give more details on what's going on now and what you want to do. DO realize - I/we can't see it from here. Please give a respectable amount of info ...

Thanks for Ant info, as for the porch. The sill is a 6 x 6 and is on a cement foundation. The finished porch is not supporting the main structure of the house.It is situated over about a 3 foot crawlspace. The sill definitely needs to go and possibly some floor joists.

It shouldn't matter which you do first; carpenter ants don't actually eat wood, they just burrow or excavate into wood that's already rotten or unsound.
Like Jay J said, you don't want them to just move over a bit and then come back, which is why it's important to locate the nest (or nests--carpenter ants often have a parent and satellite nests).
I actually have a post on the topic here if you're interested: http://antinvasion.net/get-rid-of-carpenter-ants-in-house/