How do you treat termite invasions short a company?
If you need to ask this request for information you can't. Bite the bullet and pay a pro, or bite a Howitzer shell and pay packet for reconstruction!
While its foolish to DIY termite control because termites are not your average run of the mill pest. If you do it wrong it could cost you thousands in mess up.
But if you really want to have a step, then one of the best treatments is Termidor. This have a delayed effect of killing the termite which allows it to be poisoned and consequently have adequate time to return to the nest and then infect the rest of the colony.
See association below.
Answers: You can spray using a commercial ant killer, but you will enjoy to get where on earth the termites are and this isn't always comfortable. Typically, termites will maintain a route to the ground. If the infestation is beneath your house, porch or deck look for mud tunnels between the ground and the wood source. This is where the infestation is. Spray heavily.
Another source is damp wood. Termites will attack wet wood first, if available.
Good luck.