Steve from Paris, Il writes
The best treatment option for this area is to just pull the boards closest to the house up and trench the dirt and then nail the boards back down. If you are unable to pull the boards up you have two other possible options. You would need to treat this as a concrete area that you will need to drill through just like a garage or driveway that might be in the way of trenching. You can try trenching all the way around the deck but you are still left with the possibility of the termites being able to come up the foundation in the untreated area under the deck. Please see the instructions for drilling holes in concrete in our How To Do A Termite Treatment guide for tips on this application.
Answer last updated on: 06/04/2013