When your home was built the contractor probably was required to pretreat the soil before pouring the concrete slab. By AZ law a final grade was to be performed within a certain period, if you look in the electrical box you may find the two required stickers. One should be the original pretreat and the second is the final grade. Now that’s if they haven’t fallen off or are not legible. You can also visit the Office of Pest Management site at http://tarf.sb.state.az.us/index.php?ckset=ok – they started keeping track in 1990 I think.
Back in the day termiticides like Chlordane could last for 50 years, but in my opinion today I think it is closer to 15 years. Especially when placed under concrete without things that would break down the chemical. The outside of the home or that final grade is another completely different story. If nothing messes it up it might last 7 years but that doesn’t happen very often. Water, rodents, sun and the heat, people installing pipes or wires often disrupt that barrier. It is my opinion that you shouldn’t plant anything under the eaves of the roof line, roots and water may affect the home and you don’t need anything else to worry about.
So keep checking your foundation, clear away rocks or soil from the stucco area – you need to be able to see that foundation. Don’t stack firewood against the home or for that matter any other debris. As always if you need an inspection give ProBest Pest Management a call at 480-831-9328 or 623-414-0176.