Cross section of pressure treated fence post after 6 years. Subterranean termite damage is extensive.
At Thrasher Termite & Pest Control, we pull out a lot of subterranean termite damage from homes, but frankly we were surprised by the amount of subterranean termite damage found in this six-year-old pressure treated fence post. After all, isn’t pressure treated wood supposed to be resistant to termites?
How long does pressure treated wood last?
Clearly not as long as you think!
Pressure-treated lumber is wood that has been immersed in a liquid preservative and placed in a pressure chamber. Pressure forces the chemical into the wood fibers. Pressure treated wood is classified by expected product performance for a particular use–the Use Category System (UCS). Wood recommended for fence posts is rated UC4A or UC4B. This rating us usually found on a little tag stapled to the end of the piece of lumber.
The installer of this fence used UC4A lumber–the recommended choice for treated wood used in contact with the ground. So then, how did subterranean termites do so much damage in such a relatively short time?
1. The piece of lumber may have been mislabeled.
2. The producer of this piece of lumber may have done a shoddy job of pressure treatment.
3. Six-years might be the life-span of UC4A pressure treated wood exposed to subterranean termites.
Don’t rely on pressure treatment to protect your fence from termites. The best way to ensure your fence is not destroyed by subterranean termites is to eliminate wood to soil contact. Subterranean termite colonies live in the ground. Worker termites cannot last long outside of their soil or wood tunnels. Keep wood away from the soil to thwart subterranean termites. Attach fence posts to concrete piers set above the soil surface. Keep soil, leaves, and mulch away from fence posts and the base of the fence.
This advice will keep subterranean termites away from your house: keep soil, leaves, and mulch below the concrete footer of your house, and definitely away from any wood siding. Do not attach wood fences or gates to your house. Every three years, order a complete termite inspection of your home from a licensed pest control company such as Thrasher Termite & Pest Control.