Is pressure treated lumber termite resistant?

Answer 1

Lumber used to be pressure treated with arsenic - a lethal poison - specifically chromated copper arsenate - which turned the lumber slightly green- but legislation was passed several years ago ( 2003 ) stopping the use of arscenic and going to less toxic substances. Another copper solution called ACQ is used. The copper makes the wood more rot resistant and is toxic to some insect life. Termites would tend to favor untreated wood. While the bottom sill of balloon frame structures may be pressure treated, the framing above the bottom sill is most often not treated. It is too expensive to build structures entirely from pressure treated lumber. The best defense against termites is to keep the wooden parts of the structure well off the soil with stone or concrete foundations and keep those foundation lines clear of flower beds mulched in wood chips so as not to give termite colonies easy access.