Pressure treatment is a process that forces wood preservatives or fire-retardants into the wood. These
processes are considered the best and most effective method to extend and preserve timber life. Preservatives protect the wood from attack by wood ingesting insects; like termites, and wood rot caused by fungal decay. Fire-retardant treatments help the wood to quickly char when exposed to flame, reducing the smoke and flame that occurs in a fire.
This short video shows how lumber is pressure treated for all treated wood needs from decking to marine pilings.
For some western wood species, incising is a common process where the wood is resistant to preservative penetration, but the preservative will penetrate along the grain. These wood species are prepared by creating small incisions into the wood prior to the pressure treating process. It is common practice to incise all sawed Douglas fir three inches or more in thickness before treatment. Check out this two minute animated video on the treating wood process for western species.
In a recent article, "What is pressure-treated lumber, and how does it forestall decay?" in Chemical and Engineering News' March 7, 2022 issue, writer Craig Bettenhausen explains, "Old wood-preservation chemistries have fallen out of favor, and new ones are in the works. But most wood used outdoors by consumers today fights off fungi and insects with these mixtures. Copper is a broad-acting fungicide and insecticide, azoles kill fungi, imidacloprid kills insects, and dichlorooctylisothiazolinone (DCOI) kills fungi and bacteria.
In 2018, Viance introduced UltraPoleNXT with DCOI to the infrastructure market for a more environmentally advanced wood preservative for utility poles. DCOI is the active ingredient and a preservative of choice to replace penta (pentachlorophenol) that ceased production in December 2021.
Learn more on the preservatives used today for pressure treating lumber.