Pressure treated wood helps a pole barn last. Untreated wood is open to damage from ground moisture and termites. So builders can pressure treat the lumber for pole barns to protect it from rot, fungi and termites that could shorten the building’s life.
Where Pressure Treated Wood Goes in a Pole Barn
Builders use pressure treated wood mostly for skirtboards, building posts and laminated columns. They can also use it for plywood sheathing, girts and other framing members if there is a threat of termites or a concern about fire.
Common Wood Preservatives
The most common chemical preservatives are chromate copper arsenate (CCA), alkaline copper quaternary (ACQ) and copper azole. Several other treatments see less use.
How the Pressure Treating Process Works
Pressure treatment is the most effective way to chemically treat wood. First, workers usually incise the wood to create divots on the surface. That way, the chemicals can penetrate deep into the wood.
Next, they load the incised lumber onto a flat car and push it into a long tube called a retort. Then they force a water solution with preservative chemicals into the wood under pressure until it saturates the wood.
After that, they remove the treated wood from the retort and let it drip dry. Once it dries, they test the wood to be sure the preservatives went deep enough to protect it.
Preventing Twisting in Pressure Treated Wood
As they grow, trees develop a spiral twist in their grain. The pressure treating process adds moisture and preservatives, and then the water leaves as the wood dries. This loss of moisture speeds up the twisting.
However, you can largely avoid twisting if you use the wood as soon as possible after delivery. Bracing the lumber in a structure also reduces twisting. So plan to put treated lumber to use soon after it arrives.
