Pressure-treated wood is designed for use on projects exposed to the elements. Originally, pressure treatment included the use of arsenic. Such formula was proven effective in protecting the wood. However, it has risks of toxicity for both humans and pets. Because of this, modern wood manufacturers started to experiment with other formulas and came up with Alkaline Copper Quaternary or ACQ-treated wood. Although toxicity is not a problem with this formula, it presents its own risks. Because of the high levels of copper in the material, it becomes more conductive, causing possible material corrosions when it reacts with wood screws and nails. To deal with this issue, manufacturers offer specially-treated screws engineered for use with wood treated with ACQ.
Buying Pressure-Treated Wood
When you purchase pressure treated lumber in home depots, you will notice that wood arrives there wet. This is due to the treatment process. Manufacturers want to their wood to the stores as quickly as possible in this condition so it sells before it starts to dry unevenly. When wet, the wood’s fibers soak up as much liquid as possible. When the wood starts to dry, it tends to significantly shrink across the fibers with little shrinkage occurring along the boards’ length.
Therefore, when buying pressure-treated wood, there is no time to wait for it to dry and see which boards warp and twist and which doesn’t. To judge which boards to purchase, you must inspect the boards’ long edges to spot any blemishes or weak spots. Also, you can check the wood’s end grains. Pick wood with grain lines across the board end’s narrowest span.
Working with Pressure Treated Wood
If you are constructing an outdoor project like a deck, you need to use pressure-treated lumber. This lumber must be installed with gaps between the wood. Such gaps will appear between the boards as the wood starts to undergo shrinking. Moreover, to resist cupping, boards with end grain must be positioned in the shape of an arc to ensure the center of the grain is pointing away from the adjoining part. A deck screw or more must be placed through the board’s center to help in reducing the bowing when the board dries.
Because pressure treated wood contains chemicals that can be harmful to humans and pets, it is important to consider some extra precautions. This lumber must be used on outdoor projects and must not be burned.