Pressure treated (PT) lumber is designed for outdoor applications. It is treated with a copper-based preservative to mitigate the chances of rot and insect damage. The application of the preservative leaves the lumber wet. When lumber is wet it expands in length and width and shouldn't be used for construction. In order for the lumber to be used, it needs to be dried slowly to prevent warping. This process can take several weeks depending on local climate and weather conditions. It is smart to order your lumber early to accommodate drying time.
Things You'll Need
3 pieces of (4 inch by 4 inch by 4 foot) lumber
Thin wood strips (4 feet in length)
Locate a flat spot that is out of the sun and not in an area where water can pool. The area needs to be large enough to accommodate the length of the boards you need to dry.
Lay the three 4 by 4 inch by 4 foot lumber pieces, evenly spaced, along the flat area. The pieces should be parallel to each other and spaced properly to accommodate the pressure-treated wood that will be laid on top of it. These pieces will keep the PT lumber off the ground.
Lay the first row of PT on top of the 4x4s, leaving 1/2 inch of space between each board.
Lay three thin wood strips on top of the PT lumber in the same locations as the 4x4s on the ground.
Lay PT lumber on top of these strips in the same manner as the first row. Repeat the process of laying the PT lumber, then spacer strips, then the PT lumber, until all the wood is stacked. This stacking process provides space for air to move though the lumber.
Cover the wood pile with the tarp, but allow openings at each end so wind can move through the wood. Secure the tarp to the ground by placing evenly spaced bricks on top.
Wait 2 weeks for the lumber to dry, then inspect it for proper moisture level.