How do I prevent home-center wood from warping?
It seems like every pine board I buy from the home center soon warps and becomes almost unusable. How can I stop this?
—Gary Olsen, Duluth, Minn.
The mills that process dimensional lumber (pine, fir, etc.) kiln-dry softwoods to higher moisture content than for hardwoods. In other words, softwoods leave the mill "wetter" than hardwoods. Those softwood boards then ship to the home center in tight bundles that prevent both additional drying and the warping that can result from it. Freed from those bundles in the drier climate of your shop, the boards typically begin to bend and twist. So, you can't really stop warpage, Gary, but careful stock selection—both before you buy and after you get it home—can minimize
Begin by choosing boards with as much quartersawn or riftsawn grain [Photos A and B] as possible; they will be more stable. Minimize flatsawn grain and accept that unstable portion of the board as waste; avoid working with 2×4s [Photo C] when possible. Also, thicker and wider boards usually hold a higher percentage of usable stock. For example, about 2⁄3 of the grain in the 2×12 shown in Photo B is riftsawn. This typically happens with wide 2-by stock to meet building strength standards for floor joists, rafters, and stairs.
Once you bring the wood home, break it down right away to minimize any movement. (It's easier to remove warp, if necessary later on, from smaller boards than longer, wider ones.) If you're building a specific project and know the parts dimensions, rough-cut those parts about 1⁄2 " to 1" longer and wider. This will leave you some wiggle room later. For now, do not alter the thickness. If you don't have specific part sizes in mind, cut away the waste areas to create manageable-size workpieces for later, such as the board shown below. With that done, let the boards acclimate for at least a week before final dimensioning.