Wood framing is the majority of the structure of your home. While casually referred to as 2x4s, the wood used to construct walls, floors, and ceilings comes in many different sizes and lengths milled from several species of softwood conifer trees grown throughout the southeast and northwest.
Although the lumber industry works diligently to maintain quality, wood remains a natural product with individual character, irregularities, and a sponge-like ability to absorb water in humid conditions and expel that water in dry conditions. Like the sponge on your kitchen sink, the drying process can produce some pretty strange shapes. In wood, these irregular shapes are referred to as warping.
Anyone who’s bought 2x4s for a home project knows, the lumber aisles at your local home center will provide examples of the ways wood framing pieces can warp (see diagrams above). These diagrams are extreme examples for illustrative purposes, but it is imperative to check all lumber bought at the home center for straightness and relative dryness before purchasing. Looking down the length of the board with one eye closed (‘sighting’) or laying pieces on the level concrete floor are good ways to examine for signs of warping - but remember to check more than one side on each board.
Most warping occurs as a result of exposure to water that occurs in transit or storage, after the wood has left the mill but before it is installed. Warped wood can be a significant impediment to accomplishing a high quality construction project and an investment of time on-site to examine and cull out unacceptable pieces.
Lumber yards that cater to professional contractors as well as homeowners tend to have more reliable quality, but their prices are often considerably higher because they deal in a higher grade of wood than the home center.
If you are a homeowner with a DIY project or a professional who needs to pick up only a handful of wood, the home center can be a convenient and affordable source. The tradeoff for that convenience is the extra time spent sorting through their floor stock for straight pieces. For big orders the lumber yard remains the pro’s choice for less wasted time and material.