Be aware that a board isn’t necessarily flat or straight; crooked boards are fine for many construction jobs, and there are many opportunities for a board to warp between the lumber mill and the checkout line. Before buying a board, look down its length, and be sure that the board runs straight without bowing (curving up from end to end, like an archery bow), cupping (curving along its length, so that it forms a gutter instead of a flat board), twisting, or warping. Also look out for cracks or loose knots; knots smaller than a quarter are usually tight, which means they are well-integrated with the surrounding wood and will stay put. Larger knots, especially those surrounded by a dark ring, often fall out as the wood ages—hence the term loose knot.

Savvy readers are probably wondering why the Lock-n-Latch Treasure Chest’s end pieces are cut to 5 3/4″, instead of 6″. After all, the height of the box is the same as the width of the board (nominally 8″). Subtract 1″ of thickness for each of the top and bottom boards (since they are cut from a 1″×8″ board), and it should call for a 6″ tall end piece. But as it turns out, a 1″×8″ board is actually more like a 3/4″ by 7 1/4″ board. There’s a variety of reasons for this: When the boards are initially milled, some of the lumber is eaten up by the thickness of the blade (called the kerf), so both the width and height of the boards end up about 1/16″ to 1/8″ smaller than expected. Then the boards are smoothed with a plane and kiln dried, processes that further reduce the finished dimensions. Since lumber dimensions were much more variable in the past, building techniques and codes tolerate wild variation. As mills became more precise, it became possible to deliver sturdy, high-quality lumber with less waste. Lumbermen realized that they could actually make each board a little smaller from the start with no ill effects; saving 1/8″ per board doesn’t amount to much more than a fraction of a cent, but over the course of a few million board feet of lumber the interest compounds. In the end, it’s all about the Benjamins, baby.