Why is a 2×4 smaller?

“Dimensional” lumber is the general name for framing lumber. Now, most timber is milled and planed to give it a little more of a finished look, and a little more of a consistent size and profile. Because of this extra milling, a 2×4 no longer measures a full 2 inches by four inches.Click to see full answer. Herein, are 2×4 getting smaller?Through the drying process, the boards naturally shrink, as moisture leaves the beams. The real shrinkage, however, comes when the “rough-sawn material” is sent to a planer, which rubs the surface of the wood down into the smooth shapes you can purchase at a hardware store.Additionally, why is a 2×4 only 1.5×3 5? The 2×4 refers to the rough-cut green wood: it shrinks during drying, then the dried wood is planed smooth, so the finished lumber is supposed to end up at 1.5″x3. 5″. While it doesn’t really shrink that much, the mills get more usable finished 2×4’s from a given tree if they cut them slightly smaller to begin with. Also to know is, when did 2×4 become smaller? Size standards, maximum moisture content, and nomenclature were agreed upon only as recently as 1964. The nominal 2×4 thus became the actual 1½ x 3½, imperceptibly, a fraction of an inch at a time. It was a 34 percent reduction in actual volume; as those in the trade would say, it’s “selling air.”Why is dimensional lumber smaller?Lumber’s nominal dimensions are larger than the actual standard dimensions of finished lumber. Historically, the nominal dimensions were the size of the green (not dried), rough (unfinished) boards that eventually became smaller finished lumber through drying and planing (to smooth the wood).