Why a 2×4 Isn’t

lumberBy Matt Henke, Builder

In kindergarten I was taught that 2+2=4. It was a universal truth that was guaranteed to never change. I find comfort in knowing certain things are certainties. And then there are other certainties, like death and taxes, that aren’t as comforting. That being said, a 2×4 is a different story. If you were to go to your local home improvement store you would stroll down the lumber aisle and find a stack of wood labeled 2″x4″. And any right-minded individual would deduce that this means that this lumber is 2 inches by 4 inches in dimension. But you would be wrong. The average 2×4 is actually 1 1/2 inches by 3 1/2 inches. Although some may argue otherwise, it’s not a scam. When the wood is roughly cut from the log, it is cut to 2 inches by 4 inches. But after it is planed smooth and allowed to dry, it settles at the smaller dimensions. Think of it like ordering a 1/2 pound burger. The patty is likely 1/2 pound before it’s cooked, but when it comes off the grill it’s something less than that. And yet it is still sold as a 1/2 pound burger! That’s your 2×4.

And just to make things more interesting a 2x4x8 isn’t 8 feet long (96″). It’s actually only 93″ long. That’s because this lumber, often called a “stud,” is used in constructing 8 foot walls. These walls have a 2×4 at the top and bottom, so if your take off the 3 inches for these two boards, you end up with 93″. Since 2x4s are used  every 16 or 24 inches on a wall, it’s much less time consuming if they don’t have to cut those boards down to size first, so they come already cut to 93″.

Crazy, isn’t it? And if your head isn’t spinning yet, you should know that all dimensional framing lumber is smaller than how it’s labeled…for the same reasons. But even if dimensions have changed, it’s good to know that arithmetic hasn’t. 2+2 still equals 4.