This ubiquitous building material lurks behind nearly every residential wall but is hardly ever seen. We may not see it, but it is busy holding the roof up over our heads. Today we meditate a little on this most common of building materials: the humble 2×4.
First, an old joke:
“Fellow comes into a lumberyard.”
Says to the guy, “I need some four-by-twos.”
“You mean two-by-fours?”
“Just a minute. I’ll find out” He walks out to the parking lot, where his buddies are waiting in the car. They roll down the car window. He confers with them a while and comes back across the parking lot and says to the lumberyard guy, “Yes. I mean two-by-fours.
Lumberyard guy says, “How long do you want them?”
“Just a minute,” fellow says, “I’ll find out.” He goes across the parking lot and confers with the people in the car and comes back across the parking lot to the lumberyard and says to the guy, “A long time. We’re building a house.”
Annie Dillard, An American Childhood
A 2X4 IS’T REALLY 2″ X 4″ ANYMORE
For a history of wood lets turn to a historical (1964) document written by the experts, in this case this document published by the USDA Forest Products Laboratory. A History of Yard Lumber Size Standards, by wood technologist, L.W. Smith, and an engineer by the name of L.W. Wood, who I’m betting got a lot of jokes about his name and job. Read it in full for the whole scoop. But in brief:
Until the mid 1800s, the lumber for buildings was generally produced by local saw mills to the specifications of the individual builder (or to the whim of the mill’s equipment and employees). Builders were used to working with what their local mill had to offer and there was no standardization between mills.
“Dimension was fitted into place by the carpenter, […] with his hatchet.”
As time went on, and forests resources were depleted, the milling operation took place further and further from the building site. Eventually, a rough standard had to be developed. By 1900, 2 inches was “the most common thickness for joists, rafters, studs, and the like, and 1 inch for boards.” Eventually sawmills began to run rough lumber through a small “edger or ripsaw” to smooth the edges with the side effect that the new “saw sized” pieces were “usually 1/4-inch scant of the nominal width (2).” To put a halt to this continual whittling down of lumber sizes, the American Lumber Standards, adopted in 1924 created the standard of 1 1/2 inch and we still use the same standard today.
WHAT’S SO GREAT ABOUT THE 2×4 / WHY THEY ARE SO COMMON
Dimensional lumber is cheap easy and familiar to work crews of every degree of experience. Americans have always relied on the timber industry to supply us with construction materials. Per Architectural Record’s 2010 article, Lumber by the Numbers, the US holds 5 percent of the world’s timber stock and we use it. “Over 90% of American homes are built with wood.” The timber industry has a strong vested interest in our continuing to make this material a mainstay of our construction habits.
AND THEN THE DOWNSIDE …
Yep. As with any over processed mass produced product that makes up the building block of our modern life … these little strips of wood have a few built in hitches. To whit: they’re not very sustainable. It takes a lot of energy to cut down, mill, process, kiln dry and transport all those millions of board feet.
Plus, each individual 2×4 has the potential for flaws. Trying to turn an organic organism (a tree) into a fixed, interchangeable unit (a board) is not without its problems and when selecting 2x material for a project, you have to beware of many potential flaws (nearly all created by misalignments between the wood’s natural grain and the way it was cut.) Unlike finish grade wood, which is cut from specific areas of a round log to get particular grain patterns, dimensional lumber is sliced out of pretty small-diameter trees, any way it can be. The result:
NOT YOUR GRANDFATHER’S 2×4
The lumber industry would have us believe that stick framed building is a time tested technique and that new buildings built with todays dimensional lumber will last the way our historic buildings have. But in reality, their statistics on the strength and longevity of framed buildings don’t really apply to the kind of building we do today. More things have changed since the 1920s than the dimensions of the lumber. The 2×4 material that was being milled a hundred years ago was sawn from a dense grained old growth timber resource that doesn’t exist anymore. A combination of clear cutting and of selecting and harvesting the best quality wood from standing forests. Looking inside the wall of a century old building will not only show you lumber that measures 2″ by 4″ but wood that is denser and stronger than the 2×4 material available from lumber yards today.
IN THE END(GRAIN)
So what’s the upshot? For the moment, we are going to keep designing and building with dimensional lumber in many situations. We can, however, try to minimize the need for new construction, specify new milled lumber with care, and keep our eyes open for new alternatives coming on the market to provide an alternative.
*NB: parts of this post were ruthlessly cribbed from a piece I wrote in 2011. Read that earlier post here.