Start Seeing 2x4s
They are ALL around us but, unless you spend a lot of time on construction sites or in lumberyards, you’ll hardly ever notice the 2x4s in your life.
I knew they were there, lurking in nearly every wall, but it wasn’t until I went down to Biloxi, Mississippi to work on Hurricane Katrina reconstruction in 2007 that I really got to experience their presence all around me. Most of the buildings in Biloxi had been flooded in the storm and volunteers (myself included) had subsequently gutted them to their structural studs in an attempt to quell the mold which blossomed on every surface. Any building which wasn’t exposing its existing mold-deterring primed 2×4 framework to the world was likely under construction like this one in the photo above. Suddenly there were 2x4s everywhere I looked.
This wasn’t unusual. 90 percent of new homes built in the United States use dimensional wooden framing. According to Eric Corey Freed, a 2000 square foot home uses enough 2x4s to decimate an acre of forest (44 individual trees)1.
A Brief History … or why a 2×4 isn’t really 2″ by 4″
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, more often than not 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 The American Lumber Standards, adopted in 1924 created the standard of 1 1/2 inch and we use the same standards today.3
*This short history (and the above image) came from a fun historical document I came across recently on the Forest Products Laboratory website: A History of Yard Lumber Size Standards, published by the FPL in 1964. (The authors were a wood technologist, one 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.) It has a lengthy and in depth history of the standardization of dimensional lumber which I have summarized. See the real deal for more information.
What could go wrong?
Well, a stick framed building is inherently little more than an aggregation of toothpicks. It works alright when supporting a balanced vertical load but doesn’t hold up so well if anything in that equation changes. This collapsed house near Lake Delton shows what happens if the foundations of a lake front property wash away when a dam washes out.
Hey, look … 2x4s!
Wood framing construction has many problems. Again, courtesy of Mr. Freed4:
- Wood burns (in case you hadn’t heard) and it burns even better when its kiln dried and then arranged into the chimney shape that is typical of balloon framing.
- It also has a tendency to get moldy, as I learned in Biloxi. Even if you home isn’t flooded to 9 feet by the displaced Gulf of Mexico, small amounts of leaked water or even high humidity can create a haven for mold inside the walls.
- Wooden framing makes a lovely snack/house for insects like mice and other things which are cute in a hamster ball and nasty in a wall cavity (like mice colonies).
- And if not watched properly it will just rot away (a pesky fact of life with biodegradable substances) due to the same moister conditions which will first turn it into a mold incubator.
All of that is leaving aside the problems with the individual 2x4s themselves. All milled lumber is subject to warping. Like the Eskimos have many words for snow (although that might be a myth), builders have many terms for warping. Boards can cup, bow, crown, crook, twist, shake, check, split or wane. They can also be cut with diving or diagonal grain which creates weakness within the structure.
The lumber industry would have us believe that stick framed building is a time tested technique that we can rely on through the ages but in fact 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.
A 2001 report by the Kentucky-Tennessee Society of American Foresters attributes the declining quality of the local forest timber to “management over decades whereby high-quality trees were harvested from the forest and low-quality trees were left as the growing stock.”5 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.
That said, the practice of building with 2x4s and dimensional lumber in general isn’t going anywhere anytime soon. Still I think that designers are sometimes too ready to use conventional materials unquestioningly. What our buildings are made of may ultimately be as important as the design of the spaces the building materials enclose. As designers, we should consider the use of dimensional lumber carefully.