Practical Engineering: Buckling Under Pressure

Most framers install thousands of wooden studs and built-up posts every year without ever questioning their ability to carry vertical loads. Conventional job-site wisdom says that, in most cases, 2x4s are plenty strong and that 2x6s, used primarily for the extra room they give for insulation, are overkill — even on 24-inch centers. For the most part, this conventional wisdom is right. Studs and columns rarely fail from compression — that is, being crushed under load. But there are situations where extra wall height or greater than normal loading might cause a stud or a built-up post to fail by buckling, or suddenly bowing out to one side. In theory, a slender column made from elastic material such as wood