Although housing performance codes based on standard test methods are a modern development, it is known that performance requirements in codes were in effect several thousand years ago. Standard performance tests on the structural elements of houses include vertical compression and racking on walls, transverse bending and concentrated load on walls, floors, or roofs, and sandbag impact on walls and roofs. Performance requirements related to these tests have been developed. At the same time codes without these performance test provisions have included "alternative methods" clauses that are essentially performance requirements. Most codes are thus doing a good job of protecting public health and safety and at the same time permitting progress in the building arts.

Stress grading of lumber and working stresses for its use in structural design are well known. Most building codes give working stresses for wood. In the development of stress grading, principal emphasis was given to the larger timbers. More recently, increasing attention has been paid to the engineering design of light-frame structures and the strength values in the 2- or 3-in. dimension lumber used for framing. In response to this trend, many of the dimension grades of lumber have been redefined to make them stress grades. At the same time, not all dimension lumber is in stress grades, and engineers have demanded more information on the strength values in such lumber. That demand has led to the studies reported here.