Lumber has been graded visually for many decades as a reliable way of assuring consistent quality. A second grading system, using machines to sort the lumber into grades, has been in use for over 30 years. One of these lumber products, machine-stress rated [MSR] lumber, has been used for many years in highly demanding engineered applications. Recently, a similar product called machine evaluated lumber [or MEL] has also become available. Both MSR and MEL are specialty lumber products falling within the size parameters of dimension lumber.
The precision of machine grading results in more efficient use of the forest resource. This translates into a set of cost-competitive products that extend the use of lumber into high strength applications. MSR lumber is favoured particularly by specialized users such as truss manufacturers where higher strength per volume of lumber and reliability resulting from measured design values is required.