MSR (Machine Stress-Rated Lumber)
Lumber graded by machine measurement of stiffness (modulus of elasticity) rather than visual inspection alone. Provides more precise and consistent structural properties than visual grading.
In Detail
MSR lumber passes through a machine that measures its bending stiffness (MOE) non-destructively. Pieces are then assigned an MSR grade designation like 2400f-2.0E, meaning 2,400 psi bending strength and 2.0 million psi modulus of elasticity. MSR lumber is used in trusses, engineered applications, and wherever consistent mechanical properties are critical.