What is MSR lumber?
MSR, or machine stress-rated, lumber is manufactured to conform to the National Lumber Grades Authority’s product standard and is graded mechanically. Lumber is fed into mechanical evaluating equipment, which measures and records stiffness, assesses strength and applies an MSR grade mark on the lumber. MSR lumber is also visually checked for properties other than stiffness which might affect the suitability of a given piece.
