The special grade of lumber used for glulam, lamstock, is received and stored at the laminating plant under controlled conditions (see Figure 3.7 below).
Prior to glulam fabrication, all lumber is visually graded for strength properties and mechanically evaluated to determine the modulus of elasticity (E). These two assessments of strength and stiffness are used to determine where a given piece will be situated in a beam or column.
For example, high strength pieces are placed in the outermost laminations of a beam where the bending stresses are the greatest. This blending of strength characteristics is known as grade combination and ensures consistent performance of the finished product.
Figure 3.7: Manufacture of Glulam