Laminated veneer lumber - is an engineered wood product created by layering dried and graded wood veneers with waterproof adhesive into blocks of material known as billets. Cured in a heated press, LVL is typically available in various thicknesses and widths and is easily worked in the field using conventional construction tools. LVL is also known as structural composite lumber (SCL).
I-joist rafters are blocked at the point which they bear on exterior wall headers. The blocking assures the that the I-joist cannot rotate from their upright position.