A horizontal structural member used to support and stabilize I-joists along their length. Girders used to support I-joist floor assemblies are typically made from glued-laminated lumber, parallel strand lumber, or multiple pieces of laminated veneer lumber (LVL).

LVL Girders
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).
Floor joists are held in place where they bear on the exterior wall by a band-joist or rimboard.
An I-joist is supported by Laminated Veneer Lumber (LVL) attached by a joist hanger.
A flush mounted LVL header supporting I-joist floor framing in metal joist hangers will not be obvious once the gypsum wallboard ceiling is attached.
Plywood floor sheathing is used in combination with I-joists and an LVL girder.
Laminated veneer lumber is placed into a metal hanger and supported by another LVL girder.
Laminated veneer lumber is manufactured from multiple layers of wood veneer layed-up with the grain parallel to the length of the lumber.
I-joists floor framing bears in metal joist hangers along side a multi-ply laminated veneer girder.
Beams and Joists Intersecting
PSL Girders
Parallel strand lumber (PSL) is a high strength structural composite lumber product manufactured by gluing strands of wood together under pressure. It is a proprietary product marketed under the trade name ParaIlam®.
Parallel strand lumber (PSL) girders.
Glulam Girders
Glulam is a stress-rated engineered wood product comprised of wood laminations, or "lams," that are bonded together with strong, waterproof adhesives. Glulam components can be avariety of species, and individual "lams" are typically two inches or less in thickness. ANSI/AITC A190.1 includes requirements for sizes, grade combinations, adhesives, inspection, testing, and certification of structural glued laminated timber products.
Glulam beams are becoming more common in residential construction.