Engineered Lumber Glossary

Decorative Plywood
Plywood used for wall paneling, cabinet construction or furniture. It uses softwood veneers or for the substrate, onto which high quality hardwood veneer is glued.

Finger-Jointed Lumber
Short lengths of wood that have been machined with finger joints at the ends so they mate perfectly when glued together. Finger jointing adds surface area to the joint which greatly increases its strength. By salvaging short, knot-free lengths from low quality lumber to make long lengths of higher grade lumber, finger jointed wood reduces waste and adds to the sustainability and renewability of the wood.

Glulam
Glue-laminated timber refers to large, structural members made by gluing together pieces of dimension lumber. It’s a unique structural material because it can be formed into many curved shapes and the sizes are limited only by transportation restrictions. It is generally used for columns and beams, and frequently for curved members loaded in combined bending and compression. Glulam also is used as an exposed architectural product or it can be hidden or left unfinished to only serve a structural role.

I-Joists
Wood I-joists are a structural engineered wood product often used for joists and rafters in residential and commercial construction. I-joists are made by gluing solid sawn lumber or laminated veneer lumber (LVL) flanges to a web made of plywood or oriented strand board (OSB). I-joists exhibit uniform stiffness, strength and are lightweight.

Laminated Veneer Lumber (LVL)
LVL has several layers of wood veneers and adhesive. First used during World War II to make airplane propellers, it’s been used since the mid-1970's to build beams and headers for buildings where high strength, stability and reliability are required.

Machine Stress Rated Lumber
Standard lumber is load rated based on dimension and visual inspection. Engineered lumber is also rated according to its design strength. But the only way to be absolutely certain that a given piece of lumber will meet its rating is to stress it mechanically. Machine Stress Rated (MSR) lumber is just that: lumber that has been mechanically stressed to its rated load before it is used in a project. The benefit is lumber that is less likely to fail mechanically once installed. This results in fewer expensive onsite repairs.

Medium Density Fiberboard (MDF)
A wood-based panel made from fine cellulose fibers combined with a synthetic resin or other suitable bonding system, which is then joined together under heat and pressure. Because of the fineness of the fibers, it forms and machines smoothly and precisely, making it an ideal substrate for thin laminates.

Oriented Strand Board (OSB)
Wood panel used as a sheathing material for floors, walls and roofs. OSB has grown enormously in popularity over the past decade because it’s economical and has excellent racking resistance, which is, the ability to strengthen a building against horizontal loads such as extreme winds or the forces of earthquakes.

Parallel Strand Lumber
A high-strength structural composite marketed under the trade name Parallam®. PSL is comparable in strength to laminated veneer lumber. Both products are often grouped under the heading Structural Composite Lumber (SCL). PSL is made from long strands of wood chopped from wood veneer. This process allows the removal of growth defects from the raw material. PSL is then made into large billets and sawn into stock and custom sizes.

Particleboard
A panel product made from sawdust and other residue left over from the manufacture of lumber and other wood products. Since it's derived from other wood products, particleboard is an environmentally friendly choice.

Plywood
An engineered panel product consisting of veneers glued together so the grain direction of the ply is perpendicular to that of adjacent plys. This gives plywood equal strength in its length and width. 

Rim Board
Board used to surround I-joist floor-joists. Rim boards mount between sills and wall plates. In addition to transferring lateral and vertical loads to the frame of the house, RIM Board can be ordered to match the depth of I-Joist framing members—something that conventional lumber typically does not match.

Structural plywood
Used for construction and industrial applications, made with waterproof glue to maintain strength in exterior applications.

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