Engineered Lumber Buying Guide

Getting Started

Engineered Lumber is a manufactured product including natural wood species with adhesives and glues to create a structurally superior product.

Plywood

Plywood is an engineered product and considered a general construction material as it is used for sheathing, subfloors and various applications in construction. Plywood is constructed from two thin sheets of softwood, hardwood or a combination of both with a sandwiched layer of wood chips running vertical to the grain of the top and bottom layers. The chips are glued and the sheet is baked at high temperatures to create a strong sheet. Three layers, or plys, are standard but extra layers may be added to create a stronger sheet. Plywood is tested for tensile strength, can be treated for fire and water resistance. Produced in 4X8 foot sheets.

• Structural plywood is used where strength is needed such as flooring.

• External plywood is not used for structural purposes and has a finished panel and is used for wall cladding, or exterior door panels.

• Internal plywood is not used for structural purposes, has a finely finished top panel and is used for walls and ceilings.

• Marine plywood is treated with preservatives, paint or varnish so it won’t delaminate.

• Grades of plywood run from A, B, C, D, or N. N has very few and little knots or defects in graining while D may have many of these. A, B, and C will range from few to a few more. C-D is interior rated with a top sheet with few defects and a D undersheet that may have more so. Also, the adhesive used is appropriate for interior use.

Oriented Strand Board

Oriented Strand Board (OSB) is used for sheathing and underlayments. Created from chips and flakes of wood oriented at 90 degree angles from each other and set in a resin that is baked at high temperatures to produce a strong sheet. Water resistant, OSB is tested for strength by how much weight it will hold. Available in 4X8 foot sheets, ¼-inch to ¾-inches thick. Tongue and groove designs are manufactured.

Finger Jointed Lumber

Finger jointed lumber is used when the lengths of 22-feet to 24-feet are needed. Dimensional lumber is cut to small lengths under 2-feet and with finger joints are glued together producing stronger lengths up to 36-feet long.

Structural Composite Lumber

Structural Composite Lumber is a category of engineered products formed into billets by layering dried and graded wood strands, veneers or flakes in a moisture resistant adhesive. The billets can be sawn into sizes specified for construction materials. Due to the engineering process, these materials will not warp or split.

• Laminated Veneer Lumber (LVL) is produced from thin layers of wood that are bonded together with the grain parallel to the long direction. Since it is manufactured under controlled situations with jointed or lapped veneers, it is engineered to be stronger, more uniform, and straighter than traditional lumber. It can be sawn and used as flanges on engineered i-joists. Frequently specified for headers, hip and valley rafters and ridgeboard.

• Parallel Strand Lumber (PSL) is engineered from clipped long strand veneers that are laid parallel and bonded with adhesives. The strength-to-thickness ratio is about 300. Designed for use on long, clear spans, PSLs can be used as beams, headers and even load-bearing columns.

• Laminated Strand Lumber (LSL) is composed of flaked wood strands combined with adhesives with a length-to-thickness ration of about 150. The strands and adhesive are formed into a large mat or billet and pressed. Cut in lengths up to 30-feet as studs, sill plates, and headers, they can be used for creating tall walls without warping and twisting.

I-Joists

I-Joists are engineered as strong yet lightweight for framing in residential and light commercial construction. Shaped like a capital I, the I-joist has a top and bottom flange, often created from sawn LVL, with a center web of plywood or OSB. Used for floor and roof framing, I-joists are engineered for longer spans, and will not crown or warp. Common depths are 9-1/2”, 11-7/8” 14” and 16”; flanges vary in width from 1-1/2” to 3-1/2”.

Glulams

Glulams are strong structural beams often left exposed due to their beauty. Created by using durable, moisture-resistant adhesives with wood laminations running parallel to the length of the design. Available in custom or stock sizes, Glulams are used where a long run is desired, such as in garage door headers, ridge beams and large cantilevered beams. Stock sizes are 3-1/8”, 3-1/2”, 5-1/8”, 5-1/2” and 6-3/4”. Created in premium, architectural, industrial and framing classifications.

Rim Board

Rim Board is rated by the APA-The Engineered Wood Association and is manufactured for strength, dimensional stability and structural reliability of plywood, OSB, glulam, or LVL in lengths up to 24’. Designed to match the depth of I-joists, Rim Board is used in floor systems between the sill plate and bottom plate of a wall, or between the top plate and bottom plate of two wall sections.

Cross-Laminated Timber

Cross-Laminated Timber is engineered for use in multi-family and commercial construction. Manufactured from several layers of kiln-dried lumber boards stacked in alternating directions and pressed with structural adhesives.