Engineered Lumber

By Kenton Shepard

Engineered wood products use recycled/reconstituted wood chips or strands and finger-jointing (the gluing of larger pieces together) to produce a variety of building products such as structural framing lumber and trim material.

Waste wood and entire trees can be used to produce products regardless of species and age.

Engineered wood is generally straighter, more stabile and structurally consistent than dimensional lumber. In joist and rafter applications, the reconstituted products are particularly useful because they can span long distances with less sagging than similarly-sized conventional lumber.

Cost

Engineered wood is generally more expensive than dimensional lumber, but cost is offset to some degree by labor savings and improved quality.

Types of Enginered Lumber

Finger-jointed Studs

Finger-jointed studs are manufactured by milling tightly fitting joints in short pieces of lumber which would otherwise be considered scrap. These short pieces are glued together in a manner which results in the joints being stronger than the wood. Joints will lose strength if material is not protected from weather.

Source: Kenton Shepard

Finger-jointed studs

I-beams

I-beams are framing members typically used as floor joists and sometimes as rafters. They’re “I” shaped in cross section, dimensionally stable, available in a variety of structural ratings and are produced in lengths up to 60 feet. They consist of a plywood or oriented-strand-board (OSB) web to which is attached a top and bottom chord usually either 2x2, 2x3 or 2x4 depending on the structural rating of the joist. 

Source: Kenton Shepard

                        I-beams are light                    ...can be used for joists                                ...or rafters 

"The versitility of I-beams"

Glu-Lams

Glu-Lams are beams manufactured by gluing together layers of dimensional lumber. Engineered beams are typically more stable and stronger than similar-sized dimensional beams and can be manufactured with a camber. Glu-Lam beams can also be manufactured in large sizes which would be much more expensive if milled from a solid piece of wood. Glu-Lams are often left exposed. Building beams by laminating smaller pieces of dimensional lumber allows for more efficient use of wood and helps save trees.

Source: Kenton Shepard

Glulams supporting a bridge

Parallams

Parallams are engineered wood beams manufactured by gluing together aligned wood strands and bonding them using a microwave process.

Source: Kenton Shepard

Parallams

Microlams

To produce Microlam® Laminated Veneer Lumber (LVL), sheets of veneer peeled from logs are carefully dried, ultrasonically graded for strength, and evaluated to ensure uniform thickness and moisture content. The sheets are coated with adhesive, layered, and subjected to heat and pressure to achieve a permanent bond. As with I-beams, Microlams are available in long lengths.

Source: Kenton Shepard

   Heavier and stronger than I-joists                             Microlams in a lumber yard

Oriented Strand Board (OSB)

OSB has replaced plywood in many applications. It’s manufactured using waterproof, heat-cured adhesives and rectangular-shaped, aligned wood strands.  Strand direction changes in each layer in a manner similar to the way the veneers within a sheet of plywood alternate direction. This results in a structural, engineered-wood panel that shares many of the strength and performance characteristics of plywood. Available from lumber yards in 4’x 8’, 4’x 9’ and 4’x10’ lengths.

Source: Kenton Shepard

OSB is commonly used as structural sheathing for walls, floor and roofs

Recycled-content Decking Material

T h e re are two types of recycled content decking: plastic lumber and composite lumber. Recycled plastic lumber contains only recycled plastic resins, while composite lumber is made by combining recycled wood fiber and recycled plastic resins that are then formed into deck boards.

Source: Kenton Shepard

Recycled-content decking comes in a variety of textures and color 

Timberstrand

Timberstrand is used for rim joist because it’s designed for use in compression only. It should never be used as a common joist to span open sections.

Source: Kenton Shepard

Timberstrand

Borate-Treated Lumber

For many years Western Hemlock was pressure-treated (wolmanized lumber) with toxic chemicals including arsenic and chromium in order to make it resistant to damage from mold and decay fungi and wood-destroying insects. In 2004, its use was banned by the EPA from most residential projects. Since 2004, the most common type of pressure-treatment for wood has been Alkaline Copper Quat (ACQ) which still requires the use of a dust mask and gloves for safe use, and special connectors and fasteners to resist corrosion.

Borate-treated wood resists mold and decay fungi, wood destroying insects and is non-toxic. At this time it's use is still being limited to locations above-ground and with no contact with liquid water. It can be recognized by its bluish tint and lack of slotted markings common to wolmanized and ACQ-treated lumber.

Source: Kenton Shepard

Borate-treated lumber

Borate rods

Borate rods are rods designed to be inserted into holes drilled into wood. When moisture in wood reaches levels at which decay fungus become active (approximately 20%) the rods dissolve and the borate diffuses through the wood, effectively preventing wood decay. When moisture levels fall below 20%, the borate rod solidifies. Borate rods are especially useful for treating log homes and in areas such as exterior post bases (rods inserted into holes drilled into the bottoms of posts).