What Is Engineered Wood? Advantages and Disadvantages

Dec. 23, 2024

What Is Engineered Wood? Advantages and Disadvantages

Construction Materials

What Is Engineered Wood?

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Engineered wood boards are generally made from the same hardwoods and softwoods used to manufacture lumber, but mixed with additives like adhesives. This type of wood often utilizes waste wood from sawmills, and are treated through chemical or heat processes to produce wood that meets size requirements that are hard to find in nature.

Engineered wood is used in a variety of applications, from home construction to commercial buildings to industrial products.

&#;Engineered lumber is lumber that although it comes from wood, it&#;s been processed to be something slightly different and perform in a different, oftentimes better way than what just the raw wood would perform.&#; -Professional builder Jordan Smith

7 Popular Types of Engineered Wood

Engineered wood products are available as framing members&#;beams, for example&#;and sheet goods, which can be used as sheathing or flooring.

1. Laminated Veneer Lumber (LVL)

Made of wood veneers that are compressed together with resins and glues, LVL is a high density engineered wood product used in framing. LVL is very strong, but has only one strength axis, because its veneers are stacked with the grain running in the same direction. This means you can only load LVL in one direction.

2. Laminated Strand Lumber (LSL)

Made of small strips of wood&#;strands&#;that are placed in a dense, angled pattern, LSL is a high quality engineered wood product that can be an even higher density and stronger than LVL. It is composed of about 95% wood fiber and 5% resin. LSL is very resistant to weight and torsion because of the angled pattern in which the wood strips are placed. LSL is also expensive&#;it&#;s about 3x the cost of dimensional lumber.

3. Oriented strand board (OSB)

This type of sheet good is formed by combining wood strands or flakes with adhesives and then compressing them. It is manufactured in wide mats and is good for load-bearing applications such as flooring and roof decking. All OSB isn&#;t created equal&#;some is sanded (like Advantech or Legacy premium subfloor), and other boards are not. Some OSB is moisture resistant, other boards are not. Make sure that you are using premium grade OSB if there&#;s any chance of it experiencing whether.

It is important to note that for OSB (and plywood), you want to gap all of your ends, so that when it expands and contracts with moisture in the long direction, you aren&#;t causing it to buckle. However, on the tongue and groove of premium subflooring, there is a pre-manufactured stop that gives you the &#;-inch gap in between boards.

4. Plywood

A sheet good manufactured from thin layers (or &#;plies&#;) or wood veneer that are glued together. Plywoods have several benefits to builders, since they are made by binding resin and wood fiber sheets to form a composite material whose &#;cross graining&#; property provides dimensional stability and makes the strength of the panel consistent in all directions.

Remember to gap all of your ends with plywood, because it does still expand and contract with moisture.

Engineered wood is used in a variety of applications, from home construction to commercial buildings to industrial products.

&#;Engineered lumber is lumber that although it comes from wood, it&#;s been processed to be something slightly different and perform in a different, oftentimes better way than what just the raw wood would perform.&#; -Professional builder Jordan Smith

7 Popular Types of Engineered Wood

Engineered wood products are available as framing members&#;beams, for example&#;and sheet goods, which can be used as sheathing or flooring.

1. Laminated Veneer Lumber (LVL)

2. Laminated Strand Lumber (LSL)

3. Oriented strand board (OSB)

4. Plywood

Remember to gap all of your ends with plywood, because it does still expand and contract with moisture.

A plywood sheet has two face veneers, so if you see a sheet graded as &#;AB&#; that means it is A-quality on one side and B on the other.

A:
This is the highest quality plywood with a smooth surface free of knots and repairs.
B:
This grade is largely free of knots, though some tight ones (under 1 inch) are acceptable.
C:
C grade plywood may include knots up to 1.5 inches and knotholes under 1 inch.
D:
The lowest grade can have knots and knotholes up to 2.5 inches. In general, any defects have not been repaired with D grade plywood.
X:
An X is used to indicate exterior plywoods. A grade of CDX would mean a plywood is C grade on one veneer, D on the other, and designed for outdoor use.

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5. Medium density fiberboard (MDF)

MDF is made by breaking down hardwood and softwood pieces into fibers, which are combined with wax and resin binders, and formed into panels by applying high temperatures and pressure. It is usually more dense than plywood, and is more dense than oriented strand board, but just like OSB, there are grades that can withstand water and weather and other grades that cannot.

6. Composite board

This engineered wood term includes MDF and oriented strand board. It refers to a wood engineered with both plastic content and wood fiber that has been extruded and heated. It&#;s also known as engineered wood. It is easy to install, cost-effective, and good for incorporating into sustainable design, since it can be made of recycled material using fewer trees.

7. Cross-laminated timber (CLT)

This wood panel product is made from gluing together layers of solid sawn lumber. It is strengthened by layering each board perpendicular to the next and glued on the wide faces of each board. The thicknesses of the panels can easily be increased, which makes it a design-flexible material. It can be a good insulator, since it&#;s made of multiple layers of wood.

Learn all about the properties of wood and how wood is used in construction in the MT Copeland course on Wood Materials. Taught by professional builder Jordan Smith, the course covers topics that range from I-joists to shear strength.

Pros and Cons of Engineered Wood

&#;Engineered beams are a great way of getting the strength while keeping the cost and size low.&#;-Professional builder Jordan Smith

Advantages of engineered wood over solid wood

Engineered wood has become a popular type of flooring because of its many advantages.

Engineered wood is sustainable, because it allows you to achieve (or exceed) the same density and strength of old growth timber, but with lumber made from young trees. It also reduces waste, because it uses all parts of the tree&#;even defects or pieces leftover from cutting dimensional lumber.
Engineered wood can be stronger than dimensional lumber because of its high density and layers of grain running in different directions.
Engineered beams come in almost any size&#;you can get bigger members because they&#;re created by composite, rather than having to be cut from single trees.
Some engineered wood can resist warping and splitting more than dimensional lumber.

Disadvantages of engineered wood over solid wood

Engineered wood is often less aesthetically pleasing than real wood, because of the visible wood strips (rather than the clean, natural look of solid timbers). One exception to this is architectural-grade glulam
Engineered wood&#;especially LSL&#;can be much more expensive than dimensional lumber.

MT Copeland offers video-based online classes that give you a foundation in construction fundamentals with real-world applications. Classes include professionally produced videos taught by practicing craftspeople, and supplementary downloads like quizzes, blueprints, and other materials to help you master the skills.

History of APA, Plywood, and Engineered Wood

APA &#; The Engineered Wood Association is the nonprofit trade association of the U.S. and Canadian engineered wood products industry. Based in Tacoma, Washington, the Association is comprised of and represents manufacturers of structural plywood, oriented strand board (OSB), cross-laminated timber, glued laminated (glulam) timber, wood I-joists, and laminated veneer lumber (LVL).

APA was founded in as the Douglas Fir Plywood Association to advance the interests of the burgeoning Pacific Northwest plywood industry. Adhesive and technology improvements eventually led to the manufacture of structural plywood from Southern pine and other species, and in the Association changed its name to American Plywood Association (APA) to reflect the national scope of its growing membership.

The Association&#;s membership expanded again in the early s with the introduction of oriented strand board (OSB), a product the Association helped bring to market through development of new panel performance standards. A decade later, APA accommodated manufacturers of non-panel engineered wood products, such as glulam timber, wood I-joists and laminated veneer lumber.

To better reflect the broadening product mix and geographic range of its membership, the Association changed its name again in to APA &#; The Engineered Wood Association. The acronym &#;APA&#; was retained in the name because it was so widely known and respected in the marketplace.

History of Plywood

Ancient Origins of Plywood

Archeologists have found traces of laminated wood in the tombs of the Egyptian pharaohs. A thousand years ago, the Chinese shaved wood and glued it together for use in furniture. The English and French are reported to have worked wood on the general principle of plywood in the 17th and 18th centuries. And historians credit Czarist Russia for having made forms of plywood prior to the 20th century as well. Early modern-era plywood was typically made from decorative hardwoods and most commonly used in the manufacture of household items, such as cabinets, chests, desk tops and doors. Construction plywood made from softwood species did not appear on the scene until the 20th century.

Plywood Patented, Then Forgotten

The first patent for what could be called plywood was issued December 26, , to John K. Mayo of New York City. A re-issue of that patent, dated August 18, , described Mayo&#;s development as follows: &#;The invention consists in cementing or otherwise fastening together a number of these scales of sheets, with the grain of the successive pieces, or some of them, running crosswise or diversely from that of the others&#;&#; Mayo may have had a vision, but apparently not much business sense, since history does not record that he ever capitalized on his patents.

: An Industry is Born

In , the city of Portland, Oregon was getting ready to host a World&#;s Fair as part of the 100th anniversary celebration of the Lewis and Clark Expedition. Several local businesses were asked to prepare exhibits for the event, including Portland Manufacturing Company, a small wooden box factory in the St. Johns district of the city. Part owner and plant manager Gustav Carlson decided to laminate wood panels from a variety of Pacific Northwest softwoods. Using paint brushes as glue spreaders and house jacks as presses, several panels were laid up for display. Called &#;3-ply veneer work,&#; the product created considerable interest among fairgoers, including several door, cabinet and trunk manufacturers who then placed orders. By , Portland Manufacturing had installed an automatic glue spreader and a sectional hand press. Production soared to 420 panels a day. And an industry was born.

From Doors to Running Boards: The First Plywood Markets

During its first 15 years the softwood plywood industry relied primarily on a single market&#;door panels. But in , &#;super salesman&#; Gus Bartells of Elliott Bay Plywood in Seattle began generating customers in the automobile industry. Bartells had earlier established the first plywood dealerships around the country, and was equally successful in getting car manufacturers to use plywood for running boards. The market took off and the industry enjoyed steady growth during the Jazz Age. By , there were 17 plywood mills in the Pacific Northwest and production reached a record 358 million square feet (3/8-inch basis).

A Technological Breakthrough: Waterproof Adhesive

Lack of a waterproof adhesive that would make plywood suitable for exterior exposure eventually led automobile manufacturers to switch from plywood to more durable metal running boards. A breakthrough came in when Dr. James Nevin, a chemist at Harbor Plywood Corporation in Aberdeen, Washington, finally developed a fully waterproof adhesive. This technology advancement had the potential to open up significant new markets. But the industry remained fragmented. Product quality and grading systems varied widely from mill to mill. Individual companies didn&#;t have the technical or in most cases marketing resources to research, develop and promote new uses for plywood. The industry looked for help from its newly formed trade association, the Douglas Fir Plywood Association.

Founding of the Douglas Fir Plywood Association

Several failed attempts to establish a plywood association were made in the early years of the industry. Finally, on May 16, , several fir plywood manufacturers met at the old Portland Hotel to discuss the advisability of adopting certain trade practices before the industry would be forced to do so under the Depression-era National Recovery Act. The act was later declared unconstitutional but for a time put pressure on the plywood industry to organize. A month of negotiations followed and on June 13, , the Douglas Fir Plywood Association held its first regular meeting at the Winthrop Hotel in Tacoma, Washington. The new association struggled until, in , it hired a legendary business development guru, W. E. &#;Diff&#; Difford.

Standardization and Improved Quality Testing Boost Sales

The Douglas Fir Plywood Association was among the first to take advantage of a law that permitted registration of industrywide trademarks, which allowed plywood to be promoted as a standardized commodity rather than by individual brand names. That same year, FHA accepted exterior plywood, based in part on a new Commercial Standard that included performance tests for both interior and exterior plywood. These developments helped clear the way for more successful promotion of plywood&#;s benefits to the construction industry. &#;Dri-Bilt With Plywood&#; became a familiar advertising slogan. More than a million low-cost Dri-Bilt homes were constructed featuring DFPA-trademarked PlyScord subfloors and sheathing, PlyWall ceilings and walls, PlyPanel built-ins, and PlyShield siding. In , the association sponsored &#;The House in the Sun,&#; the first of many plywood demonstration houses. Plywood&#;s growing reputation as a strong and durable construction material was soon put to the extreme test by war.

Plywood Goes to War

World War II was a proving ground for plywood. The product was declared an essential war material and production and distribution came under strict controls. The industry&#;s war-time mills&#;by this time numbering about 30&#;produced between 1.2 and 1.8 billion square feet annually. Plywood barracks sprung up everywhere. The Navy patrolled the Pacific in plywood PT boats. The Air Force flew reconnaissance missions in plywood gliders. And the Army crossed the Rhine River in plywood assault boats. There were thousands of war accessories made of plywood&#;from crating for machinery parts, to huts for the famed Seabees in the South Pacific, to lifeboats on hundreds of ships that kept supply lines open in the Atlantic and Pacific.

The Post-War Boom

With the war ended, the industry geared up to meet growing demand in the booming post-war economy. In , the industry&#;s 30 mills produced 1.4 billion square feet of plywood. By , the industry had grown to 101 mills and production approached 4 billion square feet. That same year, the Stanford Research Institute predicted that demand for plywood would rise to 7 billion feet by &#;21 years into the future. Although some were skeptical, production rocketed to 7.8 billion feet in just five years, and by U.S. production alone exceeded 16 billion square feet, more than double the forecast.

Plywood Goes North

With its rich forest resources, it was only natural that Canada should join what eventually would become a truly North American plywood industry. The first Canadian plywood was produced in at Fraser Mills, New Westminster, British Columbia, but it wasn&#;t until that a second mill was opened&#;by the H.R. MacMillan Company. In , five Canadian companies founded the Plywood Manufacturers Association of British Columbia (PMBC), which eventually evolved into the Canadian Plywood Association (CANPLY). The Canadian Standards Association published the first Canadian Plywood Standard in based on specifications developed by PMBC.

The Rise of Southern Pine

For more than a half century the softwood plywood industry was located exclusively in the Pacific Northwest and British Columbia using the region&#;s vast supply of Douglas fir. Until mid-century, it was not known how to effectively glue together veneer from softwood species grown in other regions. But research and development efforts changed that in the late s and early 60s, and in Georgia-Pacific Corporation opened the first southern pine plywood mill, in Fordyce, Arkansas. The Douglas Fir Plywood Association changed its name that same year to reflect the fact that the plywood industry was now national in scope. Today, some two-thirds of all U.S. plywood is produced in the South.

Technology Marches On

Plywood is often called the original engineered wood product because it was one of the first to be made by bonding together cut or refashioned pieces of wood to form a larger and integral composite unit stronger and stiffer than the sum of its parts. Cross-laminating layers of wood veneer actually improve upon the inherent structural advantages of wood by distributing along-the-grain strength of wood in both directions. This idea of &#;reconstituting&#; wood fiber to produce better-than-wood building materials has led in more recent times to a technological revolution and the rise of a whole new engineered wood products industry. In the late s and early 80s, for example, the plywood principle gave rise to what today is a worldwide oriented strand board, or OSB, industry. Instead of solid sheets of veneer, OSB is made of small wood strands that are glued together in cross-laminated layers. Other engineered wood products today include wood I-joists, glued laminated timber, laminated veneer lumber, and oriented strand lumber. These products not only yield superior performance properties, but also make better use of precious forest resources. And it all began with plywood.

History of Glulam

Glulam was first used in Europe in the early s. A patent from Switzerland signaled the true beginning of glued laminated timber construction. One of the first glulam structures erected in the US was a research laboratory at the USDA Forest Products Laboratory in Madison, Wisconsin. The structure was erected in and is still in service today.

A significant development in the glulam industry was the introduction of fully water-resistant phenol-resorcinol adhesives in . This allowed glulam to be used in exposed exterior environments without concern of glueline degradation.

The first US manufacturing standard for glulam was Commercial Standard CS253-63, which was published by the Department of Commerce in . The most recent standard is ANSI Standard A190.1.

Wood I-joists and Rim Board®

Originally commercialized by the Trus Joist Corporation (now a Weyerhaeuser company) in the s, engineered wood I-joists owe their beginning, at least in part, to a publication developed by the Douglas Fir Plywood Association, (the precursor to APA &#; The Engineered Wood Association) in entitled DFPA Specification BB-8, Design of Plywood Beams. This specification, later published as Plywood Design Specification Supplement 2, Design and Fabrication of Glued Plywood-Lumber Beams, outlined the original design procedures that ultimately provided the basis for current design recommendations.

The first universally recognized standard for wood I-joists was, and still is, ASTM D, Standard Specification for Establishing and Monitoring Structural Capacities of Prefabricated Wood I-Joists. This consensus standard provides guidelines for the evaluation of mechanical properties, physical properties, and quality of wood I-joists and is the current common testing standard for I-joists. However, since ASTM D does not specify required levels of performance, individual manufacturers of I-joists generally have their own proprietary company standards that govern the everyday production practice for their products. As the history of other building materials such as plywood and oriented strand board (OSB) has shown, some degree of standardization of the industry is inevitable. Also inevitable is that along with standardization will come greater manufacturing efficiencies and greater use in construction.

To fill this need for standard performance levels, APA, in conjunction with several I-joist manufacturers, has developed performance-based standards for performance-rated wood I-joist products. The first such APA performance standard is for the use of wood I-joists in residential floors, designated as PRI-400, although roof tables and details have also been developed for the PRI-400 joists. It should be noted that this is a voluntary standard and not all I-joist manufacturers have chosen to produce PRI-400 products.

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