Laminated veneer lumber
   HOME

TheInfoList



OR:

Laminated veneer lumber (LVL) is an
engineered wood Engineered wood, also called mass timber, composite wood, man-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibres, or veneers or boards of woo ...
product that uses multiple layers of thin
wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...
assembled with
adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...
s. It is typically used for headers,
beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized grou ...
s, rimboard, and edge-forming material. LVL offers several advantages over typical milled
lumber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, wi ...
: Made in a factory under controlled specifications, it is stronger, straighter, and more uniform. Due to its composite nature, it is much less likely than conventional lumber to warp, twist, bow, or shrink. LVL is a type of structural composite lumber, comparable to
glued laminated timber Glued laminated timber, commonly referred to as glulam, is a type of structural engineered wood product constituted by layers of dimensional lumber bonded together with durable, moisture-resistant structural adhesives so that all of the grain run ...
(glulam) but with a higher allowable stress.


History

Structural composite lumber products, including LVL, are a relatively recent innovation. They are the result of new technology and economic pressure to make use of new species and smaller trees that cannot be used to make solid sawn lumber. While
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
became widespread by the early 20th century, the invention of LVL was not until the 1980s after the invention of oriented strand board. The American Wood Council's National Design Specification for Wood Construction is generally updated on a 3- to 5-year cycle. The 1991 release is the first release which mentions LVL. LVL is mentioned as a subcategory of structural glued laminated timber. The first explorations into engineered lumber happened during World War II in the United States. In 1942, an increased demand for wood caused a sudden timber shortage. The war industry utilized a panel material developed by the Homasote Company of Trenton, New Jersey, made of wood pulp and ground newspaper, to be used in place of siding and sheathing for buildings. The invention of laminated veneer lumber as known today can be attributed to Arthur Troutner. While glue laminated wood veneers were in use since the middle of the 19th century on a small scale for furniture and pianos, Troutner was the first to develop a laminated veneer lumber of a scale large enough to be used in construction. In 1971 "Micro=Lam LVL" was introduced. "Micro=Lam LVL" consisted of laminated veneer lumber billets wide, thick, and long. Troutner proved the structural capabilities of his Micro=Lam product by building a house in Hagerman, Idaho, using beams made of Micro=Lam. Most corporations considered Troutner's invention to be a niche product and it was not until the mid 1980s when logging became an environmental concern and corporations moved toward engineered lumber that LVL became widespread in use.


Qualities

Laminated veneer lumber is similar in appearance to
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
, although in plywood the veneers switch direction while stacking and in LVL the veneers all stack in the same direction. In LVL, the direction of the wood grain is always parallel to the length of the billet. The stacking of these veneers into a complete board, called a billet, creates a single piece of LVL sharing a common direction of wood grain. LVL is typically rated by the manufacturer for elastic modulus and allowable bending stress. Common elastic moduli are ; ; and ; and common allowable bending stress values are ; and . Although the creation of LVL is often proprietary and thus its make-up is largely dependent on individual manufacturers, in general one cubic meter of North American lumber is composed of 97.54% wood, 2.41% of
phenol formaldehyde resin Phenol formaldehyde resins (PF) or phenolic resins (also infrequently called phenoplasts) are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. Used as the basis for Bakelite, PFs were the first commerc ...
, 0.02% of phenol-resorcinol-formaldehyde resin, and 0.03% fillers.http://www.icc.es.org/Reports/pdf_files/load_file.cfm?file_type=pdf&file_name=ESR-1387.pdf


Manufacturing

LVL is commonly manufactured in North America by companies that also manufacture
I-joist An engineered wood joist, more commonly known as an I-joist, is a product designed to eliminate problems that occur with conventional wood joists. Invented in 1969, the I-joist is an engineered wood product that has great strength in relation to ...
s. LVL is manufactured to sizes compatible with the depth of I-joist framing members for use as beams and headers. Additionally, some manufacturers further cut LVL into sizes for use as chord-members on I-joists. In 2012, North American LVL manufacturers produced more than 1.2 million cubic metres (43.4 million cubic feet) of LVL in 18 different facilities, and in 2013 the production increased by more than 14%. It is not coincidental that LVL mills are often co-located with I-joist manufacturing facilities as many builders use a combination of I-joists and LVL in floor and roof assemblies.


Use

Because it is specifically sized to be compatible with
I-joist An engineered wood joist, more commonly known as an I-joist, is a product designed to eliminate problems that occur with conventional wood joists. Invented in 1969, the I-joist is an engineered wood product that has great strength in relation to ...
floor framing, residential builders and building designers like the combination of I-joist and LVL floor and roof assemblies. LVL is considered to be a highly reliable building material that provides many of the same attributes associated with large sized timbers. LVL can also be used in combination with gluelam as an outer gluelam tension lam to increase the strength of the gluelam beam. However, due to the fact that the assembly adhesives limit the penetration of chemicals typically used to treat outdoor-rated lumber, LVL may not be suitable for outdoor load-bearing use. The breakdown of LVL end uses in North America is 33% new single family residential construction, 25% residential renovations and upkeep, 8% new non-residential construction and 34% manufacturing furniture and other products.


Structural composite lumber

LVL belongs to the category of engineered wood called structural composite lumber. Other members of this category are
parallel strand lumber Parallel-strand lumber (PSL) is a form of engineered wood made from parallel wood strands bonded together with adhesive. It is used for beams, headers, columns, and posts, among other uses. The strands in PSL are clipped veneer elements having a ...
(PSL) and laminated strand lumber (LSL). All members of this category are strong and predictable, and are thus interchangeable for some applications. PSL is made from veneers that are cut up into long strands and oriented parallel to its length before being compressed into its final shape. LSL is also made from strands rather than veneer, although the strands are shorter and aligned with less precision than PSL and is created as billets that are like a thick version of
oriented strand board Oriented strand board (OSB) is a type of engineered wood similar to particle board, formed by adding adhesives and then compressing layers of wood strands (flakes) in specific orientations. It was invented by Armin Elmendorf in California in 1963. ...
. Billets of PSL and LVL are very similar although their sizes are different. Billets of PSL can be as large as wide and long while LVL can range up to wide and long.


See also

* Cross-laminated timber *
Homasote Homasote is a brand name associated with the product generically known as cellulose-based fiber wall board, which is similar in composition to papier-mâché, made from recycled paper that is compressed under high temperature and pressure. Homasot ...
*
Papercrete Papercrete is a building material that consists of re-pulped paper fiber with Portland cement or clay and/or other soil added. First patented in 1928, it was revived during the 1980s. Although perceived as an environmentally friendly material du ...
*
Parallel strand lumber Parallel-strand lumber (PSL) is a form of engineered wood made from parallel wood strands bonded together with adhesive. It is used for beams, headers, columns, and posts, among other uses. The strands in PSL are clipped veneer elements having a ...


References


External links


"Deck Collapse Conclusions"
{{Woodworking Plywood Engineered wood Composite materials