Engineered Wood for Efficient Load Support
In the past, structural elements of a structure were reinforced by adding mass. The larger the distance that a beam had to span, the wider and taller it got. There is a limit, however, to how large a timber can be, which effectively limits how large a room can be without the need for added posts and other structural supports. Today, engineered lumber makes it possible to span vast distances without added supports and without added cost. It’s truly an amazing building material of the future.
Engineered Wood Options
Laminated-veneer lumbers (LVL), parallel-strand lumber (PSL), and I-joists are the engineered wood options most commonly used in structural applications. Each has specific strengths and thus specific applications.
LVL is made by gluing together multiple thin strips of wood under heat and high pressure. Poplar, pine, and fir are the most commonly used woods for producing LVL. By alternating the grain patterns of each layer of LVL, it is possible to produce a product that is substantially stronger than a similarly sized piece of solid (i.e. non-laminated) timber. LVL comes in thicknesses of up to three and one-half inches and lengths as great as sixty feet. It is commonly used for door and window headers, ridge beams, cantilevered roof supports, and stair stringers.
PSL is similar to LVL in some ways, but very different in others. By using smaller pieces of lumber, PSL can be laminated in two directions, rather than just one direction as with LVL. This process helps to evenly distribute knots and other defects common in wood products, which increases the strength of PSL over LVL and any other wood product. The manufacturing method also allows for beams of any length to be produced, making PSL manufacturing more flexible and cost effective. PSL is used for all of the same things LVL is used for, but can span greater distances without support.
I-joists are made with a vertical piece of oriented strand board sandwiched between two horizontal pieces of standard lumber or LVL both above and below. This makes I-joists lighter than solid wood joists, but also stronger. I-joists can span greater distances than solid joists and holes can be drilled into them without compromising their strength.
Engineered Wood Brands
There are only a handful of companies that make LVL and just one company that make PSL. I-joists are easy to manufacture and thus multiple companies produce them. That said, not all I-joists are equivalent. Learn More About Engineered Wood Choices Here
Weyerhauser patented the process for making PSL and thus is the only company producing this product, which it calls Parallam®. Parallam® comes in three configurations: beams, columns, and plus. Plus is for exterior use.
Parallam comes in multiple depths and has a maximum span of sixty feet in most applications. Different versions of Parallam® are used for horizontal versus vertical spans. There is also an exterior offering that can be installed directly into the ground or withstand saltwater splash. Parallam® is covered by a 30-year warranty.
Weyerhauser Microllam® LVL is the affordable engineered lumber solution for settings in which the strength of Parallam® is not required. Microllam® is engineered in header, column, and beam options.
Weyerhauser TJI joists have been the most-used engineered wood product for 14 years running. They are valued for their strength, light weight, and low cost. TJI joists are easy to customize and come in a fire-rated option for enhanced home and structure stability. They are available in depths of eighteen to twenty four inches.