Advances in timber technology mean more options for architects and designers seeking sturdy materials for structural applications. Engineered wood products run the gamut from oriented strand board to plywood to laminated veneer lumber (LVL) and can be a resilient alternative to solid-sawn wood while increasing a project’s design potential. The products have become such an integral part of residential and light commercial construction that we wanted a look behind the scenes of their manufacture. In early November, we visited engineered-wood-products manufacturer Weyerhaeuser’s veneer technology plant in Buckhannon, W. Va., where two of the company’s offerings—Microllam, a LVL, and Parallam, a parallel strand lumber (PSL)—are made in tandem to reduce material waste. Watch the video above or read the photo essay below to follow the process.


Credit: Lauren Honesty


In 2012, Weyerhaeuser harvested approximately 205,112 acres of North American timberlands from its 20.8-million-acre stock of Sustainable Forestry Initiative-certified timberlands as well as from private land. The company doesn’t own any land in West Virginia, so the Buckhannon mill gets its materials through agreements with 200 to 250 loggers within a 120-mile radius who work on private land, and by way of landowners who cut their own timber and drop it off at the mill where they’re paid by the ton. On the day we visited Weyerhaeuser’s Buckhannon plant, the company’s foresters took us to a 60-acre site in Barbour County, W. Va. There, the company had purchased the trees from a private landowner to be logged and processed during a two-year period. The site yields a variety of wood species—including yellow poplar, black cherry, and red and white oak. After the company harvests the timber, the landowner will allow the forest to regenerate naturally over a 30- to 40-year period, during which time the property will be preserved from other development. 



Credit: Hallie Busta


Two blue lines—one at about eye-level on the trunk and another closer to its base—indicate that the tree was part of the purchase agreement and that it can be harvested. 



Credit: Hallie Busta


A machine called a feller buncher cuts trees at their stump and removes their limbs and tops. The logs are left on logging roads carved into the hillside for collection by another piece of equipment, a grapple skidder. The grapple skidder drags a handful of logs to the site’s landing area, where the loader operator sports them by species, checks for defects that would slow the manufacturing process or render the wood unusable, and cuts them to size for transport. 



Credit: Lauren Honesty


The logs are taken by truck from the landing to the log yard, where they are stored in rows based on size and weight in preparation for processing. 



Credit: Lauren Honesty


The logs receive a 12-hour-long hot water bath that softens their bark for easy removal. A rotary veneer lathe, which uses a 105-point laser scanner to pinpoint each log’s center, peels them like a Swiss roll into 1/8-inch-thick sheets at a rate of 1,200-feet-per-minute. For perspective: a 24-inch-diameter log takes about 5 seconds to peel. The veneer ribbon is evaluated for its moisture content and visual quality and is automatically cut into pieces that will be used for either LVL or PSL products. Pieces with inconsistencies such as knots, bark, wane, and voids—usually found at the beginning and end of each log’s veneer sheet—are used for PSL. The high-grade sheets are cut to 4-foot-wide-by-8-foot-long dimensions and used in LVL production. The lathe processes approximately 3,500 logs each day. 



Credit: Hallie Busta


The sheets are dried in groups based on type—LVL or PSL—and moisture content. Inside the dryer, where internal temperatures reach 400 F, a conveyor belt made from perforated screens transports the material through the five-minute process. LVL accounts for approximately 60 percent of the plant’s production, while PSL claims the remaining 40 percent. Once the sheets are dried, they are sorted by strength, visual grade, and moisture content. The LVL and PSL sheets are stored in separate piles in the warehouse until processing. 



Credit: Hallie Busta


The top of each LVL ply is coated with a phenol-formaldehyde adhesive. The glue will hold together the 12 to 15 plys that comprise each 1 3/4-inch LVL beam. The plys are stacked and run through one of two 110-foot long presses that each process 6,000 cubic feet every 24 hours. An impregnated wax paper is pressed into the beam’s outer faces to improve its moisture resilience. 



Credit: Hallie Busta


The LVL machine at the Buckhannon plant turns out product in long spans that are cut to sizes specified by individual orders. The plant can fabricate beams up to 80 feet in length but averages 58-foot lengths due to market demand and storage capacity. 



Credit: Hallie Busta


The dried PSL pieces are fed onto a series of conveyor belts that detect each one’s weight before cutting them into 1-inch-wide strands. The strands are coated with an adhesive and distributed evenly into a trough that serves as a mold for the PSL billet. 



Credit: Hallie Busta


Once the trough is full, the material is fed into a microwave press that consolidates the strands and cures the adhesive bond. The Buckhannon plant makes PSL billets in 12-inch to 20-inch heights. 



Credit: Lauren Honesty


The LVL and PSL products sit on racks in the warehouse for a period of eight to 12 hours while they undergo additional quality assurance checks in an on-site lab to determine stiffness and shear and tensile strength values. Then, they are cut to size, sealed with a proprietary sealant that resists moisture during transportation and installation, and wrapped for sale through the company’s distributor partners. Product manufactured in Buckhannon is sold in geographic markets east of the Mississippi River in Canada and the U.S.

Video by Lauren Honesty.