Harvest the Wood
One of the benefits of oriented strand board (OSB) is that it uses small-diameter logs from a fast-growing species chosen for its mill and plant geography, such as Aspen, Southern yellow pine, poplar, or black poplar. Look for manufacturers that work with forests that are managed responsibly (such as FSC- or SFI-certified land) and gather raw materials from a close radius (say, 50 to 150 miles). Once the logs are on site, they are stacked or, in northern areas during colder months, placed in large ponds that are heated by wood burners powered by the mill’s scrap wood. These ponds unfreeze, wash, and soften the logs.
Break it Down Now
The logs are debarked—bark is often reused as fuel for plant operations—and fed into stranders, where knives in either ring or fan configurations (with perhaps 30 to 50 blades per strander) slice and dice the entire log into strands that are generally 3 to 6 inches long, 1 inch wide, and 0.03 inch thick. No wood is wasted here: Strands are screened to weed out the undesirable, which are fed into wet fuel bins for reuse. Doing this before drying the strands eliminates excess energy use, and OSB plants usually keep a reserve of strands on hand in case a strander goes down for a knife change, so that the line can run continuously.
Strand Together Under Pressure
After tumbling through a dryer where temperatures may range from 1,500 F at the inlet to 200 F at the outlet, the strands are blended with a concoction of resins and waxes that varies by manufacturer, wood mix, time of year, and other factors. Strands are then layered into 3- to 8-inch-deep mats on a continuous belt that is roughly 8- to 12-feet wide, and the length of these mats are cut to fit a plant’s presses. Environmental controls should clean exhaust air, and wet electrostatic precipitators, high heat, and beds of media may filter out any ash or VOCs before discharge. Then it’s time to press: Mats are baked above 400 F and under pressure—which varies by board thickness, but is generally around 1,300 psi.
Cool It, Cut It, Deliver It
Coming out of the presses (whose exhaust air is often treated by regenerative catalytic oxidizers or regenerative thermal oxidizers before it is released), the OSB boards are cut to size, with most panels trimmed to 4 feet by 8 feet, and scrap edges and dust reused as fuel sources for the line. Boards may receive modifications such as a radiant barrier or tongue-and-groove cuts. After quality control checks, the boards are then bundled for delivery. Scroll below for a selection of OSB products on the market.
Ainsworth, pointSIX Flooring
Featuring a patented tapered-edge that reduces swell, pointSIX OSB flooring from Ainsworth should not warp, sag or cup. It features tongue-and-groove profiling to lay flat, and the taper of its edge was based on research indicating that a 0.6mm tape depth is the most effective in reducing edge swell. It comes with a 25-year delamination warranty, and is available in a range of standard sixes and thicknesses. Wood is culled from SFI-compliant forests in Alberta, British Columbia, and Ontario, Canada, with the majority of it being northern aspen and a small portion in British Columbia being pine timber killed by the mountain pine beetle. ainsworthengineered.com
LP Building Products, LP TechShield Radiant Barrier
LP Building Products sources small, fast-growing trees from SFI-certified forests and low-emitting resins for its TechShield Radiant Barrier Sheathing. The company uses the entire log in the manufacturing process, with any waste being repurposed or used as fuel for the mill. These OSB panels feature a thin sheet of aluminum laminated to LP OSB sheathing and include VaporVents, incisions that penetrate the radiant barrier, glue, and OSB substrate to allow the panels to dry quickly from construction moisture. Panels measure 47 7/8” by 95 7/8” can come in the following performance categories: 7/16, 15/32, ½, 19/32, and 23/32. LP reports that it only uses low-emitting, safe resins, and does not add urea formaldehyde in the process. lpcorp.com/techshield
Edge Gold Flooring, Weyerhaeuser
Now featuring Down Pore self-draining technology, Weyerhaeuser’s Edge Gold OSB flooring panels are designed to channel water from the panel surfaces and drain it off the joists below to further enhance the panels’ resistance to rain and moisture. The Down Pore technology consists of three shaped drainage grooves on one of the narrow ends of each 4’ by 8’ panel. The deisgn should not clog from sawdust or adhesive, according to the manufacturer. Weyerhaeuser has laos enhanced the Edge Gold edge seal formulation to reduces edge sweel and extended the company’s “no sand” guarantee from 90 days to 200 days. This guarantee assures builders that the panels will resist edge swell for more than six months of weather exposure during construction. Weyerhaeuser also provides a 50-year limited warranty. woodbywy.com
ZIP System Liquid Flash, Huber Engineered Woods
ZIP System Liquid Flash is true to its name: a liquid-applied flashing membrane to seal irregular, curved, or hard-to-flash areas. It is meant to complement Huber’s ZIP system tape and roof and wall sheathing panels. Available in a 20-oz. sausage tube or a 29-oz. cartridge, ZIP System liquid flash bonds and cures in wet weather and on damp substrates and becomes waterproof shortly after installation, according to the manufacturer. The ZIP System roof and wall sheathing consists of structural OSB panels with built-in protective barriers. The sheathing is now available with continuous foam insulation as well. zipsystem.com