The new lumber - lumberyard technologies produce stronger lumber

Sunset, Nov, 1995 by Bill Crosby

One of these beams is traditional 2-by-10 Douglas fir. The other, "engineered" from strands of different wood, is measurably stronger. What's going on at the lumberyard and why?

Walk through a lumberyard or drive through an emerging housing development, and the view might confound you. Where's the good-looking wood? What are those weird-looking I-beams holding up the floor? What's that flaky-looking stuff on the roof where the plywood should be?

Everything you see is related to one basic fact: we're not cutting down as many big trees to get our wood. You can still find all the old, big-tree products - at prices that reflect their decreasing availability. But taking up the slack are homely lumber from smaller trees, engineered products that substitute for big lumber, and other wood-based materials that use every last bit of the tree, including scrap that would otherwise go to the dump.

Some of the new products aren't pretty, but they're as strong as or stronger than traditional sawn lumber, and they're also incredibly resource efficient. If there's one overarching change in the use of trees as building materials, it's that wood - from standing old-growth trees to scrap wood - is too valuable to waste.

YOUNG TREES: BABY BROTHER IS NOT THE SAME

Most Western forests open to harvest have been cut at least once, and the second- and third-growth timber being cut and put to use for framing, decking, fencing, and the like is 50 to 80 years old versus several hundred for first-growth wood. These young trees have a higher percentage of juvenile wood, the fast-growing early growth that is less dimensionally stable, says Robert Leichti, associate professor at Oregon State University's Forest Research Laboratory.

"It stays straight as long as it's wet, but as it dries it tends to shrink and swell," Leichti says. Frame a house with it and that wood will move around a bit as it dries, or, to use lumbermen's terminology, it'll take a walk on you.

Although you can eliminate most of the warping problems with young wood by buying wood that's air- or kiln-dried, nearly half the houses built today are framed with green wood, generally because it's cheaper and easier to nail. Many new houses have textured walls to hide the imperfections caused in part by studs deflecting as they dry.

Lumber from small-diameter trees also tends to have more defects like knots, pitch pockets, checks, and particularly wane (bark or a missing edge marking the curved outer dimension of the log). Although lumber grades based on visual and strength characteristics have not changed, you'll likely now find few boards above grade in a given batch. Studs in the past might have been better-looking, but they were no stronger.

Another development related to small-diameter trees is 5/4 decking, a lumber dimension that's gaining popularity. This 1 l/4-inch-thick material uses 1/4 inch less wood than, say, a 1 1/2-inch-thick 2-by-6, letting more lumber come out of each log.

As old-growth lumber has gotten scarcer, we're also seeing increased use of woods such as fir, pine, and hemlock that have been pressure-treated with preservative to give them the same decay-resistant properties as redwood and cedar heart-wood (the red wood from the center of the tree). Often this lumber has a little creative staining along with the preservative: the sign over the stacks of redwood at your home center might reveal you're looking at two words, not one.

Such wood products, increasingly made from young trees, are particularly appropriate where strength is needed and appearance isn't an issue: your true redwood deck can sit on pressure-treated underpinnings.

ENGINEERED WOOD: MAKING BEAMS INSTEAD OF GROWING THEM

Wood-frame construction used to be based on big trees, from which you got big boards for posts, beams, joists, and the like. As early as the 1930s, small-dimension boards were stacked and glued together to make laminated beams as a replacement for larger solid-sawn wood. In the '50s, mills started creating lumber by gluing together end to end scrap wood devoid of structural flaws like large knots. Today, even smaller pieces of wood - most no more than 1/10 inch thick - are being made into products that perform as well as or better than most dimension lumber.

These products take a low-grade material - often smaller trees or species like aspen considered junk by traditional logging standards - and turn them into a high-grade material. Five new types of engineered wood are shown in the illustration on pages 74 and 75. Price comparisons are approximate, because wood prices vary by region and season.

The I-joist is the engineered wood product that's being most aggressively marketed against dimension lumber. Besides using half the wood of similar-size sawn lumber, the product is absolutely consistent. "It's not that it's stronger or weaker; it's that every board performs the same," says Garry Lee, plant manager for Trus Joist MacMillan's wood I-joist plant in Eugene, Oregon.

WAYLAYING WOOD ON ITS WAY TO THE DUMP