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Stretching our timber resources.

The saying "They don't build in 'em like they used to" is particularly true of today's new housing. a major reason: timber products are changing. The change starts with the trees themselves.

The vast timberlands of the West, logged for over a century, are becoming more and more second growth. Increasingly, trees now being cut are smaller-diameter specimens grown in managed forecasts. And costs have climbed, forcing the lumber industry to use wood fiber more efficiently.

In housing, new wood products and lumber-efficient design are the result. This shows in the quantity of lumber going into a new house: In 1950, it averged about 10,800 board feet. Today, the average house is almost twice as large (about 1,700 square feet), but it uses nearly the same amount--about 11,200 board feet.

Look at beams an trusses. Since there aren't many large-diameter trees left to make into big beams, glue-laminated ones--made of lumber glued together under pressure--have been developed. Similar in function are lightweight woven I-beams, which have a slender center section of plywood and outer edges of narrow, laminated veneers. "Each tree goes 2-1/2 times further as an I-beam than as a 2 by 10," says one spokesman. And today's ready-made wood roof trusses, employed in about 95 percent of new housing, use small-dimension wood (2 by 4's or 2 by 6's) joined with metal plates to create an engineered roof support.

This truss technology is extending to floor trusses and even to truss-framed houses, in which roof, floor, and wall sections are connected into modules that arrive at the building site stacked on a truck.

To get the most out of each tree, builders are now using wha was once discarded. "Finger-jointed" wood trim, for example, is machined from glued-together scraps of lumber.

One of the biggest wood-savers has been the use of panel products for sheathing. Plywood and hardboard were the first, but some new products are now on the scene. Composite panels have particle-board cores bonded between conventional face and back plies. Nonveneered panels are of three sorts: structural particle board, waferboard, and oriented strand board. The last two are significant because they can be made of large flakes of aspen, a tree previously ignored by the lumber industry. These new panels use about 90 percent of a log, compared to about 50 percent for lumber. They can often substitute for plywood. (You'll be seeing more on panel products in a future issue of Sunsent.)

A new building technology that uses pressure-treated lumber and plywood in foundations is providing significant savings in cost of materials and labor. The foundations can be prefabricated and erected by ordinary carpentry crews, even in cold or wet weather.

More efficient use of tree fiber is one way to keep housing costs manageable. It's also a way to stretch the West's valuable timber resources further than ever before.
COPYRIGHT 1984 Sunset Publishing Corp.
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Copyright 1984 Gale, Cengage Learning. All rights reserved.

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Publication:Sunset
Date:Apr 1, 1984
Words:479
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