Forest Harvesting, Wood Utilization, and Products of the Future

H. M. Montrey, deputy director, Forest Products Laboratory, and John I. Zerbe, manager, Energy from Wood Program, Forest Products Laboratory, Forest Service, Madison, WI.

In the United States, wood is still a major construction and industrial material. Wood housing has been the mainstay of the American family from the time of the first European settlers, and it remains important to our way of life. Today most of our housing is predominantly wood framed. Even single-family houses and low-rise apartment buildings with masonry walls often have wood framing behind the masonry veneer and framing in floors, partitions, and roofs. Results of today's research in improving the use of wood from foundation to rooftop will ensure an adequate supply of comfortable housing at a reasonable cost of construction in the future.

The United States is fortunate that it also has adequate wood supplies. Improvements in harvesting methods and forest-management practices are helping hold costs of timber to affordable levels. Production of this versatile, renewable, and abundant material now exceeds harvest, and available supply is increasing by 1 Percent a year. Today much of the excess is in lower grade hardwoods (broad-leaved trees), but research also is leading to ways of making these trees attractive for use in products of tomorrow. More efficient use also is contributing to an effective extension of timber supplies.

Spaceboard a molded structural sandwich product made from paper will be used for a variety of applications, including wall and ceiling panels and decking.

Future research will be focused on more closely matching product end-use requirements with raw material quality and processing technology. In 1952, only 60 percent of the residues generated at forest-products manufacturing plants were used for other purposes, but in 1976 all but 4 percent of timber brought to the mill was used. Nearly 60 percent of processing residues were used for pulp and about 20 percent for fuel. The remainder was exported or used in particleboard and a variety of other products.

In the future, more of the residues are expected to go into composite panel products that may be used in structural applications which previously required boards or plywood. Research over the past decade has accelerated the manufacture of non-veneered structural panels such as oriented strandboard and waferboard. As for other particleboard and fiberboard products, manufacturing of these nonveneered structural panels does not require large or straight-growing trees. Composite panel also can be made from a large variety of species, including hardwoods, which are often produced in excess.

Growth and use of forest products may be managed to enhance the environment through resisting erosion by water and damage by wind. Well-managed forests also may help in soil conservation by maintaining a desirable soil nutrient balance. Harvest revenues may pay for better forestry practices as well as other forest uses such as recreation. Research and development efforts can lead to improved harvesting methods, higher levels of forest land management, and increased benefits.

Just as housing construction has been based on wood, U.S. industry has long depended on wood as an important raw material. In 1972 the National. Commission on Materials Policy found that, of the 21 tons of material per capita required annually in industrial operations, 9 tons were for fossil fuels, 2/3 ton for metals, and 1 1/3 tons for forest products. Comparing dollar values for these materials is difficult, but the value of primary forest products is clearly comparable to that of metal products.

Besides its obvious uses in industrial and consumer products, wood has several intriguing applications in national security and emergency preparedness. Wood is not comparable to metals in importance for armaments and ammunition, but it can replace scarce metals in other applications and has some unique uses for which metals cannot compete. Last year marked the first time since World War II that the Department of Defense awarded a contract for minesweepers, and these ships will be made entirely of wood. Successful large wind electrical generators, which have been designed since the energy crises of 1973 and 1979, generally use blades made of wood.

The Truss-Framed System uses less lumber and requires fewer supports than conventional framing.

Wood Use in Housing

One of the most innovative uses of wood in housing construction and one likely to grow significantly in the future is wood foundations. Historically, builders have contended that durable foundations have to be built of masonry. But research has shown that suitably treated wood and plywood foundations with proper drainage of water away from the foundation wall can provide some economic, structural, and esthetic design advantages. Wood foundations should prove to be particularly beneficial in colder climates where they may be erected during most of the year and easily fitted with insulation.

Wood Floor Framing. Wood floor framing has been improved recently with the acceptance of a construction method in which floor surfacing, such as plywood, is glued to load-carrying floor joists to provide composite structural action. The result is more stiffness and strength with less material. Increased use is being made of parallel chord trusses and I-beams, particularly for long spans, as availability of wide lumber decreases. In the future, floor joists may be molded into structural shapes, such as I-beams, from available particulate material as is used in the manufacture of oriented strandboard. Already, the first plant is being built to construct framing members with an inner core weaker material and an outer web of stronger material. The plant will manufacture Com-Ply , which forms a rectangular cross section like conventional lumber studs and joists but has a particleboard core and veneer surface layers.

Wall Framing. Future wall framing for houses will likely see more applications of composites and other improved structural shapes that may be fabricated from more abundant lower-value materials such as strands from hardwoods. A new product type from pulp fiber being studied at the Forest Products Laboratory shows promise for building modules as well as improved paperboard containers. This product Spaceboard is a molded structural sandwich that has superior strength-to-weight characteristics and is not as limited in orientation to load application as conventional framing materials. Engineered paperboard structures could become a reality and make better use of our wood resources if adverse effects of moisture and humidity can be overcome.

Oriented strandboard is a new product that fulfills a need for a composite panel board with mechanical Properties equivalent to those of structural plywood. Oriented strand-board is composed of three layers of aligned strands bonded together with a liquid phenolic resin. The wood strands in the top and bottom layer lay parallel to panel direction; those in the core lay perpendicular to the panel direction.

In 1980, there was only one structural flakeboard plant in the United States. Today, there are over 15, and construction of other facilities has been announced. Future research will lead to molded oriented strand products tailored for specific end-use application.