Wood – The Perfect Building Material
Investigating the Role of Wood in Building and Construction
Sep 4, 2009
Although metals, concrete, and plastics have replaced many of its traditional uses, the strength, insulating properties, versatility, ease of handling, and natural beauty of wood still make it the building material of choice.
The United States and Canada are the leading lumber-producing countries in the world. About half of the wood harvested in the United States is used as lumber, primarily for construction, with a considerable amount used to make furniture.
Categories of Lumber
Two basic categories of lumber are recognized: hardwoods and softwoods. The term hardwood refers to trees in the angiosperm group (dicots) while softwood refers to trees in the gymnosperm group (conifers).
The degree of hardness indicates the sturdiness of the cell walls and the amount of lignin they contain. The harder the wood, the more resistant it is to wear and decay.
Hardwoods
Some hardwoods are so dense that it is difficult to actually drive a nail into the wood. While such wood is less than desirable for construction purposes, it does illustrate that such types of wood are aptly named.
The oaks are the most economically important group of hardwood trees in the United States. Oak wood is very heavy, durable, and attractive when finished. It is widely used in general construction and for making furniture, flooring, trim, cabinets, posts, and railroad ties.
Other hardwood trees of value are black walnut, hickories, maples, sweetgums, tulip trees, and the birches. American chestnut was also a widely used hardwood of times past but was wiped out when chestnut blight was introduced to North America.
Softwoods
It is estimated that around 35% of the world’s forest area is dominated by softwood species, and in North America, they cover far more area than hardwood forests.
The greatest use of softwood lumber is for the framing and structural components used in home construction. Softwoods are also the major constituents in the production of plywood. Plywood consists of three or more thin sheets of wood glued together at alternating right angles to each other. This layering produces a sheet or board that is lightweight but stronger than a comparable piece of solid wood. Plywood is used for roofing and wall sheeting, subflooring, shelves, cabinets, boxes, and signs.
The most valuable softwood is undoubtedly pine. There are 35 species of pine trees native to North America with longleaf, loblolly, and yellow pine being the major sources of lumber in the south while ponderosa pine fills this role in the west.
Douglas fir is another of the most desirable softwood trees in the world. This strong wood is used in the production of plywood, and is a major source of large beams. Douglas fir grows throughout the Rocky Mountain region but reaches it greatest development in the Pacific Northwest, where the species rivals the redwoods in size and grandeur.
A Precious Resource That Must be Protected
Around one-third of the earth’s land surface is covered by the forests that supply the wood and wood products used by humanity. Sadly, the world’s forest are being cut down and destroyed at an alarming rate. Forest destruction is not new. It has been going on since humans harnessed fire and developed the tools to fell trees. However, it continues to get worse. Forestry experts estimate that 30%-50% of the world’s forests have already been destroyed.
While some reforestation programs are in place, many ecologists believe that new forestry management practices must be implemented if forests are to remain as complex ecosystems. Only about 13% of the world’s forestland is being managed, and only about 2% of the world’s forests are protected in forest preserves. As the world population continues to grow, so does the demand for forest products. Everyone has a responsibility to protect and maintain this valuable resource and natural wonder.
Whatever the form – lumber or plywood – wood has been and continues to be the most useful construction material on the planet.
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