Publication Date:
Thu, 2001-05-31 19:00
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Southern Pine is a general group of four principal tree species: long-leaf, shortleaf, slash, and loblolly. Collectively, this species group ranks among the strongest, most versatile woods for structural applications.
When most wood is exposed to the elements, excessive moisture, or contact with the ground, it will decompose. That is because four conditions are required for decay and insect attack to occur: moisture, a favorable temperature (approximately 50 to 90 degrees Fahrenheit), is removed, infestation and decomposition will not occur. Chemical preservatives eliminate wood fiber as a food source.
Why design and build with pressure-treated wood? Figure 1 indicates, by region, the level of wood deterioration throughout the United Stats. As shown, deterioration zones ranging from moderate to severe cover most of the country.
Modern science has developed preservative treatments that are odorless and colorless, and leave the wood paintable and dry to the touch. Treatment with chemical preservatives protects wood that is exposed to the elements, is in contact with the ground, or is used in areas of high humidity.
Southern Pine has long been a preferred species when pressure treatment with preservatives is required, because of its ease of treatability. The unique cellular structure of Southern Pine permits deep, uniform penetration of preservative chemicals, rendering the wood useless as a food source for fungi, termites and micro-organisms. Some 85% of all pressure-treated wood is Southern Pine.
However, be aware that all treated wood is not created equal. Most wood species do not readily accept chemical preservatives, and must first be "incised" or perforated with a series of small slits along the grain of the wood's surface. Incising allows sufficient penetration of the preservative to meet American Wood Preserver's Association (AWPA) [1] Standards. Southern Pine is one of the few wood species that does no require incising.
In addition, the use of treated Southern Pine products poses no measurable risk to humans, animals, plant or marine life.
Scientific research studies have shown the following:
- Preservatively treated wood products last longer than alternative materials, conserving a renewable, natural resource.
- Wood preservatives do not aggressively leach into the ground or waterways, drinking water supplies, or adversely affect marine life.
- Proper handling and use of treated wood poses no increased risk of cancer or other illnesses among human, animal, and marine life.
- Preservatively treated wood products have been extensively tested and proven to be more reliable and durable than alternative products which require more energy to produce, and may also be aesthetically unacceptable to consumers.
How long does pressure-treated wood last? Currently available research shows that wood that has been properly treated and installed for its intended use can be expected to last for many decades.
Ongoing tests sponsored and monitored by the USDA forest Service's Forest Products Laboratory confirm this finding. Test stakes of treated wood have been buried in the ground at various locations, stretching from the Mississippi Delta to the Canadian border. Data analysis indicated that CCA-treated Southern Pine stakes in place since 1938 have shown no failures at chemical retention levels of 0.29 pounds of preservative per cubic foot of wood, or higher.1
Footnotes:
(1) "Comparison of Wood Preservatives in Stake Tests - 1995 Progress Report", Forest Products Laboratory; Research Note FPL-RN-02; U.S. Department of Agriculture
