When was pressure treated lumber invented

CCA also helps keep the wood clean and safe to handle when used as recommended. In the Wolmanizing treatment process, the pentavalent arsenate becomes fixed, or chemically bound, in the wood cells as highly leach-resistant insoluble precipitates. Lumber, timbers or plywood is loaded onto tram cars. The trams are moved into a large, horizontal treating cylinder.

The cylinder door is sealed, and a vacuum is applied to remove air from the cylinder and the wood cells. CCA preservative is then pumped into the cylinder and subjected to pressure sufficient to force CCA into the wood, where it impregnates the wood at the cellular level. Total treating time varies depending on the species of wood and the amount of preservative required.

The wood is then moved to a concrete drying pad until the wood is dry enough to handle safely. It is protected with a copper-based preservative copper azole containing an organic fungicide. Host Commentator Charlie Nardozzi shares his information on remedies and alternatives to pressure-treated wood. It revolutionized outdoor building projects by giving consumers a new treatment for wood that, like creosote, protected it from rot for 30 years. The most commonly used pressure-treated wood is chromate copper arsenate, or CCA.

But not for long. The EPA and the wood preservative industry have agreed this past winter to ban the sale and use of CCA-treated wood by the end of next year. The concern is the arsenate, a chemical form of arsenic and a well-known poison. CCA-wood is pressure-treated with arsenate to kill any rot-causing organisms. Independent studies claim otherwise. Many of these applications are still used in practice today. Pressure-treating with preservatives Wood exposed to the elements eventually falls prey to insects or fungal organisms that cause decay through a natural process.

For this reason, it is important to protect wood and make it less desirable to decay organisms. This is done through the process of pressure-treating wood with preservatives.

To facilitate the production of pressure-treated wood products, the preservatives are manufactured using either oil or water as solvents to assist with penetration into the wood. Oilborne preservatives Oilborne preservatives include creosote—a byproduct of the coking process in steel production first introduced in the early s.

Another oilborne preservative, pentachlorophenol PCP , was introduced in Canada in the s and is primarily used for utility poles and cross-arms but can be specified to treat timber for construction. The oily nature of these preservatives helps stabilize the wood and protects it from moisture and wood-destroying organisms.

It was introduced to the residential construction market in the s to provide an alternative to more costly naturally durable wood species. As a competitively priced alternative with similar service life, CCA pressure-treated wood products in Canada allow for the use of more plentiful Canadian species such as spruce, pine, and fir.

Thedo-it-yourself market requires products that are simple to work with and easy to install. It was CCA that initially assisted in the popularity of pressure-treated wood in outdoor residential applications and grew the market for future generations of treated wood products. Permanent wood foundations using CCA pressure-treated wood were also introduced in the s as an alternative to concrete and block foundations.

Wood foundations provide for easy construction, especially in areas where other foundation materials are difficult to obtain or construct. They provide a warm, dry, and easy-to-finish basement or crawl space. The National Building Code of Canada NBC and various provincial codes include permanent wood foundations as a standard form of residential foundation.

Currently, CCA is primarily used in industrial, commercial, and agricultural applications.