To control the identification and certification of lumber to be used in Canada, exported from Canada, or manufactured in accordance with standards approved in Canada. When lumber is used as a structural material in construction, it has to perform properly. It must be strong enough, stiff enough, dry enough, etc. But how can you tell what performance is needed — and how any particular piece of lumber will perform? In Canada, a sophisticated system of product standards, engineering design guidelines, government regulations, education, review, and checks and balances has evolved over the years to help people determine what lumber they need for a specific building project, and what grade of lumber they are receiving. Since , virtually all of the lumber produced in Canada has been marked with a nationally standardized, easy-to-read Lumber Grade Stamp placed right on the wood itself or by an accompanying certificate, where the final appearance of the wood is of crucial importance.
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The additional expense of kiln-dried wood is the reason it is used in only a small portion of construction. Wood-constructed homes, roof shakes and shingles, exterior decks, and children's play equipment that were built before and not made of cedar or redwood were likely constructed using wood that was pressure-treated with CCA, or chromated copper arsenate.
CCA is comprised of arsenic, chromium and copper. In wood, CCA is used as a chemical preservative. CCA is also a pesticide. The U. EPA Environmental Protection Agency received several petitions in asking that the use of CCA in wood playground equipment and other outdoor structures be banned because of concerns that physical contact with the wood and surrounding soil could increase the risk of certain kinds of cancer caused by the arsenic contained in CCA.
Although an official ban was never imposed, several manufacturers voluntarily discontinued using CCA in their wood products. However, wooden structures and residential components that use CCA pressure-treated wood may still exist in or on a property. Homeowners who are concerned about this can contact their local health department for information on how to have those structures and components tested for arsenic, along with information about their risk of exposure.
Some Final Notes. Get Started. Grow Your Business. Show Menu. Since lumber comes from a natural source, much of it has naturally occurring defects, such as large knots or splits, and these can reduce its strength. Because of these and less obvious defects, lumber that leaves a sawmill must be appraised by trained inspectors and assigned a grading stamp.
Several other agencies are licensed to use these grade rules and apply stamps of their own. But beware that not all grade stamps are legitimate! Inspectors are most likely to encounter 2 structural grade wood in houses.
It can retain a lot of moisture and develop large mold colonies, which are then incorporated into the walls of the home when that lumber is used for framing.
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Lumber Grade Stamps
Because lumber is manufactured from trees which have developed naturally and responsively to their environment and every piece is different it is not possible to anticipate in a grade description all of the possible combinations or types of characteristics which a grader will encounter. These interpretations have been approved by the National Grading Rule Committee and shall be considered a mandatory part of the National Grading Rule. All measurements are based on actual size unless otherwise specified except splits and warp are based on nominal. The limitations on knot sizes and other characteristics governing strength shall not be exceeded. Compression wood shall be limited in effect to other appearance or strength reducing characteristics permitted in the grade. Compression failures and timber breaks are permitted only in the grades of Standard, No. They are limited to the size of the allowable knot hole.