The Proprietor Review

blue stain bug kill

This picture of some lumber going out to market is an export grade and the blue stain is indicative of bug kill. It does not affect the quality of the wood. Number 3 grade is utility grade used in manufacturing, for boxes etc. these 18 foot 2x4s are utility or #3 grade and for export. the picture was taken on a truck on Nicola Ave Merritt last month.

The Lumber Grade Stamp
A grade stamp shows: (1) the registered symbol of the certified agency; (2) the mill identification number; (3) the species or species group; (4) the seasoned condition; and, (5) the grade name or number.

Individual pieces of lumber show a wide range in quality and appearance with respect to knots, slope of grain, shakes and other natural characteristics. Therefore, they vary considerably in strength, utility and value.

Canada has grading rules that support a standard among mills manufacturing similar woods to assure customers of uniform quality. Grades standardize the quality of lumber at different levels and are based on moisture content, size and manufacture at the time of grading, shipping and unloading by the buyer.

The National Lumber Grades Authority (NLGA) is responsible for writing, interpreting and maintaining Canadian lumber grading rules and standards. The Canadian Lumber Standards Accreditation Board (CLSAB) monitors  quality in Canada’s lumber grading and identification system.

Treated Wood Products

Wood is sometimes treated with preservatives that improve service life under severe conditions without altering its basic characteristics. It can also be pressure-impregnated with fire-retardant chemicals that improve its performance in a fire.

Kiln Drying

The moisture content of freshly sawn timber is higher than it is under normal service conditions so it is generally dried before being shipped to users. Many British Columbia wood species are seasoned easily and uniformly through kiln drying. This increases the wood’s structural performance, reduces swelling and shrinkage, and enhances its appearance and workability. Virtually all lumber is kiln dried to a moisture content of 19 per cent or less.

Machine Stress Rating

Machine stress-rated and machine-evaluated lumber is readily available for end-uses where high strength is critical, such as truss rafters, laminating stock, I-beams and web joints. Machine grading measures a characteristic such as stiffness or density that correlates with the structural properties of interest, such as bending strength. The result is a more precise understanding of the strength of each piece of lumber than is possible with visually graded lumber, which allows designers to use full-design strength and avoid overbuilding.

Note: secondary manufactures will try to recover individual pieces of 10r 2 grade lumber from the utility slings they buy.