For immediate release --  03/27/1999

Pullman Washington -- When working on any construction project, whether it be home renovation, professional truss building, or other application, it is crucial to the success of the project to use superior quality lumber that you can be confident will last. Machine Stress Rated (MSR) lumber has provided a cost-effective way for builders, contractors and other end users to ensure that they receive top-quality wood. In 1997, more than 1.1 billion board feet of MSR lumber was produced.

"Weak boards cause the majority of problems in lumber applications and the bending stress measurement is the state-of-the-art way to weed out weak lumber," said James D. Logan, President of Metriguard Inc, the world leader in MSR equipment. "A direct physical measurement of lumber’s mechanical properties is more reliable and accurate than estimates based on visual inspection alone."

Logan offered the following ten reasons why building professionals, distributors and other end users should turn to MSR lumber:

1. Higher quality, fewer failures.

MSR production equipment measures every piece in the lumber flow for physical properties, and a sample of five to 10 pieces is tested each shift to verify the results. As a result, lumber that passes the MSR inspection is less likely to fail under its rated stress than visually inspected lumber. End users are assured the boards will meet the specifications associated with the grade stamp. MSR offers superior lumber with less variability in stiffness, allowing for designs that hold to tighter tolerances and guard against expensive failures.

Visually inspecting lumber, on the other hand, is subject to human fallibility and a 5 percent off-grade tolerance is built into the grading rules to allow for this. Boards pass by at 50 to 60 lugs per minute, leaving graders with less than three seconds to evaluate a board. Because of this, it is easy for a human to miss slope-of-grain defects or shake failures that a bending-type testing machine would detect. Many visual characteristics don’t correspond with mechanical properties. Mechanical properties are what make structural products perform.

2. Fewer repairs = Lower costs.

If a piece of lumber fails during or after construction, a suitable repair can be a labor-intensive hassle that wastes wood. Additionally, contractors having to repair a house would not only face the financial losses of the wasted wood but also a significant loss of time—costs which are ultimately passed on to homeowners, but which immediately show up as costs to the builder and the component manufacturer.

The cost of repairing critical components in houses and light commercial construction can be considerable. Truss builders, for example, face repair costs at least ten times higher than if the truss was built with superior wood from the start. An alternative to using MSR lumber is to over-design products in order to provide a margin against possible defects and the associated repair costs. However, in the long term this can be far more expensive and still not as reliable as simply purchasing accurately-graded MSR lumber. By switching to MSR lumber, one major Arizona truss builder was able to eliminate a five-person repair crew, saving them $100,000 per year in salaries, and improving their reputation as a quality producer.

3. Less waste.

Machine stress grading reduces the percentage of lumber that must be discarded at the job site by the component manufacturer. When a shipment of MSR lumber arrives, the builder knows virtually all of it is going to be of a high enough quality to be used. This reduces the board feet that a builder must purchase to finish a job.

"With MSR lumber, truss manufacturers, contractors and builders are able to utilize more of the material they purchase because it has all passed stringent physical standards," Logan noted.

4. Reduce inventory.

Inventory can grow quickly when several lengths of each size and grade of lumber must be kept to fulfill different requirements. Reducing the number of inventory items can be a major cost-reduction benefit for component manufacturers who must handle a variety of grades for different building tasks. If the number of grades can be reduced, larger quantities of each grade may be handled in the same warehouse space.

There are more than 900 sets of design values established for the various grades in all the species and species combinations of softwood lumber. These are replaced by a dozen or so MSR grades which can be applied to any of the species or species combinations to provide a much simpler system. A typical truss plant can cover the full range of grade requirements with three or four MSR grades.

5. Improve capabilities to provide a longer span.

Due to the MSR grades’ improved control of stiffness and strength, truss builders can design and build longer spans into their trusses. This allows for designs that cover larger areas, simplifies the support structure and expands the architectural possibilities.

6. Better performance over lifetime.

There are two concerns for the service life of a board: first, that a board could suffer complete failure and cause the structure to collapse. Fortunately this is rare. The second is the stiffness of a board and thus, the stiffness of the final product. Stiffness in wood is determined by a board’s "E-value," or modulus of elasticity value.

"With MSR lumber, you have better control over the E-value of the wood," Logan said. "Therefore, you have better control over the bounce in floor systems and better reliability in roof structures. This makes for a durable floor surface with a solid feel."

7. Better Load Sharing

Tighter tolerance, that is less variability, in the E-value translates directly into better load sharing between components in a wood structure. Most wood structures are of a redundant nature, with the load forces distributed among multiple components. When one of the components is less stiff (has a lower E-value) than the others, it carries less of the load. This results in more of the load being applied to fewer components which reduces the overall rigidity of the structure and reduces reliability. The assumed Coefficient of Variation (COV) for E in MSR lumber grades is 0.11, compared with 0.25 for visually graded lumber.

8. Better uniformity between suppliers.

Because MSR lumber uses a consistent rating system throughout the industry, an end user can work with multiple suppliers without worrying about compromising lumber quality. An MSR grade is produced to the same quality standard by all the producers. End users can therefore shop for the best price from a number of suppliers.

9. Ability to substitute species.

MSR grades can be produced from a multitude of wood species from a number of different sources. A grade produced from Spruce Pine Fir in Canada can also be produced from a Western or Southern species Lumber design values for MSR grades are more species independent than design values for visual grades. This means that the end user may switch to a less expensive supply without worrying about compromising quality.

10. Savings for distributors.

For a lumber retailer or distributor, stocking MSR lumber can reduce losses. Customers often select lumber based on visual characteristics. The visual grading system for lumber is allowed a 5 percent off-grade rate. Visual inspection of MSR lumber is also allowed a 5 percent off-grade rate, but only after the wood has passed physical testing. Additionally, most MSR lumber is produced with a tighter wane restriction than is required for the grade, because most of the MSR lumber is used in plated trusses which have a low tolerance for wane. If a distributor sells visually graded lumber, he may be left with a pile of rejected stock that simply cannot be sold. With MSR lumber, on the other hand, consumers know they will be getting lumber that will perform physically no matter what it looks like. As a result, more stock is sold, reducing the loss for the retailer or distributor.

Conclusion

"If you are a builder, contractor or other end user who is interested in raising profits and reducing cost while improving quality, MSR lumber can help you reach that goal," Logan added. "By assuring a quality level unmatched by other lumber grading systems, MSR lumber can reduce waste, virtually eliminate lumber-related repairs and provide unsurpassed confidence in your end product."

For more information on MSR lumber, contact Metriguard Inc, at PO Box 399, Pullman, WA 99163, or call (509) 332-7526; or fax (509) 332-0485; e-mail sales@metriguard.com; or visit on the web at www.metriguard.com.