What’s in A Grade?

Words: Jared KennisonOne of the most durable and cost-effective choices for scaffold plank by mason contractors is solid sawn scaffold plank. The two main choices these days are MSR (Machine Stress Rated) and DI 65 (Dense Industrial 65), both made from Southern yellow pine species, manufactured mostly in the Southern United States. Before the very first load of “Scaffold Grade” plank was made in 1972, mason contractors and other trades used solid lumber boards of whatever species they could find. In that year, SPIB (the Southern Pine Inspection Bureau), which is one of the third-party inspection agencies, created a higher grade, which is the Scaffold Grade that we know today.

The DI 65 Scaffold Grade was intended to satisfy safety requirements for scaffold plank set by OSHA/ANSI. As with other graded lumber products, each plank or batch is visually inspected by a certified lumber grader for characteristics and defects before it can be stamped as scaffold plank. Characteristics like knot size, splits, breaks, slope of grain, growth rings, etc., all have allowable specs within the grade rule.

Technological advancements have allowed mills to use a more efficient process in which to pull Scaffold Grade. MSR, or Machine Stress Rated Scaffold Plank, is produced by mills visually inspecting boards to be run through the MSR machine, which can qualify each plank for density and other characteristics defined by the SPIB grade rule. This process is also known as non-destructive proof testing, which results in more consistent flatwise bending strength in each piece compared to only visual grading for DI 65 scaffold plank. Both MSR and DI 65 are interchangeable and can be used as scaffold plank.

Visually speaking, both products appear the same. Both have a mill/grade stamp that certifies that they meet OSHA/ANSI requirements for scaffold plank. They are both rodded, clipped and embossed on the edge with the customer’s name and the words “MEETS OSHA STANDARDS.”

MSR scaffold plank takes the grade a step further with its advanced qualification and improved efficiency of pulling a higher grade. Readers should note the published letter from Bob Browder, director of the Lumber Division of Southern Pine Inspection Bureau, regarding machine and visually graded scaffold plank.

You should ask the following questions regarding suppliers and manufacturers of DI 65 or MSR solid sawn scaffold plank:
  • Does the manufacturer carry liability insurance, and do they list you as one of their “names insured”?
  • Does the manufacturer provide a warranty?
  • Is there a third-party inspection agency that oversees the grading process? (SPIB, WCLB)
  • Does the manufacturer guarantee 100 percent scaffold plank in writing?
  • Does each scaffold plank have a mill/grade stamp?
  • Can the manufacturer supply a certificate of grade upon request?
  • Are the boards identified as “SCAFFOLD PLANK” as their intended use?
No matter what grade you choose, it’s important to know what you are buying and what is behind the grade stamp.
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