Lumber Grades – What Do They Mean to Me?

Nov 09, 16

One of the very first questions we ask most customers when they contact us is either "What grade are you looking for?” or something less direct along the lines of “What are you building with this material?”.  While lumber is an excellent renewable resource, it doesn’t make sense to throw beautiful lumber at every project. So at Marks Lumber we offer lumber of all qualities, and work with every customer to make sure they get material that will work well for them.  So we have to determine what type or quality of lumber you need.

The way we deliver the right product is by grading all our timber products.  Marks Lumber uses the standard grade guidelines maintained and published by the Western Wood Product Association (WWPA).

Overview - How Lumber is Graded

Lumber is graded relative to how it will be used practically. So lumber for different purposes is graded differently. Generally lumber is graded by characteristics that affect strength and appearance. 

Key characteristics affecting strength

  • Knot size
  • Slope of grain
  • Bow/crook
  • Twist

Key characteristics Rough Cut Appearance

  • Bow/crook
  • Twist
  • Fir – lack of black marks
  • Lack of mill marks
  • Knot size, knot health – black knots

Lumber that is 2 inches or thicker is graded for both strength and appearance. Lumber and lumber products that are less than 2 inches thick are only graded for appearance.

Applying these Characteristics

Products manufactured at Marks are graded manually by well-trained graders. For stock items and blanks for planed items, Marks sets up and grades a specific dimension. For example, let’s just say 1x6x8.  Generally, normally, and usually the grader will call boards into 4 grades.

  • RT – This is a #2 and better grade optimized for flooring.
  • #2 – These are appearance grade and very nice boards.
  • #3 – Good quality boards.
  • Cull – Will stay together, good for windbreak.

When grading beams or 2 inch material we stock 3 grades:

  • Select Structural – Very high quality –Graded for appearance.
  • #2 – Quality boards, but having some defects. Not graded for appearance.
  • Cull – Good enough to make dunnage.

At Marks Lumber, we want to deliver quality material with value. To do that we grade lumber and sell the right lumber for the job at hand.

What Grade do You Need?

People generally can tell if an individual board or timber is going to get the job done. What grade is it?

If you are using the material for trim or furniture you will need a #2 and better grade.

Siding? We generally recommend #2 and better for homes and commercial buildings. For outbuildings and agricultural buiildings, #3 is fine.

Fencing? Grade #3 for nicer fences; but for windbreak lower grades are acceptable. 

What else are you building? Talk to the friendly, knowledgeable team at Marks Lumber and we will help you out!

Note: The WWPA grade book anticipates 5% error for grading mistakes and material that ‘moves’ significantly after grading.

If you have questions about lumber grading, let us know!

Other Posts


Marks Lumber Mill Tour

Montana Forest Products Week - Event October 20TH 10 am - 2 pm Marks Lumber is excited to host an official Montana Forest Products week event at our ...

~ View Now ~

Why You Should Be Using End Matched Wood Flooring

End Matching At Marks Lumber, we end-match our circle sawn Douglas Fir flooring, saving our customers significant time and money. End matching involve...

~ View Now ~

Steve Standing Up For Montana's Forests

And our Montana way of life….. The Big Boss at Marks Lumber, Steve Marks, had the chance to debate forest management policy and the role that serial l...

~ View Now ~