Understanding How Hardwood Lumber is Graded

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Barry and I recently toured the yard of one of the largest, oldest and most prominent hardwood importers in the country. McIlvain Lumber. That’s right, we met with Shannon Rogers, the dude behind the tweets @McIlvainLumber. Located literally right around the corner from where I grew up — from where my mom still lives.

Quite simply, it was a thoroughly fascinating tour. And Shannon knows a lot about wood, working with wood (important here) and (surprisingly) he knows an awful lot about the internets too. A prolific blogger in his own right, a feature maybe on the way, but not today. Today, a re-print from McIlvain Lumber‘s blog (with Shannon’s permission).  Enjoy! ~jb

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Understanding How Hardwood Lumber is Graded

For more than a century, the hardwood lumber industry has held to a central grading standard established by the National Hardwood Lumber Association (NHLA). Thanks to the foresight of the early founders of the NHLA in 1898, some order comes to the chaos that had become the lumber trade.

A standardized system of grading to determine quality of lumber. Today we take this grading system for granted. It is now simply a universal way to quickly convey the quality of a board and how much clear wood can be had in each board.

Keep in mind that NHLA grades apply only to North American Hardwoods. The minute Mahogany, Ipe, or Teak becomes part of the equation, a different set of standards are observed. These are usually much more specific to the species.

At the turn of the last century when NHLA standards were set up, the furniture industry was still leading the pack in hardwood lumber consumption. So it follows that many of the specifications were based around the needs of the furniture maker. First and Seconds (FAS) and Common grades all specify a minimum amount of clear wood cut from the overall board. All grades have a minimum percentage. So your FAS board is actually 100% clear, but not considered FAS.

Let’s take a quick look at these grades

(Editor’s Warning: Technical stuff immediately below).

FAS

Both faces must meet these guidelines:

FAS 1 Face and Select

This grade developed later where one face may be of FAS quality, but the other of at least a No 1 Common grade. Select requires the same stipulations but now the minimum board size reduces to 4″ x 6.

No. 1 Common

No. 2 & 3 Common

* Identifying Defects

The important element to consider is what is actually considered a “defect”. In other words, what will interrupt the clear face.

The following is considered unacceptable by NHLA standards:

• Split
• Knots of any kind
• Checks, Splits, and Bark Pockets
• Pith and/or Wane
• Worm or Grub Holes
• Wane
• Bird Pecks
• Rot or Decay
• Sticker Stain from kiln or air drying sticks

Knot

Split (Walnut)

Wane

If any of these elements are present, they interrupt the face and reduce the size of the cutting that is obtainable.

* Acceptable Defects

However, the following elements are considered acceptable and will not affect the cutting sizes (More with the techy techy):

• Sapwood to Heartwood transitions
• Mineral Streaks or Tracks like Glassworm in Ash
• Burl
• Sticker Marks (can be removed with planing)
• Gum Streaks

Sapwood

These elements do not effect the structural integrity of the lumber and in many cases can be seen as appealing character depending on the industry and final use.  It is this variance of opinion that NHLA grading systems cannot possibly take into account and therefore where the system begins to break down.

* Decoding Defects

The old cliche, “one man’s trash is another man’s treasure” could apply here.  For example an 8″ x 9′ board  that has several knots, wane, and soft, rotten wood would probably never pass the test to be a No 2 Common board.  However many furniture makers would prize that piece for the unique character it contains and even design entire pieces around those “defects”.

That same board when viewed by the flooring manufacturer is immediately rejected for instability and lack of consistent appearance.  Likewise an FAS board that meets the grade because the only “defects” present are sapwood and some curly and burl figure would probably meet the same fate.  The furniture maker or luthier loves it. But the flooring and window manufacturer would reject it. It really comes down to how the lumber is to be used and what unique stresses it will be subjected to.

You can see that simply requesting 1000 board feet of 4/4 FAS Maple may not be descriptive enough and you can still end up with lumber that won’t meet your needs.  Some species are graded differently from others due to natural factors in how that tree grows. Check out this post on Walnut for more information on that topic.

The Grading System is a Communication Tool

This is not to say that the grading system is broken by any means. Rather, it’s important to remember, it is just a starting point to get everyone on the same communication plane. NHLA provides these guidelines but encourages communication (and negotiation) between buyer and seller. They help guide the discussion around what is needed and the quality required.

This is a smart move, otherwise, grading systems become more and more detailed and cumbersome thus increasing lead times and man hours. Eventually this unnecessarily drives up the prices. Use the grade as your guide, but have a clear understanding of what you need to use your lumber for. In other words, what “defects” are acceptable. The appropriate grade is determined but also what is not covered in the grading structure.

Overall, an educated buyer helps everyone.  If you understand how grading works and it’s limitations, then you can help your lumber supplier to provide the best quality product to suit your project.  Whatever that project may be.

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This article was originally published here. I promise a more robust post on our visit hopefully next week.

For more on working with Lumber, you might see our related article on the Pros and Cons of Reclaimed Wood.

~jb.  Out.