This month I would like to review a few questions that were asked during our Facebook “Live with the Chief” event.
Question: How big of a sound knot is allowed in a sound cutting?
Great question and a point that is quite often misunderstood, especially when grading 2B Common.
Answer: The answer is in the definition of a Sound Cutting, found on page 10, paragraph 31 of the 2019 NHLA Rules Book.
“A cutting free from rot, pith, shake and wane. The texture is not considered. It will admit sound knots, bird pecks, stain, streaks or their equivalent, season checks not materially impairing the strength of a cutting, pin, shot and spot wormholes. Other holes 1/4″ or larger are admitted but shall be limited as follows: one 1/4″ in average diameter in each cutting of less than 12 units; two 1/4″ or one 1/2″ to each 12 units and on one side only of a cutting.”
As the definition of a Sound Knot is written; there is no limit to the size, however, there is a limit on a hole as defined in the last sentence. When the Sound Knot has an unsound center larger than 1/4” in a Cutting less than 12 Units or larger than 1/2” in a Cutting that contains more than 12 Units, then the Sound Knot becomes an unsound knot, due to the size of the unsound portion. Also, as the definition states, this can only be on one side of the Cutting, so a hole larger than a wormhole would be considered unsound.
Question: When inspecting FAS lumber and you have two knots that are not in the first lineal foot and are both under 1/3 the SM but when added together are over 1/3 the SM, is it still an FAS board?
Answer: This question can be answered in the limitations area for FAS in the NHLA Rules Book, page 15, paragraph 60:
“The average diameter of any knot, or hole, shall not exceed in inches one-third the surface measure of the piece in feet, except when it lies entirely within the first lineal foot of a board and is covered by Paragraph 59.”
Read closely; the rule states, “the average diameter of any knot or hole,” which indicates that any single knot or hole cannot exceed the 1/3 Surface Measure limitation. There could be many knots or holes present on the board, providing that the board makes the grade of FAS first.
REMEMBER TO ALWAYS…grade the board first and then apply any limitations afterward.
I would like to invite you to join me for 30 minutes every month on Facebook Live with the Chief. This is your chance to ask questions live and get immediate answers to these types of hardwood lumber grading questions. Follow us on Facebook to see when our next event is!