Q. I was looking at historic yield data for our company and see a slow trend toward lower yield. Without visiting our facility, can you guess what it is? I have a suspicion that the lumber grades have changed.

A. It is indeed true that the grade of lumber is perhaps the greatest factor affecting yield. However, there has been no change in the grades for many decades that would affect yield.

Appreciate however that any one grade contains a range of quality in that grade. So, it is possible that the company selling you their lumber has another customer that has special needs or requirements, like wide pieces or no pith. So, you end up getting the lumber of a particular grade, but the best yielding pieces have been taken out and sold to another customer.

Another possibility is that in the past the supplier was generous and included some upper grade pieces in your order. These upper grade pieces, even though they graded higher, were at the low end of this higher grade. Being a little generous would keep you coming back. In fact, maybe now you are getting a few pieces of lower grade within your purchase. Is that percentage increasing?

Or maybe the sawmill has started sawing more RR ties, so that only the logs that do not have the quality for RR ties are the ones that get sawn into the middle and lower grades of lumber.

What can you do? Have your grader, if you have one, give you an opinion about the trend of quality within the grade. Talk to your supplier about your concerns. A good supplier should be willing to work with you.

Of course, there could be equipment or employee issues in your facility too that are causing this loss you are seeing. An outside consultant should be able to analyze your operation.

Gene Wengert, “The Wood Doctor” has been training people in efficient use of wood for 35 years. He is extension specialist emeritus at the University of Wisconsin-Madison.