Q. I heard that you said in a webinar that the variation of moisture content for lumber coming into the plant should be 0.3 standard deviation. Is this correct?

Answer. Indeed, I did say something very close to that. I said that the target standard deviation of moisture content should be 0.3 percent MC. So, this means that if the target moisture content is 7.0 percent MC, then two-thirds of the pieces will be between 6.7 percent to 7.3 percent.

Further, no piece should be under 6.01 percent or over 7.9 percent MC. This is a target for the kiln drying operation. If the kilns achieve this value, then any lumber storage also needs to be around 38 percent RH to avoid any significant moisture changes.

I had one customer that began this effort, and they found that 300 call-backs due (mainly wintertime) to dry conditions were reduced to three. This saved lots in repairs, etc. and also the salespeople were not distracted from their main job.

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.