Checking of Dry Lumber

Checking occurs when the wood is very wet. Checking that appears in lumber purchased as kiln-dried is a defect. December 8, 2012

Questioner
We purchase kiln dried lumber for our facility in Southern California. When we buy import woods like ipe and limba, we sometimes lose a good 10-30% to checking and splits. It rarely happens with domestic woods. We're inland and get spells of high winds and low moisture.

My guess is the wood comes in 8-12% and high winds suck the moisture out so fast the boards don't just move, they split. Our warehouse is enclosed on 3 sides but indoors. We do check moisture content upon arrival, so I'm sure it's not coming in too wet. Any ideas/suggestions to help eliminate or minimize this problem?

Forum Responses
(Sawing and Drying Forum)
From Professor Gene Wengert, forum technical advisor:
Checking occurs when the wood is very wet, not at low MCs. So you are seeing preexisting checks that are reopening. If they do not reopen in your shop, they will reopen in the customer's home. The lumber you are buying is defective. You are not checking it. This is 100%.

---

From the original questioner:
Hi Gene, if that's what's happening, how can we spot this problem and address it with the mill during the check in period? Most of our imports arrive in the rough. I've watched 1000' go through the planer with no sign of checking, only to lose 20% of the unit to checking 1 1/2 weeks later.

---

From Professor Gene Wengert, forum technical advisor:
If you inspect it when the humidity is high, you will seldom see checks. So, inspect on a dry day and let the surface dry a bit first. Or you can cut a surface check sample, as shown in Drying Hardwood Lumber... page 100 or so.