Moisture Content of Western Red Cedar
A stable wood that is typically serves exterior uses, Western Red Cedar is usually delivered at about 12% moisture content. But you can find it drier than that. July 28, 2006
Question
We are having trouble getting a spec on moisture content as a percentage in KD WRC. We are buying from a well known local source, but they say 15-18% is normal. To me that seems very high. They also say we may be picking up ambient moisture. Any insight would be a great help.
Forum Responses
(Sawing and Drying Forum)
From contributor G:
What is WRC? Some building products are only kiln dried to around 12 to 15 percent, which removes about half of the potential movement (fiber saturation point in most species is around 30%), but everything cabinet or furniture related needs to be kiln dried to the 6 to 8% range.
From the original questioner:
WRC in this case would be Western Red Cedar. Thanks for you reply.
From contributor S:
According to western lumber grading rules, KD WRC lumber can be 15-19% MC or less. MC15 or KD15 is a standard grading stamp. If you need less moisture, then you would have to specify such before purchase. KD moisture content for softwoods is a lot more than hardwoods.
From contributor D:
There are suppliers of WRC who do dry to furniture standards. If you are doing things like interior paneling and trim or high end exterior paneling, trim, furniture etc., keep looking. We (Nyle) have customers who dry for this market, so I know it is available.
From Professor Gene Wengert, forum technical advisor:
It is not unusual to see WRC with this MC, as most of the time it is used outside, so that it close to the outside MC. A MC under 12% is not common at all.
From contributor B:
WRC is one of the most stable woods, so whether it's 19% or 8% doesn't matter much if rift or qsawn. Incidentally, the wood enjoys an excellent reputation as a planking wood among boat builders on the west coast and a poor reputation in the same trade on the east coast. Planks generally require steambending to install. I've always suspected the reason is that most wood shipped east is kilned, and as WRC logs can vary greatly in moisture content, the driest percentage of the boards that enter the kiln get overcooked, making the wood brittle and prone to cracking when bent.
From contributor C:
I stock all widths of C and better WRC (inland) S1S2E, all Selkirk stock. They represent it at that grade, but few defects are found. It is actually higher than C. 19% or lower is what I find in KD. As Gene stated, below 12% is unusual. One would have to air dry it to a lower MC if desired.
From contributor B:
You could wait until August to buy it, whether it comes from WA, BC or OR. Surprisingly dry there in summer. I air dry all my WRC for boat wood and house siding, and have several thousand BF in stacks at any one time. By late July it's approaching 7% EMC and by late September just before the rains, I've had it go so low the Delmhorst wouldn't read it - below 6%.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor L:
The company I work for on the West Coast (northern California) dries lots of WRC (5/4 shop and moulding) to 8-12% MC all the time. We also dry 3x3 and 3x6 Pencil stock to 12-16% MC. I don't think drying to less than 12% is so unusual.
