Reply by Scsmith42

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Posted on Stacking Dried Lumber

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125 posts in 2641 days

#1 posted 08-11-2011 06:44 PM

Hi Rob. I operate a sawmill and kiln drying business, and am happy to share my thoughts.

Actual drying time depends upon species, thickness, and local environmental conditions.

In the CONUS, probably 75% of all wood species dry at a rate significantly faster than “1” per year”. In fact, in most locations and for most species (slow drying species such as white Oak excepted) 4/4 lumber is well air dried within a couple of months, and six months for 8/4.

Here is a link to a US Forest Products Library publication that provides information about air drying tests performed in various parts of the U.S.

The information on page 4 is especially insightful about differences in air drying rates due to temperature and humidity. As an example, 4/4 oak stacked and stickered in early January required almost 5 months to dry down to 20% MC, yet similar species/thickness stacked and stickered on June 1 only requires 2 months.

The biggest unknown for you is the fact that stacked and stickered in your storage building is not conducive to air flow, which greatly assists with air drying.

Most likely your poplar has reached EMC (equilibrium moisture content), which means that it will be around 12% – 14% MC, depending upon your geographic location. The oak has “probably” reached that as well, but oak is a slower drying species than poplar and any 8/4 or thicker may still be over 18% MC.

If you don’t have a moisture meter, the easiest way for your to determine MC% is to take an average board, plane it down to exactly 1” thick, and then cut it to whatever length is needed in order to yield 144 cubic inches. Weigh it, and compare it with charts that list the green and dry weights of various lumber species.

At any rate, if your workshop is climate or humidity controlled, it is really a good idea to stack and sticker the boards for a few weeks with a gentle fan pushing air through the stacks. If you dry stack lumber that has been stored externally (even in a non-climate controlled shed or building), it will not continue to lose MC% unless it is either stickered, or stored vertically (another good option).

The best thing for you to do is to invest a few bucks in an inexpensive moisture meter, such as the mini-lignomat meter. You can usually find a qood quality meter for less than 70 bucks, and the Horror-Freight models sell for about 10, or so I’m told.

Also, watch for any tell-tale signs of fresh sawdust on or around your boards, as this would be an indicator that some pests are present (and you’ll want to either sterilize your lumber in a kiln or via chemical process) ASAP. You won’t need to worry about rot in lumber that has been air dried inside a building (unless the environment was incredibly humid), just bugs.

What thickness is your lumber, and is the oak red or white?



-- Scott, North Carolina,

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