Are you among the first to turn on your home’s heater, or are you one of those proud to hold out longer than anyone else you know? Either way, as temperatures outside plummet, heaters may make things more comfortable for us humans indoors, but have you ever considered how it can affect your lumber? Building with seasonal temperature and moisture level shifts seems obvious when you’re doing an exterior project, but it can also be a factor as you work on lumber in a climate-controlled environment. Let’s take some time to examine the situation.
How Heaters Affect Lumber Moisture Levels
Whether your woodwork is in an area that has central heating or a supplemental heat source, we realize that heat is important — and not just for your own comfort. Most wood glues and finishes will become compromised if the temperature dips below 60 degrees Fahrenheit. However, you need to keep in mind that when you turn on any heat source, it will remove moisture from the air. In addition to chapped lips and dry skin, this drier air will cause a dramatic decrease in the moisture content of any lumber, whether it’s already installed, in the process of being worked, or waiting on your racks.
When you consider the fact that the lumber was typically previously stored in a covered shed, outdoors, or maybe in an indoor facility that’s not climate controlled, you’ll realize that the lumber has been subjected to a pretty significant shift in moisture content already. (Sure, as temperatures drop outside, so do moisture levels — but they’re still nowhere near as low as with artificial heat inside a building!) The air in your workshop may have moisture content dip lower than 6%, ensuring that the wood will begin shedding plenty of moisture when it enters your facility.
What To Expect from Your Lumber
We’re assuming you already know the basics of wood movement: as wood absorbs moisture, it tends to swell, and as wood sheds moisture, it shrinks. Typically this movement occurs due to seasonal climate shifts. Kiln-dried lumber is typically the most resilient to such shifts; however, when moisture levels dip below that 6% mark, even the kiln-dried stuff can become unstable. The result is end checking, particularly if checks have already begun to form. One way to reduce the degree to which checks open up is to trim edges. (You can plan ahead for this issue by purchasing longer boards than your end use will require.) If you see checks on the face of a board, don’t worry; they will close up when the moisture content goes back up.
Unfortunately, warping and cupping can also occur as the moisture leaves the board. Whenever possible, it’s a good idea to keep packs of lumber banded together or weighted in order to reduce warping, while your boards acclimate to their drier atmosphere. While this step is still a good idea for rough lumber, it’s even more significant for milled lumber that’s already at the final dimensions which your application will require.
As you consider the specific issues that can come up with lumber in an artificially heated shop, please check out our next post.
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J. Gibson McIlvain Company
With its headquarters located just outside of Baltimore, the J. Gibson McIlvain Company (www.mcilvain.com) is one of the largest U.S. importers of exotic woods. As an active supporter of sustainable lumber practices, the J. Gibson McIlvain Company has provided fine lumber for notable projects throughout the world, including the White House and Capitol building. Contact a sales representative at J. Gibson McIlvain today by calling toll free (800) 638-9100.