How do freezing temperatures affect woodworking?

Q:

With the temperature dropping below freezing in my unheated shop, I’m worried about wood movement. Does frozen moisture in hardwood or sheet goods make the wood expand? Will shrinkage make joints and reveals sloppy when I bring my project inside?
—Gary Kosin, Chisago City, Minn.

A:

Gary, keep in mind the old adage “It’s not the heat, but the humidity” when considering wood movement. Most properly dried lumber and sheet goods won’t have enough moisture content for their dimensions to be affected by freezing temperatures.

In fact, the expansion will most likely occur when you bring your project inside rather than when it is out in the cold of the shop. Winter weather often brings drastic drops in humidity. A completed project that is brought from the dry winter weather into the warm house where you steam vegetables, take hot showers, and exhale moist air, will experience expansion—primarily across the grain—as it takes on the moisture of its new, warm surroundings.

However, there are a few ways to design your project to account for the change in humidity it will experience: Install drawer dividers using sliding dovetail joints that won’t restrict movement across the grain of the case. Attach tabletops with sliding clips rather than fixing them in place. Allow extra room for panels to expand widthwise in their frames. Likewise, allow extra clearance for the width of drawer faces.

Finally, despite its dryness, winter weather slows drying times, and freezing temperatures bring drying to a halt. Acclimate your project in a warm place for a few days before proceeding with glue-up, finishing, and drying.

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