A lot of woodworking problems can be avoided simply by monitoring the relative humidity in your shop with a simple and inexpensive hygrometer.
In most areas of the United States, the target relative humidity for inside buildings is 35 to 45 percent, though that will vary if you live in a desert or a swamp. So if your shop is in the garage, your basement or the neighborhood cave, you should make an effort to change the relative humidity there to make it match what is inside a typical house.
Why does it matter? There are many reasons. You’ll find that your finishes set up better and your glue dries reliably. But the biggest reason to monitor relative humidity is that you will avoid disastrous wood-movement calamities.
If your shop is drier than your home, your doors and drawers will swell shut. If your shop is wetter than your home, door panels and drawers will rattle in their openings and breadboard ends might crack. Panels are prone to warp more.
As you can see in the photo above, I’m fighting a humidity battle in my new shop with a dehumidifier. Part of the reason the humidity is so high is we’ve just repainted the entire interior and that puts buckets of moisture in the air. The second reason is I have a dirt floor in my shop’s basement, something I’m in the middle of repairing. Within the next couple months my humidity level will be at 45 percent give or take.
— Christopher Schwarz