Rule 12 of 31 · Chapter III — Read the Wood
Let lumber acclimate before building
Why this rule exists
Wood breathes. It gives up or takes on moisture until it matches the air around it, and it changes size as it does. Bring boards from a damp yard straight into your heated shop and build immediately, and they'll shrink after assembly, opening joints and cracking panels. Give them a week or two to settle first and they'll do their moving before they're locked into your project, where that movement quietly turns into failure.
In practice
Bring lumber into the space where the finished piece will live, or your shop if the conditions match, and let it sit a week or two, longer for thick stock. Sticker it, meaning stack the boards with spacers between them so air reaches every face evenly. If you own a moisture meter, wait until the readings stabilize and land near your shop's equilibrium. Mill the parts slightly oversize, let them rest again for a day or two, then mill down to final dimension.
When it doesn't apply
Kiln-dried lumber that's been stored in conditions like your shop may already be settled and need little wait. Rough outdoor or utility work tolerates green or damp wood fine. The acclimation discipline matters most for indoor furniture and panels, where a few percent moisture swing cracks a tabletop.