During the colder winter months, the boards in your climate-controlled shop are subjected to an unnatural degree of dryness; in a previous post, we talked about how to avoid significant issues that can stem from exposure to such an environment. Now we’re going to discuss how to prepare those same boards to leave such an environment, which they’re of course bound to do. By being proactive and taking a few preventive measures, you can reduce the chances of problematic wood movement in the future.
Provide Extra-Large Expansion Gaps
The boards in your shop right now won’t stay there; wherever they end up, the moisture levels will be higher than they are in your shop during the winter. When they’re exposed to climbing moisture levels, the boards will soak up that extra moisture, causing rapid expansion. Decking boards or ship laps need to be installed with extra gaps, and tongue and groove applications need to have an extra expansion gap figured in to the outer edges. Even drawers should be fitted loosely to their cabinets, leaving room for the wood fibers to expand.
Of course, as you plan for any specific board’s future, you need to consider the technical specs related to its species; since boards become extra dry if they’re subjected to a climate-controlled environment during the winter, count on at least the average amount of expansion, maybe more.
Prepare To Restrain Boards
Depending on your application, maybe an expansion gap isn’t in order; instead, you may need to restrain a flat board from dramatic cupping, during seasonal moisture shifts. What you can do is secure a board along one edge, or in its center. By doing that, you can direct the movement. You could trap the board in a groove, serving to hold the board flat even when it does expand across its width — as long as you have left enough of an expansion gap into which the board can move.
Don’t Try To Prevent Movement
The word “restrain” is important in this discussion, particularly as contrasted with “prevent”: you cannot stop wood from moving. What you can do, though, is guide the wood to move in a certain way when it does move. After all, wood movement is pretty powerful: think of how they once used wooden wedges to split stone, simply by pouring water over them, producing expansion. Any attempts to prevent wood movement will result in cracking or buckling, and trust us — you don’t want that to happen.
Once summer comes, good winter construction will become obvious, and those who have left extra room for boards to move will reap the rewards. Those who neglected to take those extra steps will, just as certainly, regret it.
