It’s no secret that wood moves. And between the fact that decking isn’t a finished product and that it often comes from exotic locations, we can expect decking boards to move even more. That’s why decking lumber needs time to acclimate to the moisture levels of its new home prior to installation. Okay, we get it. You already know that general truth. What you’re wondering is how long your decking lumber needs in order to properly acclimate. Well, that’s a great question. And, unfortunately, its answer is far from simple. Like many lumber issues (grading and pricing, for example), many variables affect an acclimatization timeline.
So today, let’s consider a couple aspects of your decking lumber that will impact the answer to your questions. We’ll start by asking some follow-up questions. Yes, we’re answering your question with more questions. But trust us: it’s truly the only way we really can.
What’s Your Weather Like Right Now?
Okay, we’re not asking for a meteorological documentation here. Just be comparative: is it the driest time of year, the hottest, the most humid, or somewhere in between? Here’s why it matters. (It really, truly does.) If the sun heats up your decking lumber in the afternoons, but temps aren’t particularly high, you won’t deal with much movement. Such is typically the case in winter, when air holds less moisture than during the other seasons. Throughout the drier season, your boards won’t experience much movement at all, allowing you to begin working with it almost immediately upon receiving the boards on your job site. (Well, maybe wait a day or so, keeping it stacked and covered. But a single day will probably do the trick.)
Of course, you’ll want to install your decking with season-appropriate gaps so that when they swell during the summer months, you don’t have a deck to repair or replace.
How Finished Is Your Decking Lumber?
This is a biggie. We all know that decking lumber isn’t truly a finished product until after it’s installed. But here we’re talking about whether a finish has been applied. Did you purchase pre-finished decking boards, or do you plan to apply a finish prior to installation? If so, you need to realize that finish typically adds extra moisture to each board, requiring extra time for acclimatization before installation.
If the boards come to you pre-finished, you’ll need to find out exactly when the finish was applied. Also be aware that once the boards come to an equilibrium with their environment, the finish will help them remain stable as temperatures and moisture levels shift — as they inevitably do. At the same time, make sure you’re aware that finish falls short of sealing your decking lumber and keeping it from movement. Wood movement can be slowed, but not stopped.
We do have two more questions for you. Check out Part 2.