There’s no doubt about it: sourcing high-quality tropical hardwood decking lumber is crucial if you want to build a luxury deck. But as vital as your lumber choice is, allowing for a proper acclimation period is arguably even more significant. And even more influential than waiting for your decking boards to come into an equilibrium with their surroundings is ensuring that they’re installed with the right sized gaps between them. Just like we discussed previously regarding an acclimation period, the question of the perfect gap size is a bit more nuanced than we’d like. Not only is it important for a deck builder to know what size gap is best for your particular setting, season, and species of decking lumber, it’s also helpful for them to be able to communicate their reasoning to their customers. When a customer requests a certain size gap between boards, your response should be to ask what time of year they’d like that size gap.
Board Spacing by Setting: Considerations for Humid Places
If you’re installing a new deck during the humid summer months — especially in a part of the country that’s well known for high moisture content — you have it somewhat easy. When you’re installing a deck when moisture content is at an all-time high, you at least know one thing: it’s only going to shrink from there. Wood fibers act like straws, sucking in moisture from the air surrounding them, causing the board to act like a bundle of flexible rubber straws. The higher the moisture content, the greater the expansion of the bundle of straws. And as the wood fibers expand, the spaces between the boards shrink. If your job site is in the Southeast or Midwest or along the East Coast of North America and you’re planning your installation for the summer months (a.k.a. prime decking season), you at least have that going for you.
Board Spacing by Setting: Considerations for Dry Areas
If you live in a particularly dry climate — out West, for instance — you definitely get the longer end of this stick. Not only do you get to avoid the worst aspect of summer heat, but you also have less fluctuation to think about when it comes to decking lumber. While warm air has more potential for holding moisture, an 80-degree day in Denver, Colorado, will be significantly less humid than an 80-degree day in Atlanta, Georgia. Since wood movement is more affected by moisture content than by temperature alone, those who live and work in drier climates will notice far less wood movement than those in more humid areas.
In Part 2, we’ll take a deeper look at how both lumber species and season will stand to impact lumber movement.