The Importance of Acclimation
Acclimation is a necessary first step in any Seattle deck building project. Differences in moisture content between the air and the wood can make new deck boards to shrink or expand. If you do not give the wood a chance to adjust to your local climate, this may cause issues such as warps, buckles, and checks in your finished project.
To properly acclimate your decking, you must store them in an environment comparable to where they will eventually be installed. This means they must be kept outside with plenty of space for air flow on all sides. You wouldn't smother your finished deck with a tarp, so do not cover the boards while they're acclimating, either. If you stack the decking, make sure to use spacers between each layer to allow for proper ventilation.