John Temmel Siding Guy believes in investing the money in quality deck lumber. Here’s why. Standard lumber goes through a pressure treatment process before it gets shipped. During this process, the wood is injected with chemicals to preserve it so that it won’t rot. When the wood finally reaches the customers, there’s about 40% moisture in that wood from the chemicals. This means that when you build your deck, the wood will dry out because the moisture tries to escape, which results in a cracked and unpleasant looking deck after several months. The best way to get a beautiful, quality deck is to obtain wood that goes through the following process: Kiln-Dried-After-Treatment (KDAT). During this process, the wood is placed inside a kiln and dried so that when it’s delivered to the customer, there’s only about 15% moisture in the wood. That’s a difference of 25%, which makes a huge difference in the aesthetics and quality of your deck. Although this type of upgraded lumber can be pretty costly, it’s well worth it if you want your deck to last.