Don't leave your boards out in the rain
I often see lumber stacked unprotected on job sites. Given the increasing concern about mold problems that develop in buildings, do you think builders should be more careful?
— William Taylor, Richmond, VA
Tom Silva replies: Absolutely. Lumber stacked outdoors without any protection from the weather offers a great habitat for mold. Plus, wet wood is more likely to twist, warp, and shrink excessively as it dries.
The fix is simple: Set the stack on a couple of 4x4s to keep the underside dry, then tie a tarp over the top to keep the wood from getting wet. Keep the stack away from soft ground or muddy areas; it needs plenty of air circulation underneath. Good planning helps, too. Deliveries should be scheduled to arrive when lumber is needed. It's harder to protect stacks that sit around for a long time.
Once a building is framed and roofed, the lumber usually dries out pretty quickly. And when its moisture content falls below 20 percent, mold won't be able to grow on it.