Here in the southeastern U.S., we have a lot of crawl spaces. Most are vented. Even most new ones are vented. It’s not because it’s the best way to keep them dry. That’s certainly not true. We have enough research on crawl spaces to know better. No, they’re vented because foundation vents got into the code decades ago and, once there, they’ve been difficult to dislodge.
So if you have a vented crawl space, especially in a humid climate, it most likely has moisture problems. And where does that moisture come from? Let’s take a look.
1. Plumbing leaks
The first thing you might think of when we talk about water getting into a space is that there is a leak of some kind. A lot of plumbing pipes, both supply lines and drain lines, run through crawl spaces, and they do leak occasionally. Because crawl spaces are visited infrequently, those leaks can go on for a long time before being discovered. This is especially true when a pipe leaks onto dirt or gravel rather than plastic.
One time, we discovered a plumbing leak in a crawl space after we encapsulated it. How many years was it there before we came along? Who knows?
The first photo below (Image #2) shows another source of leaks in a crawl space: the air conditioner condensate line. Those pipes often aren’t installed to the same level of quality as regular plumbing pipes. They also pass lower through the space, making them more susceptible to damage.
Another big source of crawl space moisture is uncovered soil. The second photo below (Image #3) shows our Georgia red clay in a crawl space. The lighter area was uncovered and looked dry. You might think it’s not putting much…