Mushrooms on your burger with swiss cheese? Yes, please! Mushrooms in your crawl space (with or without cheese)? That’s a big NO. Mushrooms love and need the one thing you absolutely do NOT want in your crawl space or basement – moisture. I know we sound like a broken record, but we can’t stress enough how important it is to keep your crawl space dry. If it’s wet enough to grow mushrooms, it’s wet enough to grow other organic material like mold and over time, it can compromise your foundation as well. Plus all that moisture has a tendency to creep up into your living space.