Dry rot is a condition in which structures break down and crack due to certain fungus species. People used to think that it didn’t require any moisture to form, but in reality, dry rot requires moisture. This is why it’s common in basements, where wet conditions often prevail. Dry rot can affect dank wood, concrete, and mortar surfaces. Dry rot doesn’t need as much moisture to grow as other fungi and can develop in conditions containing only a fraction of the dampness levels required by common organisms like molds. In that sense, it’s drier than the norm.