Do your downspouts from the gutters direct water away from your foundation? Often over time the extensions on the downspouts have come off and are missing. This puts the water from the gutter through the downspout to the worst location, right next to the foundation. It makes a soft muddy place below the downspout. This allows the foundation to sink into the mud, perhaps only a 1/10th of an inch per year. Over time this adds up. The foundation may settle or crack and that portion of the house becomes lower. To prevent this trouble, check that all the downspouts on your house have extensions long enough to direct water away from the foundation.