Sources of Problems
Expansive soils
In simple terms, expansive soils can act like a new sponge that you would buy at the store. When it is dry, it shrinks; when it is wet it expands. Some soils expand & contract more than others. The strength of these expansive soils have enough power to cause even the heaviest of foundations to move.
Drainage
If you have standing water or water that flows toward the home or under the home, during or after a rain or from watering your yard, damage may be caused to your foundation. When water ponds adjacent to or flows toward the structure, it causes the soils to swell which will raise that area of the foundation or the soil will lose load bearing capacity causing the foundation to sink in that area. Even areas where animals dig can hold water. If the water flows adjacent to the structure or under it, it can cause the supporting soil to erode away.
Vegetation
A large tree can consume hundreds of gallons of water through its roots a day. Beautifully landscaped areas with large shrubs & many plants can, also, take a toll on the moisture levels in the soil. This causes the soil to dry out & shrink (contract). This can make some parts of the foundation move more than other parts. The reverse is true, as well. If large trees have been removed prior to or after construction, the expansive soil can rehydrate where the tree & it's root system were once located. Rehydration may cause foundation movement & can take many years to see its effects on the structure.
Weather Changes
During periods of wet weather, you may notice cracks opening or closing, doors & windows sticking or not sticking. It depends if the soils were moist or dry, when the structure was built, as to how you see evidence of movement. The wet weather causes the expansive soils to expand & dry weather causes the soils to shrink (contract).
Plumbing Leaks
Leaks can cause severe moisture problems underneath a foundation. The soil that is affected will expand causing it to heave therefore causing other problems in the structure. This problem will only become worse if not attended to quickly.