Cracks in foundations may be detected by sensing motion within the foundation. Depth sensors may be applied to a foundation, and the depths of the sensors may be read. At subsequent points in time the depths of the sensors may be read again. If the depths of the sensors are changing in a way that suggests that portions of the foundation are moving apart from each other, then it may be inferred that a crack is forming in the foundation. The formation of cracks may be used to take various actions. For example, the owner of the building that rests on the foundation may be information of the crack so that he or she may take remedial action.