Where do cracks come from? Why are they here? Where are they going? have puzzled philosophical homeowners for centuries. The short answer seems to be that cracks can be caused by outside forces beyond our control such as an errant 18-wheeler, a settling foundation, or water pressure build up around and/or under your foundation. *Its movement that causes your foundation wall to crack. Of course, if you had an average of 47 tons resting on you, you'd crack too.