What causes foundation cracks?

Answer 1

The majority of cracks in concrete foundations are a result of shrinkage in the concrete. Shrinkage is a normal occurence and should not be a cause of great concern. Fixing cracks yourself can be done through a process called low presssure crack injection. Urethane is forced into the crack sealing the crack all the way through the wall. The process takes about one hour and a typical kit costs about $100. DIY kits can be purchased at www.thebasementoasis.com or contractor can be found through contacting www.cmemanufacturing.com.

Answer 2

broken underground water pipes cause cracks when gone un-noticed due to water sucked into the concrete--water freezing and then spreading the concrete molecules apart

Tree roots also cause foundation cracks when large trees are planted too close to the house or vice versa.

there is also the shifting of land and the settling of a newly built home that goes un-detected as time passes by.