When vertical cracks in poured concrete walls are found, they are usually located at the corner of a window opening. Inside corners for a window opening are a natural weak spot in the walls. Sometimes a vertical crack will appear in an open area of a poured concrete wall. Many times, this is just a normal occurrence from settling.
A vertical crack that is buckling or bowing in toward the basement can be a more serious problem. This may indicate that the wall was fractured or cracked during backfilling operations or that there is inward pressure against the wall.
Vertical Cracks in Block Walls: Vertical cracks in block basement walls can be a sign of trauma. The outside wall may have been struck by a large rock or boulder during the original backfilling when the home was built. They can also be cause by tree roots pressing in toward the foundation.
Vertical cracks in block walls
Step Cracks: When basement wall cracks appear in a "step" pattern, this is a sign of settling. These usually mean that part of the block foundation settled lower than the rest, causing step cracks to appear.
Remedies: If the basement walls are badly damaged, they may require replacement. This can be a very expensive option. If the walls are generally stable, they can be supported with soldier piers, steel I-Beams or other means.