There are different types of cracks:
Stair-step Cracks – often follow the mortar joints, and is usually the result of uneven settlement of either side of the crack

Vertical Cracks – may not be perfectly vertical but usually passes thru masonry blocks, and is usually caused by shrinkage and thermal movements of the wall.

Horizontal Cracks – usually occurs mid-height of the wall and will exhibit signs of inward bowing. Caused by the soil load pushing against the wall that exceeds the strength of the block or concrete.

Cracks happen for a lot of reasons. In addition to those reasons listed above, here are other common causes of cracks in your basement walls:
- Expansive soils (such as clay)
- Foundation settling
- External vibrations
- Over-saturation of the soil
- Poor Drainage
- Plumbing Leaks
- Trees
Not all cracks leak, but all have the potential to leak if the conditions are right. However, if a crack leaks once, you can pretty much count on it leaking again with each good rain. Solve the problem once and for all by contacting an expert for a permanent solution.