There are a number of reasons that foundation cracks occur. In order to repair cracks and address the reason why they are happening, you need to investigate your home’s foundation. Over time, soil around the foundation settles. Water can begin to infiltrate the foundation walls and the concrete expands and contracts due to changes in temperature. The stress of these factors weakens the foundation’s concrete and once cracks begin, they often can continue to grow, potentially into a major problem if not taken care of.
In most cases, you can determine what is causing foundation cracks by the cracks themselves. Settling soil usually causes horizontal cracks and can be thin or wide, depending on the extent of the soil movement. This is usually the most common reason for foundation cracking.
The second most common cause is excessive moisture around the foundation. Too much moisture can lead to water infiltrating the concrete and seeping through to the other side inside your basement, which can spell problems as well. As the water works its way into the concrete, the pressure inside the foundation wall can lead to cracking. In addition, soil swells when it is wet, which creates excess pressure and stress on concrete. Cracks from water usually are vertical or diagonal.
Cracks from expansion and contraction of the foundation’s concrete are usually hairline thin and are vertical or diagonal. These are less of a worry than cracks caused by settling or moisture infiltration, as long as they’re taken care of immediately and not allowed to grow or expand.
If it looks like the crack has caused part of the wall to move away from the rest of the wall, or if the crack is excessively large, call in a professional for an evaluation, as there could be a major structural problem that won’t be cured by a patch.