Though each type of foundation crack has unique causes, here is a summary of the most common causes of foundation cracks:
- Concrete Shrinkage: As concrete cures, the top layer can dry rapidly and produce web-like cracks on the material’s surface. Cracks caused by shrinkage do not compromise the strength or integrity of your foundation.
- Settlement: When the soil beneath your home’s foundation compresses or washes away, your foundation settles into the new depth. Settlement can be caused by expansive soils, which shrink when they are dry, soil washout due to heavy rain, or the compression of poorly compacted, loose fill-soil.
- Soil Pressure and Hydrostatic Pressure: Both expansive soil and over-saturated soil can put a large amount of pressure against your foundation wall. If this pressure is too great, it can cause the foundation to bow or buckle and form horizontal or diagonal cracks.
- Construction Issues: Sometimes, foundation cracks are simply due to construction issues. Backfilling a foundation too soon after it has been poured is a common issue, as well as if the concrete is weak, or footings are undersized, reinforcement is inadequate, or fill soil is loose.