Concrete can shrink as it dries and some cracking can occur. These types of cracks often are hairline and may be random in location. Cracks due to concrete shrinkage may also be travel along an exterior or interior foundation wall, but stop before it reaches the bottom. A crack in the wall that travels into the floor may indicate foundation settling and potential structural issues.
Foundation settling often is vertical movement caused by the wall or footings sinking in unstable soil conditions or by the footings moving upward by the heaving of clay soils. Differential foundation settlement means one area of the foundation is moving, either up or down while the other areas remain constant. You may see cracks in the foundation shaped like stairs because of a differential settlement. It also can cause diagonal cracks.
Diagonal cracks in foundations often are caused by foundation settling, expansive clay soils and tree root intrusion. Expansive clay soils absorb water and swell. The swelling of the soil presses onto the foundation. When the soil dries out, the pressure releases. Clay soils that experience continual expansion and contraction create heaving, which can lead to a cracked foundation. Several areas of the country have expansive clay soils including Kansas, Texas and Alabama.
Sometimes homes in colder regions such as Colorado can suffer from frost heave as well as expansive clay soils. Frost heave is similar to the heave caused by expansive soils. Foundation cracks from frost heave often appear at the foundation’s corners.
Tree Root Damage
Tree roots that extend near or under the foundation can absorb water from the soil, causing soil shrinkage. A large tree can consume as much as 100 gallons daily. Intrusive tree roots also can cause cracks in plumbing located underneath a slab foundation or basement foundation. Water leakage from the pipes can create standing water under the house, resulting in cracked foundations.
Olshan can provide a foundation inspection by a certified structural technician. Determining the cause of your cracked foundation is the first step.