Why Do Foundations Sink?

By Shawn Kyles

When a foundation settles, it can cause considerable damage to a home, including uneven floors; bulging, leaning or bowed walls; a chimney that pulls away from the house, windows and doors that don’t close properly, wall cracks, ceiling cracks, baseboard gaps and other structural problems.  A foundation will sink when the soil it was built on has a high clay content that causes it to expand and contract, or it wasn’t properly compacted when the foundation was built. Because the settling is almost always uneven, it causes foundation problems and building damage.

Water, including rain and water from sprinklers, down spouts, condensation from an air conditioning unit and broken pipes, is the basis of most foundation damage. It causes soil to expand, which can quickly become a problem when it seeps beneath a foundation.  The amount of soil expansion will depend on the composition of the soil, and is rarely uniform. 

When the soil expands, it lifts the foundation; when it dries, it contracts and creates a void.  A concrete foundation will sink into the void created by the soil’s contraction.  Other causes of soil expansion that you should be wary of include overwatering and uneven watering.  Soil expansion and contraction can occur over and over again throughout the year, causing numerous foundation cracks and other damage. Eventually it will affect the structural integrity of the building, and may even lead to a collapse.

A foundation will also sink when the soil around and underneath it hasn’t been compacted correctly.  Excessive foundation settlement will usually occur when the soil is too loose, and can result in cracks and breaks. Settlement damage can also result from poorly planned landscaping.  The roots of large trees and dense foliage planted too close to a home will dry out the soil around and under a foundation.  When the roots absorb the water from the soil, the soil will contract, leaving empty space below the foundation that will cause settlement.

There are many ways to prevent foundation damage, beginning with an inspection by an experienced foundation repair expert. A foundation specialist will be able to determine if you have any water issues that need correcting, and can indentify other potential problems that could result in foundation settlement, cracks and breaks.  If your foundation is already damaged, it should be fixed as soon as possible. The longer you wait to repair a foundation issue, the worse it will get. 

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