What Is Expansive Soil?

By Justin Sexton

What Is Expansive Soil?

Expansive clay is a soil that is susceptible to swelling and shrinking. It is directly related to changes in the water content.  

Expansive soils are referred to by many names. "Expandable soils," "expansive clays," "shrink-swell soils," and "heavable soils" .

Expansive soils contain minerals such as smectite clays that are capable of absorbing water. When they absorb water, they increase in volume. The more water they absorb, the more their volume increases. Expansions of ten percent or more are not uncommon. This change in volume can exert enough force on a building or other structure to cause damage.

Expansive soils will also shrink when they dry out. This shrinkage can remove support from buildings or other structures and result in damaging subsidence. Large cracks in the soil can also develop. 

This cycle of shrinkage and swelling places repetitive stress on your home’s foundation, and damage worsens over time.

Although expansive soils can be found in almost every state, the problems related to expansive soils are the most severe and widespread in California, Nevada, Arizona, Colorado, and other Western and Southern states.


Did you know?….

Each year in the United States, expansive soils cause $2.3 billion in damage to houses, buildings, roads, pipelines, and other structures. This is more than twice the damage from floods, hurricanes, tornadoes, and earthquakes combined.

Nowadays, builders are required by law to have a Geotechnical Engineer (G.E.) prepare a soils report to identify expansive soils and give the builder recommendations to build a home that will withstand these soils. These recommendations often include removal of the expansive soils, importation of non-expansive soils, soil chemical treatments, a post-tensioned or structural floor foundation, piering systems down to bedrock, gutters and downspouts.


If you think that you might have expansive soils, and are concerned it might be impaction the health of your home's foundation, give us a call!

Tags: Causes

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