The WCK Foundation Repair Blog

Foundation Repair Baton Rouge

Posted by WCK Foundation Expert Team on Apr 6, 2012 1:14:00 PM

expansive soil

Photo provided by Geology.com

What is an "Expansive Soil"?

In Louisiana, the soil conditions are unique.  There is no rock or consistently solid ground for thousands of feet below the ground. The soil here is very expansive clay, which is usually titled smectite clays, which are a family of clays that swell when immersed in water.  According to the map on Geology.com, over fifty percent of the soils of South Louisiana consist of clays with high swelling potential.

This soil contracts and expands drastically with moisture changes in the soil. The subsoil layer (approximately 5 to 20 feet below the surface) is extremely unstable. We have commonly found very hard, dry soil when drilling one hole, then very moist soil when drilling the next hole just a few feet away.

According to Geology.com, the expansive soils, like the soils of South Louisiana, increase in volume as they absorb the water. The more water they absorb the more their volume increases. Expansions of ten percent or more are not uncommon. In South Louisiana, we experience very frequent and heavy rainstorms.  The more consistent the rainstorms, the more likely our soils experience this change in volume. This change in volume can exert enough force on a building or other structure to cause damage. 

Cracked foundations, floors and basement walls are typical types of damage done by swelling soils. Damage to the upper floors of the building can occur when motion in the structure is significant. 

After all the recent spring rain fall in South Louisiana, the best time to repair a foundation is now while the soil is expanded.  With the soil being soakded, WCK Foundation Repair has less to lift, which causes less structural issues and reduces the chances of additional movement in the future, when the soil shrinks again. Expansive soils will also shrink when they dry out. This shrinkage can remove support from buildings or other structures and result in damaging subsidence. Fissures in the soil can also develop. These fissures can facilitate the deep penetration of water when moist conditions or runoff occurs. This produces a cycle of shrinkage and swelling that places repetitive stress on structures.


If you are seeing signs of damage from an expansive soil or if you want a free assessment on your home or building, call the experts at WCK Foundation at 225-664-5956.  Or, just log on to www.wckfoundationrepair.com and fill out this free estimate form.

The Expert Team
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