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Tuesday, July 18, 2006

Expansive Soil - Bentonite

If you currently own a home in Colorado, or are planning to purchase one soon, especially along the Eastern "front range", the subject of expansive soils should be of primary concern. Expansive soils cause millions of dollars in damage annually. It is estimated that 50% of the land in the United States has expansive soil, but it is in the populated areas that the effects become most apparent. Colorado & Texas are the two areas of the country most significantly affected by this condition.
With significant real estate development along the Colorado front range in the past 30 years, the problems caused by expansive soil have become painfully obvious. Many people have literally lost their homes due to extensive damage and the high costs of repair. In some cases, class action lawsuits have been brought against builders and/or developers for failure to follow the recommendations of their soils engineers, or for failure to properly disclose the potential risks associated with purchasing a home built on expansive soil."Bentonite" is a term commonly used to describe expansive soil. Expansive soils such as clay, claystone, and shale will "swell" in volume when wetted and will shrink when dried. This volumetric expansion and contraction can cause houses and other structures to heave, settle, and shift unevenly, resulting in damage that is sometimes severe.Minor damage from expansive soil movement can sometimes be repaired for less than $5,000. However, major damage can cost $30,000 to $50,000 and occasionally up to $100,000 or more to repair!
Geotechnical engineering and structural engineering have come a long way in the last 30 years, and specific foundation systems have been devised to help counteract some of the problems inherent with expansive soils. However, the risk of damage to homes can be minimized but cannot always be eliminated.

Here are several good reasons for having your home inspected by a trained professional:
  • Not all homes in Colorado are built on expansive soil. A trained professional knows what to look for to determine if expansive soils are potentially present.
  • Expansive soil can vary significantly in its destructive potential from one area to another, even from lot to lot! An experienced professional can help project the potential future impact of expansive soil on a given home.
  • Some types and styles of construction are more susceptible to damage from expansive soil than others. A professional can counsel you on the home in question, to better understand the risks.
  • Expansive soils can be expected to eventually "stabilize" under certain conditions, but will not stabilize under others. A professional will discuss low cost improvements that will help promote stability.
  • The beginnings of expansive soil related movement can be difficult for the untrained eye to recognize. The experienced professional is trained to recognize "early warning signs" that foretell of future problems.

1 comment:

BS said...

I was so glad to see this article. I am currently in the process of purchasing land in Big Bend Texas which as you know is full of bentonite. Actually my husband is on his way to look at the soil to be sure there is not too much bentonite in the soil before I sign the contract. Our friends who live there are concerned. Do you know someone in that area who could take a look with my husband and give us an opinion?? I sure would appreciate guidance.
Thank you,