Obtaining the builder's bentonite soils test to determine the swell potential of the soil could save you tens of thousands of dollars later on by simply knowing what property you should or should not buy.  When you have the soils test in hand you will then want to learn all you can about bentonite or montmorillonite clay which is present in soils throughout the metro Denver area. Pure bentonite can expand 15 times it's normal size and exert a pressure of 40,000 pounds per square foot when it becomes wet.  Although we do not have high concentrations of bentonite in our soil, a soils test showing a low 2% to 12% swell potential can result in various degrees of cracking and movement of your basement cement floor, garage floor, drive and walks, and in some cases, even foundation walls. 

Most builders test each building site before they build a home and have the specific swell potential available upon request.  Have the numbers interpreted for you by a qualified person to determine if the swell potential is too great for your comfort level. In recent years, builders themselves are running into a threshold of law suit pain regarding bentonite in the soil.  When the swell potential becomes too high for them, they stop poring cement on dirt basement floors.  They typically construct some form of structural basement floor to eliminate cracking, heaving and/or dropping of cement floors; and the associated eventual law suits.

You will also want to learn what homeowners can do (or what a previous owner have neglected to do) to prevent swelling problems from occurring through proper landscaping, drainage and watering. One excellent publication from the Colorado Geological Survey Department of Natural Resources entitled Special Publication 43: A GUIDE TO SWELLING SOILS FOR COLORADO HOME BUYERS AND HOME OWNERS is available by calling (303) 866-2611 for under $10. You can order it Online too.

Swelling soils requires homes in metro Denver to be built differently than in other parts of the nation. We would be happy to share with you builder construction techniques used in Denver to prevent bentonite issues. And, to show you what you can do to prevent typical owner induced problems.  We also share with you  proper interpretation of builder's swell potential chart. 

Be sure to read:
EXPANSIVE DENVER SOILS - BENTONITE GUIDE: (Expansive Soils - Must Reading Material)