Colorado, especially the Front Range, is classified as having two types of soil existing together: expansive and hydro-compactable. Most soil in the Front Range can be classified as a swelling soil. This means that the soil contains a high percentage of certain types of clay that absorb vast quantities of water. This can cause the soil to expand 10% or more as moisture enters it, usually during winter snow melt and spring run off. The soil can then exert pressures of 20,000 psi or greater on foundations, slabs, and other structures. Now, this soil also contracts when the moisture evaporates during our hot summer months, causing extreme differences in the pressure being generated on your foundation, driveway, or patios.
Homes built on expanding clays can be structurally damaged as the clay swells with increased water. Cracks will appear in walls and floors. Damage can range from minor to severe enough for the home to be structurally unsafe. The American Society of Civil Engineers estimates that half of the homes in United States are built on expansive soils and half of these will have some damage. The group claims that these soils are responsible for more home damage every year than floods, tornadoes, and hurricanes combined.
Thankfully, expansive soils are so common place that many engineered solutions have been developed to resolve damage and return structural stability to a home.
Some indications that you are dealing with expansive soils are:
If you are experiencing any of these problems, it's important to be proactive. The longer that expansive soils exert pressure on your foundation, patios, and sidewalks, the more costly and difficult fixing those problems can be.
The potential for structural damage often can be minimized or the damage avoided altogether by following certain landscaping practices. On expansive soils, the main landscaping goal is to minimize fluctuations in soil water content. Proper surface drainage, plant choices, sprinkling practices, and long-term maintenance are all important. In areas that are constantly moist, the soil should be kept in that condition during extended dry periods. In the more arid areas, excess moisture and landscaping should be kept several feet away from the foundation. Surface drainage and downspout outlets should be maintained away from the foundation. Trees should be planted no closer than 15 feet from foundations. A distance of 25 to 30 feet is best. Tree roots withdraw sufficient water from soils to cause drying and cracking.
Expansive soils do not swell and shrink if the moisture content remains constant. Sprinkler lines should be installed away from the house. Applying water selectively near the foundation walls helps to maintain a consistent moisture condition.
Unfortunately, cosmetic repairs such as new paint or stucco will not fix problems caused by expansive soil. That's why it's important to have a professional service company to come in to your home with warranties and guarantees to protect your investment. The service company should hire an independent, professional Geo-technical Engineer can make a site inspection and perform laboratory tests. After analyzing your particular situation, he can make recommendations specific to your property.
Please see expansive soil distribution map.
 |
 |
 |
 |