As climatic changes from global warming occur and temperatures rise, soils will tend to dry out, resulting in expansive soils shrinking and thus failing to support the weight of buildings. This will likely be a bigger
The potential for expansive clay soils exists throughout much of North America. Shaded areas represent parts of the United States where a risk has been identified. More detailed maps are available at extremeweatherhitshome. com
problem in residential buildings with shallow foundations than with large multi-story commercial buildings with deep foundations. Even though global warming models indicate increased precipitation, this increased rainfall usually does not hydrate the soil. When expansive clay soils get dry they begin to repel moisture instead of soaking it up. The water is more likely to run off creating flash floods. It takes a slow steady rain, over an extended period of time to restore expansive clay soils to a normal condition. Instead, areas are experiencing periods of drought with short bursts of heavy rains that are insufficient to relieve the drought. This is one of the conditions that I recently observed in Santa Fe, New Mexico. The soils had dried out over a period of years resulting in shrinkage. Suddenly in August of 2006 heavy rains broke the drought, resulting in buildings being flooded, arroyos overflowing and flood evacuations in northern parts of the state. Even greater damage is likely to occur in areas with expansive soils if they soak up the water unevenly and expand. When they dry out and contract repeatedly the risks of additional damage to the home is compounded.
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