General Recommendations for a Foundation Watering Maintenance Program for Most Structures in the DFW Area
Your house is founded over highly plastic clay soils. The highly plastic clay soils are characterized as very expansive or possessing high shrink-swell potential. Simply, these expansive soils have the ability to shrink and swell when becoming dry and swell to a large volume when wet. Seasonal moisture variations, vegetation, and precipitation pattern directly affect this sponge-like behavior. In Texas, the clay typically swells in the winter and spring (wet months) and shrinks in the summer and fall (dry months).
When your house was built and the yard and landscaping installed, the natural effects of climate and precipitation on the soils around the home were modified. Over the long term, the soils will tend to become wetter under the center of the house and will seasonally dry out and shrink near the edges. When these moisture variations occur, the underlying clay experience shrink-swell cycles, and the foundation will attempt to conform to the shape of the supporting soils. This can result in movements of the foundation which in turn, stress the walls of the structure above it, i.e. your house. Eventually, after repeated cycling, stress cracks will appear in the walls and grade beams. Once the cracks appear, they may become progressively worse at an accelerated rate if shrink-swell cycles are allowed to continue.
Your builder recognized the activity of the soils in this area and designed and constructed your house foundation to accommodate the soil movements as much as possible. While it is virtually impossible to eliminate all movements, controlling the moisture content and keeping any variations relatively constant throughout the year can minimize them. The soil volumes will then remain relatively constant and any related movements are minimized.
As a homeowner, you can control these moisture variations by implementing a program of proper foundation watering. The purpose of such program is to maintain a high, uniform moisture level in the foundation soils by restoring the moisture lost to seepage, evaporation, and plant transpiration. This watering can be accomplished by both proper lawn and landscaping maintenance or by a separate foundation watering system using soaker hoses or drip irrigation tubes. In either case, artificial precipitation equivalent to approximately one inch of rainfall per week should be applied evenly to the soils near the foundation. Obviously, watering can be postponed if the natural precipitation is sufficient. The water should be applied slowly to allow absorption and prevent run-off.
To verify the adequacy of the watering program, surface soils should be routinely checked for shrinkage, cracking, and/or pulling away from the foundation. If either condition develops, of the landscaping shows moisture stress such as wilting or leaf drop, the frequency and amount of watering should be increased. Root growth of trees and shrubs should also be directed away from the foundation by adequate watering and fertilization of the yard away from the house. It should also be noted that sprinkler systems alone will seldom supply the needed moisture to soils.