FOUNDATION CARE INFORMATION
As Home Inspectors, we want to provide you with valuable information that you can use when making your home purchase decision. Whether you’ve lived in Dallas all your life or you are new to the area, Foundation Care is important to know and proper foundation care and maintenance will help you maintain your foundation.
Maintenance Recommendations For Foundation Care On Expansive Clay Soil
INTRODUCTION OF FOUNDATION CARE
Differential movement of building foundations is a common problem in this area, because of the highly expansive clay soil and changing weather conditions, and costs owners thousands of dollars a year in repair bills. As the building ages, it is probable the foundation will continue to experience differential movement, regardless of how well it was constructed or its present condition. This differential movement does not stop as buildings become older; older structures with a history of minimal differential movement have been known to develop foundation problems in a very short time due to changing conditions at the perimeter of the building foundation.
REASON FOR FOUNDATION CARE PROBLEMS
The primary reason for foundation problems is the highly expansive nature of the clay soil on which the building rests. The clay expands or contracts as its moisture content changes with the weather. Depending on the area, the amount of contraction or shrinkage ranges from minimal to upwards of 65% of the total wet volume. The average amount of shrinkage that can be expected in this region is approximately 35%, with wide variation depending on the location.
EFFECT OF PLANTS ON FOUNDATION CARE
Because of the highly expansive nature of the soil, trees and other large plants can significantly contribute to differential settlement of a foundation. The roots of trees and large plants consume the moisture from the soil, causing the soil to shrink much faster than other soil areas exposed to the weather.
EFFECT OF WET SPOTS ON FOUNDATION CARE
Wet spots caused by dripping faucets, leaking drains, air conditioning condensate drains, leaking water pipes, etc., can cause differential settlement at the location where the soil has been kept wet.
EFFECT OF POOR DRAINAGE ON FOUNDATION CARE
Water standing or running alongside a foundation after rains may cause differential settlement of a foundation. If soil grading is such that water runs alongside a foundation during rains, the water will run under the edge of the foundation and carry away soil supporting the foundation. The effect is much more pronounced if the soil was very dry prior to the beginning of the rain.
An owner can significantly reduce the rate of differential settlement by observing the following recommendations:
- Try to maintain constant moisture content in the soil around the foundation. Water the soil evenly and around the entire foundation during extended dry periods.
- Cut and cap the roots of any large trees growing closer to the foundation than the mature height of the trees. The roots from trees can consume more water from the soil than can be added with a watering system.
- Properly grade the soil by filling in low spots and leveling off high spots adjacent to the foundation so that the surface of the soil slopes gradually away from the building. A recommended slope is 1 inch per foot for a distance of 3 to 4 feet from the foundation.
- Control roof water runoff and help prevent soil erosion by using a gutter and downspout system. This is especially important if a building has no eaves which overhang the walls or if the eaves are less than 1 foot wide.
- Water trees and shrubs growing near a building during extended dry periods as they cause shrinking of the soil due to their high water consumption. Keep in mind that moderate to large trees consume 50 to 75 gallons of water from the soil every day.
FOUNDATION CARE SUMMARY
Remember: the intent of foundation maintenance is to maintain a constant moisture content in the soil around and below the entire foundation and to prevent soil erosion that can result from water flowing off the roof or other large flat surfaces near the building.
Adapted from an article by: D. M. Robinson, Registered Professional Engineer, #23598,
PROFESSIONAL ENGINEERING INSPECTIONS, INC