Expansive soils are known to be present in every US state and throughout the world. Every year expansive soils contribute to billions of dollars in damage to homes. In a typical year expansive soils cause greater financial loss to property owners than earthquakes, floods, hurricanes and tornados combined. The proper design and care of your foundation is very important to preserving the integrity of your home.
Foundation watering through the use of soaker hoses has become very important in an attempt to preserve the integrity of your home. Some clayey soils have the ability to shrink or expand at alarming rates, depending on the moisture content of the soil and weather patterns. The goal for proper foundation maintenance should be to maintain a consistent level of moisture in the soil thus eliminating swelling and shrinking of the soil that is supporting your foundation.
If the soil around the exterior of the home becomes excessively dry, it will shrink leaving a gap between the soil and the foundation. These cracks allow additional evaporation and more cracking deeper in the soil. When heavy rains happen, these cracks allow excessive amounts of water to penetrate soil layers causing swelling of the clay soils that are intended to support the foundation. This rapid expansion can cause settlement, foundation cracking, drywall cracking and the need for foundation repairs.
The lack of uniform moisture levels can be caused by:
2. Lack of guttering on the home
3. Improper drainage
4. Plumbing leaks
5. Improper grading
6. Excessive watering
7. Trees too near the foundation
Expansive soils, combined with a shallow foundation, creates a scenario that can manifest itself into major foundation problems. Shallow foundations (foundations very near the surface) rest upon soils that are greatly influenced by rain and ambient temperatures. These foundations become highly susceptible to movement which causes cracking and structural damage. Opposed to deep foundations (foundations that are set below the zone of influence), shallow foundations are cheaper and account for the greatest financial losses due to foundation repairs and structural failures.
Deep foundations penetrate expansive soils providing support for a structure without being effected by shrinking and swelling clay soils. These foundations are most effective when used during initial construction but can also be retrofitted using a high quality end bearing foundation repair system. End bearing is the key here. Foundation repair systems that rely on skin friction fail very quickly when soils dry out and separate from the pile. Deep cracks in the soil are a sign that a skin friction pile has become unsuitable. The highest quality foundation repair systems use slender steel shafts that drive deeply to load bearing soils or rock. Being slender in nature these piles allow expansive clay soils to move around the shaft without negative effects.
To summarize, the expansive clay soils are generally not the problem. The foundation design or foundation repair design is generally the problem. Simply adding water around the foundation most likely will only affect the upper most soil layers which does not solve the problem. Water must be deeply injected into the soil in a wide radius around the foundation to help maintain a consistent soil moisture level. This is generally unfeasible due to the huge amount of water required in dry seasons.
The most effective solution to foundations in expansive soil areas is through professional design. A deep foundation along with proper guttering, grading and landscaping will create an effective foundation for homes and commercial buildings alike without the concern of structural cracking and foundation repair work.
For existing homes:
1. Maintain guttering around the perimeter of the home
2. Direct downspouts at least 10’ from foundation
3. Create proper grading around the home
4. Remove trees and large shrubs that are within 15’ of structure
5. Maintain plumbing pipes beneath foundation
6. Use only high quality end bearing foundation repair techniques
The swelling and shrinking of expansive clay soils create serious problems in shallow foundations throughout the United States. Differences in performance of foundations arise from differences in design and the extent of disturbance of natural conditions. Methods of identifying potentially troublesome conditions and various foundation and foundation repair design to cope with these problems are now available to foundation specialists. Soaker hoses alone will not solve your problem, a trained foundation specialist is generally required.