Maintenance by the building owner plays an important role in ensuring acceptable long-term performance of structures built on expansive clay soil. Important areas for maintenance include irrigation, drainage and landscaping. It is also important that the owner have realistic performance expectations. The key point to owner maintenance is understanding that movement of buildings constructed on expansive clay soil is driven by changes in the moisture content of the supporting soil. Thus, the owner must take steps to ensure that the moisture content does not experience significant changes.

Irrigation
 
Proper irrigation is important. The full perimeter of the structure should be irrigated. During hot dry periods, irrigation must be increased. During cool, dry periods, irrigation must be stopped or decreased. Generally, the amount of irrigation water should be limited to an amount that keeps the adjacent vegetation healthy. Do not saturate the soil or allow the soil to become desiccated.

It is our opinion that "leaky hose" should not be used for perimeter irrigation. It has been our experience that this type of hose does not deliver a consistent quantity of water along the length of the hose. Consider the installation of a perimeter drip irrigation system instead.

Some companies will install irrigation lines under the foundation prior to construction for the expressed purpose of maintaining the soil moisture content. It is our opinion that these system should not be installed. There are several reason that we feel these system should not be used. 

1. The soil under the foundation does not generally require supplemental moisture, if the perimeter is properly watered.
2. Since the system is burried under the foundaiton, there is generally no way to know if the system is malfunctioning, resulting in either underwatering or overwatering the soil. 
3. There is generally no way know the moisture conent of the soil under the foundation. Thus, it is difficult to know if a proper amount of water is being applied.
4. When the system does malfunction, it is costly to repair.

Drainage

Do not allow water to pond witching 10 feet of the building perimeter. Ponded water will eventually seep into the soil and cause a localized increase in the soil moisture.

Do not repair low areas using sand. Sand holds water and is ineffective for improving drainage. Instead, fill low areas using clay soil.

Landscaping

Do not plant tree closer to the foundation than about half the trees mature heght. Trees can remove large amounts of water fromt the soil  causing structural settlement, Conversely, if there large are pre-existing trees near the foundation, it is critical that these trees

Performance Expectations

Be realistic about your performance expectations.

If you are constructing a new building and are adverse to any cracking or distress to teh finsihes, discuss this with your architect and strucutreal engineer so the the buildign cen be designed accordingly. This will require the use of an elevated  structural  slab which will also cost more some.