Foundation Maintenance

Controlling the moisture levels of expansive clay soils around your home is critical to minimize movement of the foundation, walls and structure and to prevent many serious and costly foundation problems.  The following identifies ways to help stabilize and then maintain moisture levels under your foundation.

Drainage:  Soil moisture control must begin with good drainage.  The moisture level must not be too wet (muddy) or too dry (cracking).  Areas with poor drainage are especially prone to going from one extreme to the other.  If this poor drainage area is near your foundation you hone will be moving up and down as the expansive clay soil expands and contracts.  The following identify some specific items to consider:

• The soil for the first 5 feet from the base of the foundation should be non-sandy clay firmly compacted.  Soft sandy landscaping soils should begin greater than 18 inches and be shallow.
• The soil should slope away from the foundation a minimum of 1 inch per foot over 6 feet.
• The soil level should cover the foundation’s perimeter beam up to approximately 4 inches below the brick or 6 inches below siding.
• Rain guttering is not required.  However, where guttering exists, the downspouts should be extended away from the foundation 12 to 18 inches and land on splash block to prevent erosion.
• Water should always run away from the foundation.  There should not be any ponding of water near the foundation.  In areas where drainage cannot be obtained by sloping soil, a surface drain must be installed.  Care should be given to size it correctly and to keep it clean and working as designed.

Changes in moisture levels can shrink or expand clay soils by 30 percent.  This can easily translate into inches up or down of sidewalks, driveways, patios, or foundations!  Many homes in this area are built on several feet (up to 10 feet or more) of expansive clay soil.  To control movement of the foundation, the moisture level throughout this layer of clay must be controlled.  Simply watering the surface around the home may not be sufficient!

Trees and Large Trunk Shrubs – Trees and large trunk shrubs need lots of water.  They have a root system that is very good at finding water.  Roots will travel long distances, if needed, and they are not prejudice.  The moisture und the foundation works just fine.  Some large trees can drink up to 500 gallons of water per day!  Imagine having 10 large trees around your home.  They could drink as much as 5,000 gallons of water per day!  A typical water sprinkler system would have to run 12 hours or more, without runoff, to supply this much water.  It is unlikely that you would be willing to pay a water bill this high each month.  So, in order to control the moisture level under the foundation, the roots of the trees and large shrubs must be controlled.  The following will help guide you to the right balance between landscaping and protecting your foundation:

• A root barrier installed around the perimeter of your foundation will keep the tree and large shrub roots away fro the foundation and will make the task of keeping a consistent moisture level easy.  Details on the design, installation and maintenance of a root barrier can be obtained from a licensed qualified landscaper.
• It is important to keep trees and large trunk shrubs far away fro the foundation or a root barrier should be installed.  As a rule of thumb, any shrub that must be trimmed or cut back more than once per year should not be placed near the foundation.  It the trunk of a mature shrub gets greater than 1 inch in diameter, it should be considered a large trunk shrub.  For example, re-tipped photinias are not recommended because they grow very fast and can get very large.  Crepe myrtle trees and yaupon hollies are also okay as they only require one trimming per year and are low water consuming trees.  However, even with crepe myrtle and yaupon hollies, they should be located 3 feet or more from the foundation.
• All volunteer trees should be removed while they are small to prevent them from becoming large trees.

Consistent Moisture Around the Foundation – With proper drainage and tree roots controlled, it becomes much easier to maintain consistent moisture levels at and under the foundation.  The following watering techniques will help maintain your foundation.  If foundation corrections are needed, refer to a licensed qualified structural engineer.

• The area between the root barrier and the foundation should be kept neither wet nor dry.  The soil should be moist to dry to the touch (not wet to the point of mud or dry to the point of cracking).  Once the tree and large shrub roots are kept away with a barrier, changes in soil moisture levels will be much slower.  Normal lawn watering every few days through the summer should suffice.  During periods of drought or very hot conditions, watering may be required every other day.
• Watering without cutting the roots and installing the barrier does nothing for the foundation.  The trees will simply consume the water faster than you can reasonably put it out.
• Homes without sprinkler systems should use a soaker hose (the black hoses are preferred) around the exterior of the home during dry months.  Hoses should be placed 18 to 24 inches from the foundation and be regulated until they begin sweating.  If an area begins to pond, watering should be halted.  Resume when the soil will absorb water.
• Some areas around the foundation may need more water than others.  Areas to the south and west typically require more watering due to the extended hours of full sun.  Sides of the home with rain guttering likely need more watering than sides without, during times of frequent rainfall.  Since most rain water runs off, do not count on it to water the foundation.

Maintenance of the Root Barrier – The root barrier will be effective in preventing tree roots from removing the moisture near the foundation.  However, there are still some small maintenance requirements, as follows:

• Periodically (every year or as noticed) inspect the area where the root barrier was installed for roots trying to go over the barrier and cut, as needed.