FOUNDATION FACTS
On this page we will try to convey a basic understanding of foundations and how they affect the homeowner and the potential buyer.
WHY DO THESE NICE, WELL-BUILT HOMES HAVE FOUNDATION PROBLEMS?
Most people tend to believe that the contractor cut corners and the homeowner is now paying the price. While that may be true in few instances, it is rarely the cause of foundation problems. Problems with the foundation can occur even in the best homes in the best neighborhoods. The problem is not usually with the builder, but with the highly plastic clays that predominate the area. The surface clay, commonly called GUMBO, has high plasticity with a large potential for changes in volume with changes in moisture. It is this change in volume that causes foundation problems. The moisture under the center of the house is trapped by the concrete and thus remains relatively constant, while the moisture at the edges vary from dry in our summer months, to wet in our late winter/early spring months.
DOES WATERING MY FOUNDATION HELP PREVENT FOUNDATION PROBLEMS?
This has been a hot topic in our area for a number of years. The proper response is this: "Yes, if you do it correctly." The critical place to hold a constant moisture content is at the bottom of the grade beam, which is the thickened edge of the concrete slab. With no watering, the seasonal variation in moisture causes the clay to shrink in the dry months and expand in the wet months. In dry weather, the clay shrinks and the edge of the slab moves down. In wet weather, the slab moves back, but not all the way back. In subsequent drying, the slab goes down even further. This movement is the cause of most foundation problems.
The key to preventative maintenance is to keep the moisture under the grade beam relatively constant. Several methods have been tried with varying negative results. First, homeowners would simply water with a water hose. This had little beneficial and sometimes negative results. They would water too much, and then not water enough. This "sometime watering" led to more variation than naturally occurred. Second, a soaker hose was hooked to a timer. This was a more consistent way of watering: however, over 80% of the water was wasted in either runoff or evaporation.
Researchers a the University of Texas did exhaustive studies and reached the conclusion that the best available preventative measure is a constant moisture level in the soil maintained by a porous hose buried six to eight inches under the ground around the perimeter of the foundation. These systems are not a cure-all, nor will they correct existing foundation problems. They are, however, the best preventative maintenance solution and are highly recommended.
WHY MY HOUSE AND NOT THE NEXT DOOR NEIGHBORS?
This anguishing call is heard far too often. Is it the luck of the draw? No, there are valid reasons, and they are many and overlapping. The design of the house, the site preparation, weather conditions during the site preparation, moisture content of the sub-soil, moisture content in the cement and the placement technique of the cement all enter into it. Houses of today tend to be more complex than the simple square box of yesterday. These beautiful bedroom wings and breakfast areas protruding from the house make today's home very interesting. They also tend to act independently and thus cause foundation problems. The preparation of the site by the contractor varies from lot to lot. Did he have to remove a tree where the slab was poured? Did he put in fill dirt on your site? Was the slab poured after very dry or very wet conditions? Was there rain during the curing period of the concrete?
This being said, every house responds to the soil differently. Some houses may have significant building cracks, while others have sheet rock cracks, and others have just a deflection in the floor. If your house is having symptoms such as these, please get an inspection by a qualified foundation engineer.
