Water sticks to almost anything including clay. This attraction causes clay soil to swell. The trick is to use a non-swelling chemical to stick to the clay before water does. When an appropriate concentration of the right chemicals is injected into clay, the chemicals stick to the clay molecules and prevent the clays from absorbing water. Once in place, the chemicals stay attached to the clays. In a way by injecting the chemicals into the soil and “coating” the clay, you create a moisture barrier, stopping water from causing more foundation upheaval.
In most cases, for existing structures, chemical injection is done around the perimeter of a foundation. If there are driveways, patios, decks, or other paved surfaces, ¾ inch diameter holes are drilled through the paving to reach the underlying soils. The chemical solution is injected to depths ranging from 7 to 10 feet. The solution is injected at relatively low pressures, typically on two separate days. The solution is pumped from a truck to a manually operated injection wand.
Injections can be done on the interiors of buildings; however, interior treatment requires that holes be drilled though the floor every 2 feet (one hole for every 4 square feet). While exterior injections are hardly noticeable, this is not true for interior injections. When interior injections are being done, the contents of a home must be removed because the chemicals do stain and can splatter during injection.
The materials used in the solution are not toxic in small quantities. In the ground, in dilute concentrations, they actually act as fertilizers. The materials should not be ingested. If the solution gets on a person’s skin, simply wash it off with soap and water.
Foundation maintenance can prevent some types of upheaval through the installation of proper foundation drainage including:
If foundation upheaval has already occurred, the following types of foundation repairs are recommended: