When the soil your home is built on can no longer support the weight of your home, the structure will start to settle. An expert may recommend installing a deep foundation system to stabilize your home.
Deep foundation soils and deep foundation systems are best understood by starting with the ground. Soil is made up of obvious layers which have different qualities and are a good indicator of how deep you need to extend your foundation.
The top layers of soil compress and easily compact – this is where settlement occurs and where you’ll find problem soils like expansive clay. The deeper soil layers, like parent rock, are stable and less likely to move. This is why a deep foundation pier system is installed into competent load bearing soils or bedrock.
The top layer of soil consists of decomposed organic matter. This isn’t to be confused with the layer of leaves and decomposing materials on top of the ground. Over time these things will break down and become the layer of organic matter.
This is also called topsoil or humus. It consists of dark, decomposed organic materials (i.e. leaves, grass, branches, etc…) The surface soil is were you’ll find earthworms, potworms and forms of fungus and bacteria that are dependent upon plant roots.
This is the layer of soil where you’ll commonly find clay, expansive or consolidating soils. When your home experiences settlement problems, it’s typically due to this layer of soil. Settlement could be caused by the problem soils mentioned above or poor site preparation and construction.
This section of soil is also known as bedrock. It can contain large rocks and other larger, solid materials. It’s much deeper than the other layers and isn’t typically affected by weather or moisture changes. Bedrock is much deeper than the other soil levels, beyond the depth that roots can grow, and as a result, doesn’t have the shrinkage and settlement problems that can occur in other soil layers. Most deep foundation solutions are installed to the stable parent rock.