When the soils supporting your foundation system are not providing adequate support, underpinning the foundation system may be necessary. Underpinning usually refers to structurally reinforced concrete beams, pilings (pipe piles), columns (caissons) which are placed under your foundation system to provide adequate vertical or lateral support. Underpinning and other types of stabilization methods are used to mitigate fill settlement, expansive soil, and improperly compacted soil under the foundation.
Pipe piles are used to gain vertical support in poor soils. Pilings are driven through the weak soil to reach competent soil for proper support. Piles are often used in areas with limited access for big equipment.
Caissons are steel reinforced columns of concrete placed into pre drilled holes to gain vertical and horizontal support.
Underpinning using a grade beam is intended to support from below and significantly stiffen the weak area.