Underpinning

In construction, underpinning is the process of strengthening and stabilizing the foundation of an existing building or other structure. Underpinning may be necessary for a variety of reasons:

• The original foundation is simply not strong or stable enough, e.g. due to decay of wooden piles under the foundation.
• The usage of the structure has changed.
• The properties of the soil supporting the foundation may have changed or was mischaracterized during planning.
• The construction of nearby structures necessitates the excavation of soil supporting existing foundations.