Underpinning

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

The original foundation is not strong or stable enough.
The usage of the building has changed.
The type of soil supporting the foundation may have changed (possibly through subsidence) or were misjudged during planning.
The construction of nearby structures causes the excavation of soil supporting existing foundations.
It is more economical, due to land price or otherwise, to work on the current structure's foundation than to build a new one.

Category:Construction