underpinningunderpinning is the process of strengthening the foundation of an existing building or other structure. Underpinning may be necessary for a variety of reasons: The original foundation isn't strong or stable enough. The usage of the structure has changed. More is the process of strengthening the foundationThe structural base that transfers the building’s load to the ground. More of an existing building or other structure. Underpinningunderpinning is the process of strengthening the foundation of an existing building or other structure. Underpinning may be necessary for a variety of reasons: The original foundation isn't strong or stable enough. The usage of the structure has changed. More may be necessary for a variety of reasons: The original foundationThe structural base that transfers the building’s load to the ground. More isn’t strong or stable enough. The usage of the structure has changed.