Underpinning foundation is a method of strengthening the foundation of a building. This can be done by reinforcing the existing foundation, strengthening the soil by introducing an expanding filler or extending the foundation so that the load is distributed over a greater surface area.
When should underpinning be used?
Underpinning is usually required when the original foundation is not stable enough to support the house.
- The foundation may need to be inspected for structural problems if the soil supporting it has changed in some way, such as through subsidence, expansion/contraction due to moisture changes, or large trees nearby.
- The foundation of the building was not designed with the properties of the soil in mind, meaning it is inadequate for conditions.
The foundation of the building was not designed to withstand the soil conditions.
- Following a major renovation, the structure has been used in a different way.
- The construction of a new building nearby has resulted in the excavation and removal of soil that supports the existing foundations.
- To increase the load-bearing capacity of an existing foundation, its dimensions must be increased or its material strengthened.
- Natural disasters such as earthquakes and floods can damage a structure to the extent that it becomes unstable.