Underpinning is needed where a building or structure is not secure or stable. Injected grout blocks are installed below the footings to stabilise the bearing capacity of the soil underpinning the building. Sinking is often caused by soil not being compacted enough prior to construction. Underpinning ensures that no further damage is caused to the 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.
- The properties of the soil supporting the foundation may have changed (possibly through subsidence) or were mischaracterized during design.
- The construction of nearby structures necessitates the excavation of soil supporting existing foundations.
- To increase the depth or load capacity of existing foundations to support the addition of another storey to the building (above or below grade).
- It is more economical, due to land price or otherwise, to work on the present structure’s foundation than to build a new one.
- Earthquake, flood, drought or other natural causes have caused the structure to move, requiring stabilisation of foundation soils and/or footings.
- Water damage to a structures like soak wells, down pipes, broken pipes, old and neglected gutters, and generally poor maintenance buildings and structures.