Underpinning is the process of increasing the bearing capacity of a foundation to make it firm against subbase destabilisation by constructing new, deeper footings below the existing footings to prevent further movement of your property. This is done by digging beside and under your house and utilising steel or concrete to create a much stronger footing. These are traditional concrete underpins.
Depending on what the structural engineer deems required to hold the subsidence of the foundation affecting the property, screwpiles may be drilled metres into the ground to find more stable soils.
Each area has different soil characteristics, and Adelaide being home to clay-limestone soils is quite unstable for foundations. In the end, you need a stronger foundation to bear the load. House subsidence, essentially the downward shifting of the ground, may have weakened the foundation. It takes underpinning specialists to repair those cracked walls and underpinning problems.
This process of underpinning a house may involve increasing the length and breadth of a foundation in order to strengthen its weak footing. It helps to stop house subsidence and create a firm ground for resting your foundation. Oftentimes, after a foundation repair is complete, the cracks on the walls may not close completely, making wall repairs necessary.
When underpinning specialists suggest foundation repair through underpinning, in most cases, the soil profile has a downward reflection, which may not adequately support the foundation. In the end, deeper footings are constructed to bear the load of the structure, stopping subsidence and cracks appearing.