To install concrete underpinning, the soils must be excavated from around the foundation. Larger concrete footings are poured beneath the exiting footings. Once the concrete has cured, the soil is backfilled. When it comes to foundation footings, “bigger” is not necessarily “better”. Most of the time, the underpinning will not extend beyond the problem soils under your home. If this is true, the larger footings you just paid for will continue to move and cause damage.
Concrete shrinks as it cures, and small gaps can also be formed between the new footing and the old one. Open gaps beneath a home are never a good thing! When concrete underpinning is installed and fails to solve the problem, it is much more expensive to repair. Before installing a new foundation system, all that added concrete will need to be removed.