Underpinning means to “Pin Under”. Pins of concrete or steel are placed under walls or footing to provide these elements additional support. Usually an “Underpinner” is called in after the existing foundations have failed or are about to fail, Some times the “Underpinner” is called to beef up existing footing load bearing capacity as new renovations above are going to add additional loads.
This type of work has significant risk involved hence the need for experienced professionals.
Usually starts with excavation to find the bottom of existing footings and then determine how deep we need to go to accommodate the needs we have. The soil profile will determine the way we go about the underpinning works as the methodology is quite different for sand, clay or below water table. We may need to shore up the soil, carry footings to rock or dig down to new levels for a basement.
Typical sectional concrete underpin of walls to extend walls down.